01 scope june2014.qxt scope cover

SCOPEINSTITUTE OF PHYSICS AND ENGINEERING IN MEDICINE | www.ipem.ac.uk | Volume 23 Issue 2 | JUNE 2014

10 things you can do on

the new IPEM website

Tomotherapy QA survey

IPEM’s Research and

Innovation Awards

Repair to CareHelping in South SudanP08 FAILURE MODE ANALYSISApplication of failure mode andeffects analysis in radiotherapy

P22 CT GENTLY APPMobile tool for personalised low-dose CT and CBCT scans

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CONTENTS

SCOPE | JUNE 2014 | 03

THIS ISSUE

33 Association for the Advancement of Assistive TechnologyHannah Dalton

35 International Society for Clinical ElectrophysiologyRuth Hamilton

37 IEEE Medical Imaging ConferenceJose M. Anton-Rodriguez

40 SPIE Photonics West 2014Megan Duffy

50 Discoveries at the dawn of the electronic eraThe second part of this historical series, showing howresearch into the nature of electricity led to improvedmeasurement techniques

04 President’s letter Celebrating achievements

05 CEO’s column Providing opportunities

06 Editor’s comment Saying farewell

07 News Promising results from recent research

31 Technologist news A new development in this subject area

44 Book reviews Many interesting new books and reports

REGULARS

HISTORICAL FEATURE

MEETING REPORTS

FEATURES

12

50

35

40

12 Cover feature: Repair to CareA Tropical Health Education Trust medical equipmentpartnership with a hospital in South Sudan

15 10 things you can do on the website – www.ipem.ac.ukThere are new features and content, so visit the site todayand you might be surprised to see what you can do online

16 Tomotherapy quality assurance survey in the UKA survey of current Tomotherapy QA practice in order tocreate a framework for appropriate recommendations

22 A mobile tool for personalised CT and CBCT scansDeveloping and launching a new iPhone app to give apersonalised estimation of the radiation dose received

26 IPEM’s Research and Innovation AwardsRecent IPEM awards helped to fund six research projectswith innovative developments and significant results

28 IPEM accreditation framework for MSc coursesDesigning a new framework to offer a wider vision for thewhole medical physics and bioengineering community

PRESIDENT’S LETTER

he new generation of trainee clinical scientistsundertaking the Scientist Training Programme(STP) are subject to an assessment regime verydifferent from the one most of us are used to.As well as completing workplace-based

assessments with unfamiliar acronyms such as DOPS,OCEs and CBDs, at the end of their training period STPtrainees come together to undertake Objective StructuredFinal Assessments (OSFAs). OSFAs consist of a series of‘stations’ involving ‘practical tasks, clinical scenarios,scientific and patient interactions’ (I quote from theNational School’s trainee handbook). They are farremoved from the portfolio-based interviews thatcharacterise the IPEM scheme, and closely resemble theObjective Structured Clinical Examinations (OSCEs) that Iwas familiar with in my former role as a member of a

medical school board of examiners. In some of ourdisciplines, designing clinically focussed assessments ischallenging, but I believe this new emphasis is correct.Even for those clinical scientists with little direct patientinteraction, patient experience should surely be at theheart of all that we do. As I write, the experience of themock OSFAs held in April is being digested by traineesand assessors alike, in preparation for real OSFAs in Julyand August. As I have mentioned before in these pages,despite the fact that IPEM is no longer responsible forclinical scientist training, our members remain heavilyinvolved in its delivery and assessment. Under aMemorandum of Understanding with the National Schoolfor Healthcare Science, IPEM is responsible for provisionof assessors to develop and run the OSFA stations. I amgrateful to the many members who have put themselvesforward for this new and challenging task, some withprevious experience of assessment and some new to therole, ensuring that professional input to traineeassessment is as strong as ever. I also wish all of our STPtrainees the very best of luck as they prepare for theirOSFAs, which will provide them with the opportunity todemonstrate what they have learned over the past 3 yearsin terms of both science and its clinical application.

Work on Higher Specialist Scientific Training (HSST)has also progressed, led by the medical royal colleges

with IPEM specialist input. Clinical biomedicalengineering and medical physics curricula are nowavailable on the NHS Networks website athttp://www.networks.nhs.uk/nhs-networks/msc-framework-curricula/hsst-higher-specialist-scientist-training. Both curricula emphasise the role of consultantclinical scientists in innovation, not just leading existingservices (important though that is), but also providingstrategic leadership and championing evidence-basedadoption of new techniques with potential to improvepatient outcomes. The first HSST entrants will start theirtraining programmes in September, although the timetableand funding remain key concerns.

IPEM is also exploring other opportunities to engagewith training of the healthcare science workforce. In April,the Board of Trustees agreed to establish a newApprenticeship Panel to explore how we might supportthis important new area of training. The following day,entirely coincidentally, Jo Young, the chair of the newpanel, received an Advancing Healthcare Award as part ofthe team that established apprenticeship training at King’sCollege Hospital. Clearly this part of our training agendais also in safe hands!

At the same ceremony, the IPEM Award for Patients asPartners in Science was presented for the first time. Theaim of this new award is once again to sharpen the focusof healthcare science professionals on patient experience.The winning team, Trainee Clinical Scientist JulieWooldridge working with nursing and medicalillustration colleagues, had developed a picture book tomake electrodiagnostic tests less daunting for children. Itis a great example of how clinical scientists can maketechnology more accessible to patients, with the additionalbenefit of improving patient compliance with complexand demanding tests. There was also an award, sponsoredby the Academy for Healthcare Science, for TraineeRadiotherapy Physicist Louisa Adler, who worked withradiographer colleagues to use the virtual environmentradiotherapy training system (VERT, itself developed byIPEM member Professor Andy Beavis) to demystify thetreatment process for patients and their relatives.

It must be awards season, because the previous week atthe annual Healthcare Science Awards ceremony TraineeClinical Engineer Megan Duffy received the Rising Star(Medical Physics and Clinical Engineering) award, whileIPEM member and volunteer Nick Dudley was runner-upfor the Healthcare Scientist of the Year award itself.

My congratulations to all of these well-deservingwinners. The number of trainees receiving awards wasnotable. Together with the increased focus on benefit topatients, this bodes very well for the future.

Celebrating achievements

TSTEPHENKEEVILPresident

Stephen Keevil explains what new trainees must achieve and

congratulates award-winning healthcare work and workers

I am grateful to the many members who haveput themselves forward

for this new task““

04 | JUNE 2014 | SCOPE

CEO’S COLUMN

his is the time of year at whichyou might find yourselfvoting in a ballot to decidewho should be elected tosome of IPEM’s

committees. Or you might not – ithas been rare to have too manyvolunteers for any of theseopportunities!

What members do, orwant to do, for IPEM was atheme in the recentmember survey, in whichonly 25 per cent ofrespondents said theydid anything for IPEM –and only 23 per cent saidthey would in future.

Behind theseheadlines, however, lies adifferent story. Many ofthe comments postedalongside the replies were reallyhelpful in clarifying why people don’t – orcan’t – take up opportunities that would be goodfor their CPD or CV; that would bring benefits innetworking and making connections; or just provide thesatisfaction of doing something more than the day job.

Unsurprisingly, lack of time was a key issue formany. These people may find opportunities other thancommittee membership to be more helpful. There arethings people can do that are quick, or can be fitted into small chunks of time, such as identifying a newsstory, commenting on an image or proofreading adocument. These activities might also suit the peoplewho said that their employer would not supportprofessional activity. Similarly for the problem of thecost of getting involved: many things can be donewithout travelling or incurring other expenses. Whereexpenses do accrue, IPEM will reimburse them, inaccordance with our expenses policy.

Some respondents commented on the difficult

process of applying for an IPEM volunteeropportunity. In this year’s round of

advertising for committee places, we haveput all the role descriptions online, and

asked only for an email and half-pagecareer résumé, to simplify this

process. For other activities, wedon’t even need this – and we

don’t need CRB checks, as somequeried, as no volunteers onIPEM business are going towork directly with vulnerablepeople.

Many people citedreasons why they couldn’tcome to meetings or get toYork, including beingabroad, having childcare orother family commitments,

or being unwell. For some,the fact that many IPEM

meetings take place in Londonor other cities apart from York may

help. The teleconferencing and new web meetingfacilities also enable people to hold meetings from

home; and we are planning to install video-conferencing in our meeting rooms to reduce traveldemands. Everyone who wants to should be able to getinvolved.

Even if practical problems are overcome, however,there are people who simply didn’t know that IPEMwants their help, or what opportunities exist. To tacklethis, we are keeping a running list of volunteer activitieson the Members’ page of the website, and emailingthose who told us they wanted to get involved regularly.To be added to this list, just email [email protected].

Finally, two issues that are opposite sides of the samecoin: the belief that IPEM is a ‘closed shop’ for the few;and the people who say they don’t have anythingrelevant to contribute. Everyone can engage with theirprofessional body, from the least experienced or newest,who bring fresh ideas and energy, to the longest-serving,who have a vast toolkit of experience and knowledge todeploy. However, if people believe the same membersdo everything at IPEM and don’t attempt to getengaged, this will become the traditional self-fulfillingprophecy!

On the other hand, if we get better at offeringvaluable opportunities to members, and every memberdecides to do something – maybe next year you will beasked to vote in dozens of ballots.

Providing opportunities

TROSEMARYCOOK CBEChief ExecutiveOfficer

Rosemary Cook CBE proves that there are many ways in which members can

volunteer within IPEM, despite there being obstacles which can be overcome

There are people whosimply didn’t know that

IPEM wants their help, orwhat opportunities exist“

“


‘ GETINVOLVEDIPEM wantsyour help!

We are keeping arunning list ofvolunteeractivities on theMembers’ pageof the website,and emailingthose who toldus they wantedto get involvedregularly. To beadded to thislist, just [email protected]

would like to take this opportunity to bid a fond farewell to allyou loyal readers. After 7 years on the Scope editorial team, thelast 2 as Editor-in-Chief, I will now be moving on to follow otherpursuits. Usman Lula, who is the multi-talented Assistant Editor,as well as News Editor and Book Reviews Editor, will be stepping

into my shoes. I’m sure he will steer the good ship Scope along asteady path. It has been a real pleasure being involved with Scope;the editorial team, the publication team and all the volunteerauthors have made my role easy. I wish good luck to Usman.

My departure creates a vacancy; we are looking for a newAssistant Editor for Scope and possibly have some other vacant poststoo, such as Meeting Reports Editor which will become availablewith the departure of our long-standing editorial board memberAngela later this year. Thank you, Angela, for all your hard work.Volunteering for IPEM in any capacity can be very rewarding and Ihave particularly enjoyed my time with Scope. If you look at theIPEM website (http://www.ipem.ac.uk/Members/GetInvolved-InternalExternalvacancies.aspx), many volunteering jobs are listed.Please do get in touch if you are interested or want a bit moreinformation.

This issue, despite being my last, is as chock-full as ever. We haveanother instalment from the THET initiative where they report onthe link between South Sudan and Hampshire Hospitals NHSFoundation Trust.

Moneywise, times are still tight, not least for those of us doingresearch. David Brettle and Elspeth Bartlet report on IPEM’sResearch and Innovation Awards. The Awards provide short-termresearch projects with up to £10,000 for equipment or services.Recipients of this award in 2012 report back on their successfulprojects on page 26.

On page 28 we report on the new IPEM accreditation frameworkfor Masters level courses. The authors describe the need for a newframework resulting from the recent changes to the training ofhealthcare scientists and engineers in England and Wales, plus theactivities of a working group investigating the effects chaired byProfessor Dick Lerski.

Our usual mix of news, book reviews, travel reports andtechnologist reports are also joined by the fascinating secondinstalment of Stanley Salmons’ history of thedevelopment of biomedical engineering onpage 50.

So for now, good bye.

I


EDITOR’S COMMENTScope is the quarterlymagazine of the Institute of Physics and Engineeringin MedicineIPEM Fairmount House, 230 Tadcaster Road, York, YO24 1EST 01904 610821F 01904 612279E [email protected] www.ipem.ac.ukW www.scopeonline.co.uk

EDITOR-IN-CHIEFGemma WhitelawRadiotherapy Physics,Basement, New KGVBuilding, St Bartholomew'sHospital, West Smithfield,London, EC1A 7BEE [email protected]

ASSISTANT EDITORUsman I. LulaPrincipal Clinical Scientist,1st Floor, Radiotherapy,Building, Medical Physics -University, HospitalsBirmingham NHSFoundation Trust, QueenElizabeth Hospital, QueenElizabeth Medical Centre,Birmingham, UK B15 2THT 0121 371 5056E [email protected]

MEETING REPORTS EDITORAngela CottonHead of Non-IonisingRadiation Support, MedicalPhysics & Bioengineering,Southampton GeneralHospital, Southampton,SO16 3DRT 023 8120 8616E [email protected]

NEWS EDITORSUsman I. LulaPrincipal Clinical Scientist,1st Floor, RadiotherapyBuilding,Medical Physics,Queen Elizabeth Hospital,Queen Elizabeth MedicalCentre, University HospitalsBirmingham NHSFoundation Trust,Birmingham, UK B15 2THT 0121 371 5056E [email protected]

and

Richard A. AmosOperational Lead for ProtonBeam Therapy Physics,Radiotherapy PhysicsDepartment, UniversityCollege London HospitalsNHS Foundation Trust,1st Floor East – 250 EustonRoad,London NW1 2PGT 0203 447 2369E [email protected]

BOOK REVIEW EDITORUsman I. LulaPrincipal Clinical Scientist,1st Floor, Radiotherapy,Building, Medical Physics -University, HospitalsBirmingham NHSFoundation Trust, QueenElizabeth Hospital, QueenElizabeth Medical Centre,Birmingham, UK B15 2THT 0121 371 5056E [email protected]

ACADEMIC EDITORProfessor Malcolm SperrinDirector of Medical PhysicsRoyal Berkshire NHS,Foundation Trust, LondonRoad, Reading, RG1 5ANE Malcolm.Sperrin@royal

berkshire.nhs.uk

INTERNATIONAL EDITOR(Developing countries)Andrew GammieClinical Engineer, Bristol Urological Institute,BS10 5NBT +44(0)117 950 5050

extension 2448 or 5184E [email protected]

INTERNATIONAL EDITOR(North America)Richard A. AmosOperational Lead for ProtonBeam Therapy Physics,Radiotherapy PhysicsDepartment, UniversityCollege London HospitalsNHS Foundation Trust,1st Floor East – 250 EustonRoad,London NW1 2PGT 0203 447 2369E [email protected]

JOINT CLINICALTECHNOLOGIST EDITORSFrances RyeSenior Clinical Technologist,Department of RadiotherapyPhysics, Poole HospitalNHS, Foundation Trust,Longfleet Road, Poole,Dorset, BH15 2JBT 01202 442307E [email protected]

Trevor Williams and DaveStangeSenior ClinicalTechnologists,1st Floor,Radiotherapy Building, Medical Physics, QueenElizabeth Hospital, QueenElizabeth Medical Centre,University HospitalsBirmingham NHSFoundation Trust,Birmingham, UK B15 2THT 0121 371 5051E [email protected] [email protected]

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Scope is published quarterlyby the Institute of Physicsand Engineering in Medicinebut the views expressed arenot necessarily the officialviews of the Institute.Authors instructions andcopyright agreement can befound on the IPEM website.Articles should be sent tothe appropriate member ofthe editorial team. Bysubmitting to Scope, youagree to transfer copyrightto IPEM. We reserve theright to edit your article.Proofs are not sent tocontributors. The integrity ofadvertising material cannotbe guaranteed.

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ISSN 0964-9565

Saying farewell

GEMMA WHITELAW EDITOR-IN-CHIEF


NEWS BY USMAN I. LULA AND RICHARD AMOS

The physical characteristics of

proton beams offer the potential

for increased sparing of healthy

tissue during radiotherapy than

those of conventional photon

beams. However, optimal use of

these characteristics during

proton beam treatment planning is

often limited by significant

uncertainties in the stopping power

estimates used to calculate proton

range. The stopping powers are

derived from the Hounsfield units

in x-ray CT scans of the patient and

their uncertainty arises from a lack

of one-to-one mapping between

the two parameters.

A team of researchers at

Aarhus University in Denmark

have demonstrated improved

accuracy of stopping power

estimates with a dual-modality

image reconstruction (DMR)

technique that combines x-ray

cone-beam CT (CBCT) data with a

proton CT scan. DMR corrects the

x-ray-based CBCT stopping power

estimates using the proton data by

identifying regions in each scan

that have similar stopping powers

on the basis of a statistical weight

that quantifies the confidence in

the CBCT stopping power

estimates.

The group tested DMR using

Monte Carlo code to simulate 230

MeV proton CT scans on a digital

version of a cylindrical phantom.

The simulated scans detected

entry and exit positions, and the

momentum of every proton,

collecting data over 360˚ around

the phantom using two opposing

detectors. A physical x-ray CBCT

scan of the same 15-cm-diameter

phantom was acquired using an

onboard kilovoltage (kV) imager on

a conventional linac.

The group simulated proton CT

scans using both full 360˚ data

acquisition and incomplete

sampling, assessing the benefit of

DMR where proton range is less

than the thickness of the patient in

a given direction. This scenario

will likely arise in treatment sites

other than the head, given that a

230 MeV proton beam – the

highest energy typically produced

by commercially available proton

therapy systems – has an

approximate range of 33 g/cm2.

With 360˚ sampling, proton CT

and DMR consistently provided

markedly more accurate stopping

power estimates than x-ray CBCT,

with a mean RMS error of 0.003

across a range of phantom insert

materials. In one example, the

RMS error for a polystyrene insert,

which has a reference stopping

power value of 1.03, was

approximately 11 times smaller for

DMR and proton CT compared with

CBCT.

Reduced angular sampling of

the proton CT data did have

reduced accuracy compared to

360˚ sampling; however, the

technique was still more accurate

than CBCT in isolation. For the

same polystyrene insert, DMR was

between 1.5 and 3.5 times more

accurate than CBCT.

An advantage of the DMR

approach is that proton CT and

CBCT scans can potentially be

obtained simultaneously with a

proton gantry system with onboard

kV imaging. This avoids geometric

errors associated with scanning at

different times. The team are

currently in talks with groups at

Loma Linda University in California

and Ludwig-Maximillians

University in Munich to arrange

testing of DMR on prototype proton

CT scanners that these groups are

developing.

Proton CT improves stopping power accuracy

PROTON BEAM THERAPY

‘ NEWS EDITOR’S COMMENT:Range uncertainty has long

been regarded as the Achilles

heal of proton beam therapy.

Physical range can be

significantly impacted by

patient set-up errors, patient

motion, weight loss or gain,

internal anatomical changes

and/or motion. Additional to

this, the uncertainty in stopping

power estimates based on x-

ray CT data make even the

calculation of range inaccurate.

A number of innovations to

address these uncertainties in

proton range are being

investigated by many groups.

The full potential advantage of

proton beam therapy won’t be

realised until range uncertainty

is minimised.

For information regarding

uncertainties in proton beam

therapy, e-mail me at

[email protected]

Dual modality reconstruction: DMR (left) and proton CT (right)

‘ MORE INFORMATIONThis paper was published in

Med Phys 2014; 41: 031904.

http://dx.doi.org/10.1118/1.48

64239



Stereotactic radiation surgery

(SRS) is a complex process

involving several professional

groups whose aim is to

precisely deliver a single

fraction of high-dose radiation

to the target volume whilst

sparing the surrounding

healthy tissue. The number of

steps leading up to the

preparation and delivery of

treatment is critical and may

lead to errors. Implementation

of a comprehensive quality

assurance (QA) programme can

detect and correct errors, thus

improving the safety and quality

of treatment delivery.

In radiotherapy processes, a

number of methods can be

applied to analyse and prevent

adverse events (AEs) and near-

misses and to establish

preventative measures. A

proactive approach aims to

study the whole process, or

part of it, and identify the

criticalities that could never be

detected if an AE had not

occurred. The most frequently

applied proactive method to

analyse radiotherapy processes

is the FMEA. This method

consists of the examination of

potential failures of the

process, their consequences on

the system, the existing

preventative measures for

limiting the occurrence of the

mode and the existing

corrective measures for

limiting the consequences.

The aim of this study was to

analyse the application of the

FMEA to intracranial SRS by

linear accelerator in order to

identify the potential failure

modes in the process tree and

adopt appropriate safety

measures to prevent adverse

events and near-misses, thus

improving the process quality.

A working group was set up

to perform FMEA for

intracranial SRS in the

framework of a QA programme.

The working group met weekly

for 3 months to define the

process tasks and steps and to

discuss the results. FMEA was

performed in four consecutive

tasks: (1) creation of a visual

map of the process; (2)

identification of possible failure

modes; (3) assignment of a risk

probability number (RPN) to

each failure mode based on

tabulated scores of severity,

frequency of occurrence and

detectability, and (4)

identification of preventive

measures to minimise the risk

of occurrence. Refer to table 1

for the 10-point scale used to

score each of the categories.

The whole SRS process was

subdivided into 73 single steps;

116 total possible failure modes

were identified and a score of

severity, occurrence and

detectability was assigned to

each. There were two failure

modes with RPNs greater than

125 related to the risk of high-

dose deposition to health tissue

due to the wrong collimator and

an error in the isocentre

localisation. Another two

failure modes with high RPN

values were due to incorrect

contouring of the target volume

and to the incorrectness of the

patient’s documentation. Refer

to table 2.

FMEA is a simple and

practical proactive tool for

systematic analysis of risks in

radiotherapy. FMEA led to the

adoption of major changes in

various steps of the SRS

procedure. The working group

recommended that FMEA

should be performed in all

high-precision high-dose

techniques to prevent AEs that

could result in severe harm to

patients. The group also stated

that apart from the

implementation of FMEA, more

general issues should also be

considered, for example the

selection and training of staff.

MEDICAL PHYSICS‘ MORE INFORMATIONThe work was published by:

Masini L, Donis L, Loi G,

Mones E, Molina E, Bolchini C,

Krengli M. Applications of

failure mode and effects

analysis to intracranial

stereotactic radiation surgery

by linear accelerator. PractRadiat Oncol 2014. doi:

10.1016/j.prro.2014.01.006

‘ NEWS EDITOR’S COMMENT: FMEA has been utilised within

healthcare since the early

1990s. It is a useful tool to aid

multidisciplinary groups in

mapping and understanding a

process of care. This study

shows that in employing the

FMEA, different sources of

information has been used

(‘working group’) to identify

potential failures and not

simply the experience and

knowledge of any one

individual. The authors also

highlight that more general

issues should be considered

in addition to using the FMEA

which has also been

supported by Shebl et al.(BMC Health ServicesResearch 2012; 12: 150,

http://www.biomedcentral.

com/1472-6963/12/150).

Shebl et al. highlight that

healthcare organisations

should not solely depend on

their FMEA results to

prioritise patient safety

issues. Moreover, Ford et al.recently concluded that

streamlining FMEA provides a

means of accomplishing a

relatively large-scale analysis

with modest effort (Med Phys2014; 41(6)).

In contrast to an FMEA, a

fault tree analysis (FTA) takes

an undesirable event and

works backwards to identify

potential failure modes. This

has the advantage of allowing

the process to be evaluated,

as opposed to looking at the

failure in isolation. The

hazards identified in an FMEA

can be used within an FTA

(Taktak A, Ganney P, Long D,

White P. Clinical Engineering.

Oxford: Academic Press,

2014).

Dr Gareth Webster

highlights that as

radiotherapy treatment

complexity increases with

developments such as

integrated multimodality

imaging, personalised dose

prescription and treatment

adaptation, the importance of

proactive error detection will

take on greater importance.

Although formal approaches

such as FMEA can require a

substantial investment of

resources, the collaborative

environment that this

requires will ensure both a

more robust approach and

better understanding of the

entire pathway by all staff

involved. Dr Webster is a

Clinical Scientist working in

Radiotherapy Physics at the

Queen Elizabeth, University

Birmingham Hospitals, UK.

He has a research interest in

adaptive radiotherapy.

A very useful best practice

guidance document is the

Manual of Cancer Services:Radiotherapy Measures, v5.0,

National Cancer Peer Review

Programme, Gateway

Number 13696,

www.mycancertreatment.

nhs.uk.

Readers may also find the

following sources

informative: ComprehensiveAudits of RadiotherapyPractices: A Tool for QualityImprovement, IAEA 2007;

Radiotherapy ServiceEvidence Guide,Radiotherapy, National

Cancer Peer Review

Programme 2013; Manual ofCancer Services (online

manual can be accessed

from the CQuINS website at

http://www.cquins.nhs.uk);

Improving Outcomes: AStrategy for Cancer,

Department of Health,

Gateway Number 15106,

January 2011 (accessed via

https://www.gov.uk/).

If you have a comment on

this news article, or would

like to share your

experiences with the medical

physics community, then

please get in touch with me

via email:

[email protected]

Failure Mode and Effects Analysis (FMEA):application in radiotherapy



TABLE 2

Step Failure mode Effect S O D RPN Corrective measure

Preparation of thetreatment room

Choice wrongcollimator

Treatment of smaller or largervolume

9 4 5 180Second check by a physician, a physicist

and a radiation therapist

Localisation with LTLFdevice with patient in

treatment position

Wrong coordinateson LTLF device

Treatment of wrong location 9 3 5 135Exportation isocenter data to the

localisation independent system: Vision RT

Contouring GTV andOARs

Wrong volumeGTV underdosage or OARs

over dosage7 2 5 70 Contours review

Clinical and radiologicdocumentation

assessment

Exchange of clinicaldocumentationand/or images

Wrong prescription 7 3 3 63 Cross-checks physician-nurse

D, detectability; GTV, gross tumour volume; LTLF, laser target localiser frame; O, occurence; OARs, organs at risk; RPN, risk probability number; RT,radiation therapy; S, severity

Table 2: Failure modes with the highest risk probability number (RPN) for which corrective measures were adopted. Table kindly supplied byMarco Krengli, Department of Radiotherapy, University Hospital Maggiore della Carita, Novara, Italy. © Elsevier, Masini L, Donis L, Loi G, MonesE, Molina E, Bolchini C, Krengli M. Applications of failure mode and effects analysis to intracranial stereotactic radiation surgery by linearaccelerator. Pract Radiat Oncol 2014. doi: 10.1016/j.prro.2014.01.006

Table 1: Ten-point scoring scale (modified). Table kindly supplied by Marco Krengli, Department of Radiotherapy, University Hospital Maggioredella Carita, Novara, Italy. © Elsevier, Masini L, Donis L, Loi G, Mones E, Molina E, Bolchini C, Krengli M. Applications of failure mode and effectsanalysis to intracranial stereotactic radiation surgery by linear accelerator. Pract Radiat Oncol 2014. doi: 10.1016/j.prro.2014.01.006

TABLE 1

Score Severity Occurence Detectability

1 No damage Remote Very high:

2 Slight and temporary damage that requires no medical intervention 1/10,000 always detected error

3–4 Slight and temporary damage that requires medical intervention Low High:

1/5,000 almost always detected error

5 Temporary damage of medium severity that requires no hospitalisation Medium Medium:

6 Temporary damage of medium severity that requires hospitalisation 1/200 moderate probability of detection

7–8 Serious and permament injury High Low:

1/100 low probability of detection

9 Near-fatal injury Very high Very low:

1/20 almost never detected error

10 Death Remote:

Never detected error

n FIRST MRI LINACThe clinical realisation of MR-

guided radiotherapy could

represent the ultimate

breakthrough in real-time image

guidance – offering soft tissue-

based imaging throughout beam

delivery. The development of the

high-field MRI-guided linac is

being led by the MR Linac

Research Consortium, set up by

Elekta, Philips and University

Medical Centre Utrecht

(http://medicalphysicsweb.org/

cws/article/research/56853).

n IMAGES INSIDE A HEARTA catheter-based device that

provides forward-looking, real-

time 3D imaging from inside the

heart, coronary arteries and

peripheral blood vessels could

guide heart surgeons and

potentially reduce the amount of

surgery needed to clear blocked

arteries (IEEE T Ultrason Ferr

2014; 61: 239).

n VISUALISING HOT SPOTSA team at the Norris Cotton

Cancer Center (New Hampshire,

USA) has for the first time used

Cerenkov imaging to visualise

the treatment beam in a female

breast cancer patient

undergoing radiation therapy.

The images revealed a hot spot in

her underarm, which physicians

and physicists could work to

prevent in future treatment

sessions.

n HANDHELD DEVICEA handheld ophthalmic

screening instrument that scans

a patient’s entire retina in

seconds has been developed by

researchers at Massachusetts

Institute of Technology. Tests

demonstrate that the device

could acquire images

comparable in quality to those

from conventional table-top

optical coherence tomography

instruments used by

ophthalmologists (Biomed Opt

Express 2014; 5: 293).

The management of many life-

threatening illnesses such as

hypoxaemia, ischemia, sepsis

and shock could be possible by

way of monitoring the blood

oxygen level. Devices used for

this purpose include the CO-

oximeter, pulse oximeter and

near infrared spectroscopy.

Pulse oximetry is currently the

standard technique for

measuring arterial oxygen

saturation (SpO2) with

applications in anaesthesia and

critical care.

Arterial oxygen saturation can

be measured by shining light into

the vascular tissue at two

different wavelengths and

measuring the changes in light

absorbance produced during

arterial pulsations. The changes

in light absorbance detected

during these arterial pulsations

are electronically amplified and

recorded as a voltage signal

called photoplethysmographs

(PPGs). The ratio of the

amplitudes of these AC PPG

signals and their corresponding

DC values are then used to

estimate SpO2. Thus, accurate

estimation of SpO2 using pulse

oximeters depends on the quality

of the PPG signals detected.

However, SpO2 measurements

made from extremities become

susceptible to inaccuracies when

peripheral perfusion is

compromised (e.g. during

surgery monitoring triggered by

clinical conditions such as

hypothermia, hypovolaemia and

vasoconstriction).

The aim of this study was to

investigate the suitability of the

human auditory canal as a

central site for reliable

monitoring of PPGs and the

estimation of SpO2.

A dual wavelength

optoelectronic probe along with a

processing system was

developed to investigate the

suitability of measuring PPG

signals and SpO2 in the human

ear canal (EC), see figure 1. A

pilot study was undertaken on 15

healthy volunteers and

comparisons were performed

against PPG signals acquired

from left index finger (LIF) and

right index finger (RIF) in

conditions of induced

vasoconstriction (cold pressor

test). This was to validate the

feasibility of measuring PPGs

and SpO2 from the ear canal. A

minimum drop in SpO2 value of 4

per cent in any given volunteer

was considered to be clinically

significant or as an indicator of

pulse oximeter failure.

The baseline SpO2 results

from the EC pulse oximeter were

in good agreement with both the

finger pulse oximeters. In the

cold pressor test, the amplitude

of the PPG signals acquired from

RIF (cold finger) and the LIF

(warm finger) reduced

significantly, whilst the amplitude

of the EC PPGs stayed relatively

constant (see figure 2).

The RIF and LIF pulse

oximeters failed to estimate

accurate SpO2 in seven and four

volunteers, respectively, whilst the

EC pulse oximeter has only failed

in one volunteer. The failure of the

finger pulse oximeters was purely

due to a reduction in amplitude

and the quality of the PPG signals,

resulting from vasoconstriction of

peripheral blood vessels.

A new and potentially clinically

useful non-invasive EC pulse

oximeter system has been

successfully developed and pilot

tested but will undergo further

clinical testing to ensure that it

meets relevant regulatory

standards. The system promises

reliable monitoring of PPG and

SpO2 in conditions of

compromised peripheral

perfusion.

PHYSIOLOGICAL MEASUREMENT

Monitoring photoplethysmographsand arterial oxygen saturation

‘ MORE INFORMATIONThe work was published by:

Budidha K, Kyriacou PA. The

human ear canal: investigation

of its suitability for monitoring

photoplethysmographs and

arterial oxygen saturation.

Physiol Meas 2014; 35: 111–28.

doi:10.1088/0967-334/35/2/111



‘ NEWS EDITOR’S COMMENT: This is an interesting paper

discussing a device with a

potential for measuring oxygen

saturation levels using PPG in a

novel location of the ear canal.

The results confirm that the ear

canal is much less sensitive to

the effects of peripheral

vasoconstriction than

traditional sites for PPG

measurement and that the

electro-optics to measure PPG

can be relatively easily

incorporated in a simple in-ear

sensor giving a reasonably

consistent output signal. The

ear canal has been used for

some time for measuring body

temperature. The robustness of

the PPG signal in this location

is no great surprise given that

the ear canal has long been

recognised as an environment

maintained at a stable

temperature close to the core

temperature of the body. The

results also suggest that

comparison of finger and ear

canal PPG signals may be a

useful tool in assessing the

status of the sympathetic

nervous system and its control

of blood circulation. Comments

were provided by Dr Steve

Perring who is a Clinical

Scientist in Physiological

Measurement at Poole Hospital

NHS Foundation Trust, UK.

Steve has a research interest in

GI physiology and autonomic

function testing.

Private communications

were with Dr John Allen. John

is Lead Clinical Scientist in

Microvascular Diagnostics at

the Regional Medical Physics

Department, Freeman Hospital,

Newcastle upon Tyne, UK. He is

also an Honorary Clinical

Senior Lecturer at the Institute

of Cellular Medicine (Newcastle

University). His PhD thesis was

based on PPG measurements

and their analysis.

For those interested in

further information on pulse

oximeters, you may want to

read the Buyers’ Guide(CEP10065), Market Review(CEP10066) or Evidence Review(CEP10064). Visit and search on

the following website:

http://nhscep.useconnect.co.

uk/cepproducts/catalogue.

aspx.

If you have a comment on this

news article, or would like to

share your experiences with the

medical physics community,

then please get in touch with

me via email:

[email protected]

Figure 1: Basic block diagram of the PPG processing and data acquisition system. Figure kindly supplied byKarthik Budidha, School of Engineering and Mathematical Sciences, City University, London, UK EC1V 0HB.© IPEM, Budidha K, Kyriacou PA. The human ear canal: investigation of its suitability for monitoringphotoplethysmographs and arterial oxygen saturation. Physiol Meas 2014; 35: 111–28

Figure 2: (A) Infrared AC PPG signals recorded from (a) the ear canal, (b) the right index finger and (c) the leftindex finger of a volunteer. (B) Simultaneously obtained temperature reading from (d) the left index fingerand (e) the right index finger of the same volunteer for a period of 10 minutes. Figure kindly supplied byKarthik Budidha, School of Engineering and Mathematical Sciences, City University, London, UK EC1V 0HB.© IPEM, Budidha K, Kyriacou PA. The human ear canal: investigation of its suitability for monitoringphotoplethysmographs and arterial oxygen saturation. Physiol Meas 2014; 35: 111–28


hours of difficult driving away from Juba, the capital ofSouth Sudan. Several other hospitals in South Sudanhave links with the UK, some around the Wessexregion. Services in Juba are connected to staff at StMarys in the Isle of Wight (where there is a consultantfrom South Sudan) and services in Wau withBournemouth and Poole NHS Trusts. Other links arealso forming.

Initial visitA couple from Winchester have been connected to Yeifor a long time. They came out to work with the churchto improve the Martha Primary Health Care Centreand over several years brought it up to a centre ofexcellence with outreach services to villages and achildren’s ward. They lived in the grounds of YeiVocational Training College (YVTC) and their churchconnections are still very useful to the link. Anelectrical engineer friend of theirs from Winchesterwhose regular work is connected to air traffic control

n a previous issue of Scope readers were told aboutthe link partly funded by the Tropical HealthEducation Trust (THET) between Ghana HealthService for those with cancer and University CollegeLondon Hospital. THET currently funds five medical

equipment partnerships working in Ghana, SouthSudan, Ethiopia, Uganda and Zambia. Their primaryfocus is to build equipment maintenance andmanagement capacity.

This article is about another of these partnerships,‘Repair to Care’, between Yei Civil Hospital (YCH) andthe Martha Clinic in Yei, South Sudan, and HampshireHospitals NHS Foundation Trust. It is very different tothe partnership previously reported, because SouthSudan is a new country created in 2011 after years ofconflict and there is very little infrastructure. Althoughthere is oil there are problems with the pipeline runningthrough Sudan in the north so money is still notavailable for public services as it should be. Yei is in theCentral Equatorial State in South Sudan and is several

I

Nancy MacKeith (Royal Hampshire County Hospital) on a TropicalHealth Education Trust partnership with a hospital in South Sudan

Repair to Care:medicalequipment partnership

Mains switcheswere repaired and plugs

replaced bare wires stuckinto sockets“

“

‘ MOREINFORMATIONTo learn moreabout theprojectscurrently beingfunded by theTropical HealthEducation Trustvisit: http://www.thet.org/hps/resources/medicalequipment/medical-equipment-partnerships-programme


visited them on several occasions and repaired items inthe Martha Clinic and the YVTC.

Our hospital link began with a visit by three doctorsand a midwife doing a fact-finding visit in 2010,obtaining a small grant to help with fares from TheBrickworks, the charity associated with the MarthaClinic. There were about 200 beds in total with medical,surgical, gynaecological, paediatric and maternitywards. It had originally been built by the British in the1900s and had had a good few years of help fromNorwegian People’s Aid. We found YCH had beenrunning with only one doctor. During our stay two newyoung doctors arrived and over the time of the linkthere were more, although numbers at any one timecould vary from one to six. These doctors do anamazing job as they have no senior clinical support andhave to work in every ward of the hospital.

Nurses perform tasks such as cannulation, drugadministration and dressings, and personal care isgiven by relatives who camp outside the ward. Newnurses, midwives and laboratory staff are beginning toqualify from the colleges and a registration system isbeing set up. Staff are paid irregularly but despite thismost remain committed to working at the hospital.There were separately funded wards for HIV, TB andsleeping sickness. It was obvious that they had moreresources and staff. International non-governmentorganisations (INGOs) take responsibility for publichealth services organised on a state-by-state basis. Wethought we should concentrate on hospital paediatricsand maternity on our next visit and include surgerylater when we had appropriate volunteers.

Return visitWe returned a year later with a group of two doctors,three midwives, the electrical engineer who had visitedseveral times before and a chemical engineer who wasthe husband of one of the midwives. We had a smallstart-up grant from THET. A very special aspect of thegroup is that those who feel they are on good salariesbuy their own tickets and visas, leaving any fundingfor those who would otherwise find it difficult to come.

The clinicians worked on the wards and taughtnursing and midwifery students in the training college,which is also on the hospital campus. One of the twoengineers surveyed the water supplies looking at whymost of the plumbed-in sinks on the wards were notworking. He also noticed that some beds lacked frameson which to hang much-needed mosquito nets.Funding was found from the Basic Services Fund topay for the plumber who had previously worked forthe hospital to get the sinks on the wards working andto put up frames on the beds.

Equipment fixed on this visit by the two engineersworking with the hospital electrician included oxygenconcentrators (there are no bottled gases in Yei) andlights for the operating theatres and microscopes. Abiochemistry blood analyser was mended but themachine often cannot be used without up-to-datereagents and test chemicals that are expensive to getand deteriorate quickly. Safety is a huge issue; mainsswitches were repaired and plugs replaced bare wires

PARTNERSHIP FEATURE

stuck into sockets. The town has generators whichsupply the hospital but they go off for 7 hours at night.

We applied to THET and got funding for a 2-yearprogramme known as CARE, looking at howobservations were carried out on patients and used tomanage treatment. CARE stands for collection of data,analysis, reaction and evaluation. We also applied forand were awarded an 18-month Repair to Care grantto support the clinical work. The two programmeshave run side-by-side, so although the clinicians arefunded to come more frequently, they collectinformation to assist the engineers to prepare for theirnext visit.

Fixing electrical equipmentOn the first medical equipment visit funded by THETour electrical engineer, who had been to Yei manytimes, came with another found through personalcontact. An inventory of equipment at the hospital wascarried out, including the contents of a container ofsecondhand medical equipment from the UnitedStates. The electrical equipment was not compatiblewith the voltage in South Sudan. Some of theequipment could be adapted but two transformerswere bought including one for a sophisticatedultrasound scanner which was then used for themanagement of early pregnancy problems. Thehospital’s vital sign machines now work, and webrought out two saturation monitors from LifeBox,one for the hospital and one for Martha Clinic.

Working torepair a shower

s

COVER IMAGE:Workingtogether to fixsupplies

X-raysproduced at YeiCivil Hospital

s

‰


PARTNERSHIP FEATURE

One of the engineers was also a qualified electricianand taught the electrician apprentices at Yei VocationalTraining College. There was no electrician lecturer at thecollege at the time.

On the second funded medical equipment visit, theengineer who is also an electrician came back with a newvolunteer who had plumbing skills. The new volunteerbrought out plumbing tools and equipment and workedwith the new hospital plumber and his apprentice onmapping the water supply as well as identifying andfixing faults. The last part of the THET funds will beused to send out plumbing spare parts and donatedtools. The electrician engineer continued to work withour main South Sudan colleague. His growingconfidence means he now tackles jobs like electronicrepairs that before were outside of his main skillset.

Looking to the futureAwareness about maintenance of equipment before itbreaks down is difficult to establish in a donor-ledsituation. There are signs that this is changing at YCH.An ECG machine was found on the second equipmentvisit and checked for safety by the hospital and visitingengineers. The hospital acting director chose thestorekeeper to be instructed in its use because he ismotivated. The surgical nurse showed him how to use it.

At the end he asked ‘How shall I clean it?’. The linkgroup was much cheered by this.

Our group is constantly impressed with the standardof x-rays produced by the radiographer at YCH. Wehave brought out lead letter markers and special pensfor him to document the films in a more systematic way.The good standard of x-rays meant that the orthopaedicsurgeon and the surgical nurse could run an assessmentclinic for some patients with long-standing orthopaedicproblems found by two INGOs who work withdisability in Yei. The radiographer uses the one ancientmachine that is working. There is a more modernportable one that could replace it but mice and geckoshave chewed through important connectors, and it is aslow process to replace them.

Over time the United Nations Population Fund(UNFPA) and AMREF have sent both long-termvolunteer staff and specialists in, for example, surgeryand ultrasound to use the scanner that our engineersfixed. At national level, VSO have a health programmeand three volunteers came to work in Yei over the timeof our project. One is in County Health, one in thetraining college at YCH and one on the wards. We feelthat our ‘Repair to Care’ project has been part of thesupport our South Sudan colleagues need to carry ontheir work. n

‰

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‘ CONTACTDETAILS

If you would likemoreinformationabout the TheWinchester - YeiHealth, please e-mail CathyWilliams:[email protected] orvisit:http://www.hampshirehospitals.nhs.uk/about-us/global-health-links/the-winchester-yei-health-link.aspx

Get updates from ourPresident. Recent articles fromProfessor Stephen Keevil have

featured the Services AccreditationStandards project, the latest onModernising Scientific Careers andthe new Radiotherapy Board. It islinked from the home page of theMembers’ area on the side menu bar.

Book onto a conference orworkshop. It’s now easier thanever to find out about

forthcoming IPEM events, register, submit anabstract and pay for your place, all online. Just go to

the Conferences and Events pages and click on ForthcomingConferences.

Express your preferences. Help us to tailor yourIPEM communications to suit your needs, by givingus more information about yourself and your

interests. Let us know the topics that interest you and howyou want to be kept informed by going to the Members’area and clicking on My IPEM.

Download outreach resources. Have you got anopen day or a schools event coming up? You candownload ready-made activities, presentations and

careers advice by going to the Careers and Training pageand clicking on Schools in the side menu bar.

Make your opinions count. Respond to our onlinesurveys and polls. We will keep you updated onthem via the newsletter.

Pay your subs. Online payment of subs hasbeen in place for about a year now, but did youknow you can also sign up to pay your subs by

Direct Debit? Once you’re signed up, your subs will bepaid automatically every year, which is easier for you andcheaper for us. The form can be found in the Members’area: click on Forms in the top menu and then Finance inthe side menu. n


WEBSITE FEATURE

More IPEM services and content than ever is now available online.So don’t miss out, take another look at the IPEM website

10 things you can do on thewebsite – www.ipem.ac.uk

Since we successfully linked thewebsite to both our membershipdatabase and our financial system,we have been able to vastlyimprove our web-based services.We’re also adding new contentall the time, which isincreasingly multimedia. So ifyou just use the IPEM websiteto download the odd form,you’re really missing out. Hereare just some of the things youcan now do online.

Take out free equipment loans.IPEM’s equipment library is a growing resource thatcurrently includes a range of phantoms and outreach

material. Book them out free of charge from theMembers’ area of the website. Go to the Training andOther Resources page and click on Equipment Library in theside menu bar.

Network with your peers. IPEM’s online groupsare a new way to link with your colleaguesnationwide and join in the discussions of the day.

Our member forums enable you to chat to other membersin your region or specialism. Go to the Members’ sectionand click on Forums in the top navigation bar. TechNet isan open network for those employed in technical rolesrelated to healthcare applications. The link can be foundon the side menu bar of the Professional Matters page.

Find out who’s who. You can find out who’s whoon our committees by downloading the completelist from the Members’ area: follow the Committees

& Groups link under the Members and Networking sectionon the homepage. To find IPEM staff, click on Contact Usand follow the link in the side menu bar. Coming soon isa searchable membership directory.

Catch up with your training. Our online trainingsupport includes learning modules, conferencewebcasts, CPD guidance notes and (for full

members only) free access to the extensive resources ofCMI’s Management Direct system. Find them on theTraining and Other Resources page in the Members’ area.Coming soon is online CPD recording.

1

9

2

3

4

Visit thewebsite now tosee the newcontent andfeatures

▼

‘ CONTACT USSome of these services are in the Members’ only area. But don’tfret if you can’t remember your log in details, just contact us [email protected].

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sinogram. Onboard imaging, used for daily IGRT, isprovided via a helical megavoltage CT (MVCT) systemwith an unfocussed detector array which must be qualityassured for both image quality and Hounsfield unit (HU)calibration when used for dosimetric checks of patientdeliveries. Patient set-up is achieved by aligning patientreference marks with a set of moveable red lasers in thetreatment room. A second set of lasers (green) mark thecentre of the bore. In addition to all of these components,software and hardware updates are released frequentlyrequiring Tomotherapy QA systems to be monitored andchanged/updated regularly.

Tomotherapy units are serviced every two weeks byfield service engineers (FSEs). Under normal conditions,the FSE gathers data from the unit to demonstratecontinued performance or to determine errors and, afterset periods of beam-on time, performs specific services

omotherapy is a radiotherapy systemdesigned to give very high quality intensity-modulated radiotherapy (IMRT) with image-guided radiotherapy (IGRT) in a helicalmanner. During treatment, the patient is moved

through a rotating gantry on a couch while the radiationbeam is modulated using binary multileaf collimators(MLCs). To date, seven radiotherapy centres in the UKhave begun using this system; each centre having eitherone or two treatment units.

Tomotherapy is a unique system on which to performquality assurance (QA) due to the helical nature of thetreatment delivery. Linac pulsing, couch drive and MLCpositions are synchronised with gantry rotation which ismeasured using an optical system. Treatment plans thatincorporate these parameters are inversely optimised andcharacterised by their MLC opening sequence or

Image ©AccurayIncorporated(2014)

t

Jim Daniel (The James Cook University Hospital, Middlesbrough) and Sam

Tudor (Addenbrookes Hospital, Cambridge) surveyed current practice

Tomotherapy qualityassurance survey in the UK

T

6 MV linac

Primary collimator

MLC

Beam Stopper CT Imaging Detector768 Xenon cells


QA SURVEY FEATURE

that include imaging, mechanical and computinghardware checks. The data gathered are used to observechanges in output and beam quality, the latter beinguseful for indicating target wear and thinning.1 This datacan also be collected by the physics group in a hospitalvia the use of Tomotherapy QA (TQA) software. The TQApackage uses the onboard imaging detectors and externalmeasurement tools to collect data and plot trends that canbe useful in predicting (and hence, aid the avoidance of)future problems.

To the medical physicist working with Tomotherapy, itis not immediately clear how to set up and maintain a QAsystem for such a distinctive radiotherapy treatmentmachine, and to date there has been no UK-specificguidance available. Physicists involved withTomotherapy have previously taken advice from varioussources,2,3 including guidance from the AmericanAssociation of Physicists in Medicine (AAPM),4 but haveultimately developed their own QA systems.

A future IPEM report will contain recommendationsfor Tomotherapy QA. In order to develop a framework inwhich to make appropriate recommendations for thisreport, a survey of current practice was sent out to UKradiotherapy centres that have Tomotherapy treatmentunits. The results of this survey, along with a discussionof their implications, are presented here.

Questionnaire designIn September 2012, a questionnaire was sent out via emailto the heads of radiotherapy physics departments thathave Tomotherapy treatment units. The questionnairewas designed to collect data about the current techniques,frequencies and tolerance levels for QA procedures onTomotherapy units in the UK and was split into foursections with subsections (table 1).

Each subsection was divided into questions relating tospecific QA tasks. For the majority of QA tasks, thequestions asked were ‘performed?’, ‘frequency’,‘tolerance’ and ‘brief method’.

Where it was helpful to have extra information, morequestions were asked about certain QA tasks. Forexample, under the QA task ‘static output’, the specificdepth at which measurements were made, phantommaterial and beam dimensions were also requested.

Space for answers to the questions was left blank toenable users to give as much detail as possible and toacknowledge the relative uncertainties about how best toperform Tomotherapy QA. For example, certain QA taskssuch as ‘longitudinal profiles’ were often specified asbeing done at two different frequencies with differentmethodologies and so an open response method wasuseful. This approach also allowed the varied andinnovative approaches to Tomotherapy QA to berepresented. Many users have developed QA usingconsistency check devices or various other tools that werealso easily included using this approach.

MethodsThe results of the questionnaire were compiled in anExcel spreadsheet. Responses to each question wereanalysed individually and summarised, which allowed aqualitative analysis of the general agreement of the test in

TABLE 1.Questionnairesections andsubsections

t

question. Some tests such as static output and dailyconstancy check overlapped, as the static beam was usedas the daily check by some centres, and these situationswere noted.

Each test was also quantified by how often it wasperformed. The letters D, W, BW, M, Q and A wereassigned to indicate daily, weekly, bi-weekly(fortnightly), monthly, quarterly and annually testingfrequencies. C and R were used to refer tocommissioning only and after repair in those responsesthat indicated tests were performed, but not routinely. Ewas used to indicate a response of every patient where itwas felt that the QA test in question was beingperformed every time a patient plan was produced. Thisenabled analysis of how much QA was being performedat the various centres and how similar the QAprogrammes were to each other. Other frequencies werealso noted, such as bi-annually and following upgrade.

In order to establish the agreement around whethertasks were generally either performed or not by themajority of UK Tomotherapy users, a measure ofconsensus was defined in the following way. For eachsubsection of the questionnaire, the number of questionsthat all or all but one of the centres agreed was taken as apercentage of the total number of questions in thatsubsection. A low value of consensus within a subsectionindicated disagreement amongst centres about what QAwas necessary. A consensus value of 100 per centindicated that the majority of centres agreed about whatQA should be done. Note that frequency and methods oftesting were not taken into account for this measure,simply whether the QA tasks were performed or not.

ResultsSix of the seven centres approached responded to thequestionnaire. Of these centres, four have a singleTomotherapy unit and two have two units.

Consensus data have been graphically representedusing bar charts (figures 1, 2 and 3). Superimposed oneach graph is the fractional value of consensus; thenumber of QA tasks in the group that all or all but one

TABLE 1

Section Subsections

Machine QA Output and drift

Mechanical alignment

Beam properties

Couch

Interrupted procedures and TQA

Geometric verification and imaging QA Geometric accuracy

Imaging dose

Image quality

Patient QA Patient QA

Planning system QA Image transfer

Other component transfer

End-to-end testing

‰


QA SURVEY FEATURE

centre reported as being performed regularly dividedby the total number of QA tasks within the group. PatientQA and planning system QA (sections C and D) havebeen grouped together (figure 3).

Section A – machine QAThere were 22 questions in section A that focussed on QAtasks on machine components involved in treatingpatients including output and energy measurements,gantry synchronicity with the MLC and couch, sourcealignment with the jaws and MLC, beam profiles, couchmoves and the ability of the system to complete aninterrupted delivery.

Output checksThere were a variety of approaches adopted formeasuring treatment beam output. All of the centresmeasured output in both static and rotating gantrymodes, but there was no agreement regarding whichshould be used daily, nor was there a standard method ofmeasuring either mode of output. However, all centresdid agree that a daily output measurement was necessaryalongside another output check performed at a lowerfrequency. Calibrated ionisation chambers, constancycheck devices and onboard detectors all formed part ofthe QA process.

In addition to measuring the outputs, all centresperformed some measure of the rotational variation ofoutput with gantry angle, either through the bi-weeklyFSE visit or by a separate measurement with anionisation chamber.

Mechanical alignmentAlignment QA includes synchrony of the couch and MLCwith gantry angle, source alignment with jaws and MLC,y-jaw divergence and beam centring, MLC alignmentwith the central axis of the beam and field centring acrossall field width settings. Except for MLC and gantrysynchrony, which can also be said to be a measure ofgantry angle determination, and MLC alignment with thebeam central axis, these tests were performed by all ofthe responding centres.

From table 2, it can be seen that centres 1, 3, 5 and 6have a similar set of testing frequencies, with theminimum being that of centres 1 and 3. Centre 4 wassimilar but did not include alignment of MLCs withcentral axis. Centre 2 did not routinely perform this set ofQA measurements.

Beam propertiesProfiles in both transverse and longitudinal orientationsand beam energy are included in this section. All centresexcept one performed all of these tests routinely.

Table 3 demonstrates that there was a consensus interms of testing frequency of beam profiles and energy.Where two frequencies are indicated, this shows that thecentre performs some form of constancy check regularlyalongside less frequent, but more definitive,measurements. For example, centre 3 performedlongitudinal profiles monthly using film, but used thewater tank on a quarterly basis to check against goldstandard data.

TABLE 2

Centre

1 2 3 4 5 6

Gantry angle determination Q Q Q M M

Couch/gantry synchronicity Q C Q Q M M

Alignment of source with jaws A R A A M A

Alignment of source with MLCs A R A A M A

Y-jaw divergence/beam centering test A R A A A A

Alignment of central axis of different jaw settings A R A A A A

Alignment of MLCs with central axis A R A A A

TABLE 3

Centre

1 2 3 4 5 6

Profile in longitudinal direction M/A R M/Q W M M

Profile in transverse direction BW/A R Q M M M

Energy (PDD/other beam quality check) W/A W W/Q W M/A W/M

TABLE 4

Centre

1 2 3 4 5 6

Green laser position vs centre of image set D W M Q

Green laser position vs treatment beam A W M M A

Direct comparison of treatment centre and imaging centre A W

Red laser position at zero offset D D D D D D

Red laser position at non-zero offset D W D D M D

TABLE 2. Frequency responses to mechanical alignment section

TABLE 3. Frequency responses to beam properties section

TABLE 4. Frequency responses to geometric accuracy section

FIGURE 1. Consensus data for machine QA

t

t

t

t

‰


QA SURVEY FEATURE

Energy was expressed as a ratio of doses at twodifferent depths in a static field in solid water; fivecentres used a percentage depth dose (PDD) approachand one centre used a tissue-phantom ratio (TPR)method. All centres used a 5 cm wide field, four centresused all MLC open, one centre used a 20 cm field and onecentre used a 10 cm field. All centres except one used a 1per cent tolerance limit on this measure.

CouchCouch testing included level (pitch, roll, yaw), sag, driveaccuracy (step moves/upon pressing set-up) and driveuniformity and accuracy during treatment. These testswere uniformly adopted by all centres except for couchsag, which was not directly tested by two centres.

OtherThis section of machine QA included a question oninterrupted procedures and one regarding the use of theTQA package. Four centres performed interruptedprocedure testing using delivery QA devices: three withDelta4 (ScandiDos, Uppsala, Sweden) and one withMatriXX (IBA Dosimetry GmbH, Schwarzenbruck,Germany).

Four centres responded to say that they had someexperience of TQA and of those four, three centres saidthat they used it as a routine part of the QA programme.There was some hesitation regarding its reliability withtwo of the centres that use it regularly reporting that theyonly rely on certain aspects of it to inform about the stateof the machine. In particular, energy and exit detectorparameters were mentioned as being unreliable at times.One centre reported using TQA on a regular basis fordaily output checks.

Section B – geometric verification and imaging QASection B contained 13 questions regarding the imagingcharacterisation, geometric coincidence of imaging andtreatment isocentres and the laser systems.

Geometric accuracyRed laser QA was performed as standard by all centresdaily, generally to within a tolerance of 1 mm. One centreused a 2 mm tolerance and two centres performed redlaser QA with a positional offset less frequently. Greenlaser QA was performed using various methods at arange of frequencies, from daily to quarterly.

The final two tests in this section comprised testing thegreen lasers against the treatment isocentre and a directcomparison of the imaging and treatment isocentres.Table 4 shows the responses to these two sections.Methods used to make these measurements included filmand detector arrays.

Imaging doseImaging dose was monitored periodically by five of thecentres at a frequency ranging from weekly to annually.One centre performed this test only when a repair orupgrade may have affected the imaging system.Tolerances applied to the test were of two varieties: eithera measure less than an absolute value (3 cGy) or ‰

TABLE 6

Centre

1 2 3 4 5 6

Dimension checks U A A Q

Voxel size transfer U A

Image orientation U A E A Q

HU transfer U A Q

Associated plan notes transferred E A M

Structure dimensions transferred E A U

Structure location transferred A A U

Structure orientation transferred E A U

End-to-end testing A A A U

End-to-end testing (dose distribution) U A U

TABLE 5

Centre

1 2 3 4 5 6

HU accuracy W/M R W/Q M M W

Image scaling (in-plane) M C Q M M M

Image scaling (longitudinally) M M M M

Uniformity M C Q M M M

Noise and/or contrast to noise ratio M C Q M M

In-plane spatial resolution M C Q M M M

Longitudinal spatial resolution C

TABLE 5. Frequency responses to image quality section

TABLE 6. Frequency responses to planning system section

FIGURE 2. Consensus data for geometric verification and imaging QA

t

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QA SURVEY FEATURE

REFERENCES

1 Staton RJ, Langen KM, Kupelian PA, Meeks SL.Dosimetric effects of rotational output variation andx-ray target degradation on helical tomotherapyplans. Med Phys 2009; 36: 2881–8.

2 Fenwick JD et al. Quality assurance of a helicaltomotherapy machine. Phys Med Biol 2004; 49:2933–53.

3 Balog J, Soisson E . Helical tomotherapy qualityassurance. Int J Radiat Oncol 2008; 71(S1): S113–17.

4 Langen KM et al. QA for helical tomotherapy: reportof the AAPM Task Group 148. Med Phys 2010; 37:4817–53.

5 Thomas SJ et al. Reference dosimetry onTomoTherapy: an addendum to the 1990 UK MVdosimetry code of practice. Phys Med Biol 2014; 59:1339–1352.

‘ ACKNOWLEDGEMENTSWe would like to thank those who took the time to complete andreturn these surveys.

Discussion and conclusionsQuality assurance on Tomotherapy machines is performedin a variety of ways at a range of frequencies across theUK. The majority of QA tasks addressed in this surveywere performed routinely by at least five out of six of thecentres within the machine, geometric verification andimaging and patient QA sections. Results in the planningsystem QA section show that there is currently noagreement about what should be tested routinelyregarding the Tomotherapy planning system. Whereagreement was found in the routine performance of QAtasks, there were differences in the frequency in whichthose tasks were carried out; QA tasks carried out by onecentre on a weekly basis were carried out quarterly byanother.

Guidance is available to help produce QA systems inthe form of Tomotherapy’s own physics course notes andthe AAPM document TG148.4 Some of the QA tasksperformed by the centres appear to have been adopteddirectly from this guidance, such as the y-jawdivergence/beam centering test, which all centres performidentically using the same tolerance levels. The fact that allUK centres perform this test in exactly the same wayprovides evidence that the production of a QA system forTomotherapy can be difficult and can certainly benefitfrom good quality guidance. Producing a standardised QAsystem is also complicated by the fact that Tomotherapydoes not necessarily build on the previous experience ofradiotherapy physicists, competent and familiar withconventional linear accelerators, and so there is diversityin the range and amount of QA currently being performed.

The Institute of Physics and Engineering in Medicine(IPEM) is producing guidance on how to construct aTomotherapy QA protocol. When used in conjunction with the recently published Tomotherapy code of practice,5

this document will provide a framework to assist the UKcommunity in constructing QA systems for Tomotherapy.n

an accepted difference of 5, 10 or 20 per cent from abaseline measure.

Most centres used a calibration factor for the treatmentbeam to measure the imaging dose with anacknowledgement that there would be some small errorinvolved, but that this was justified as the accuracy of thismeasurement was not as critical as an outputmeasurement.

Image qualityWhere two frequencies were specified for HU accuracy,the weekly QA was a simple check of ‘water’ HU in theCheese phantom (a cylindrical solid water phantom withholes to hold ionisation chambers), with the second testfrequency used for a more comprehensive test of HUacross the clinical range of values. Longitudinal spatialresolution was not tested routinely by any centre (table 5).

Section C – patient QAThis section related to patient-specific QA delivered to aphantom with film or some form of detector array tomeasure the absolute and relative doses, ensuring thatplans can be delivered as expected.

All centres perform patient QA. One centre reportedthat they do not perform QA on every patient but insteaduse in-house software to recalculate doses in order tocheck the plan. Four centres used the Delta4 phantom forDQA purposes, one centre used Octavius (PTW, Freiburg,Germany) and one primarily used the Cheese phantomwith film. There were a variety of gamma tolerancesspecified, ranging from 90 per cent gamma at 3 per cent, 3mm to 98 per cent gamma at 3 per cent, 2 mm.

Regarding the transfer of plans between units, one ofthe centres applies criteria based on the anatomical siteand number of fractions to be delivered on the other unit,while the other performs patient QA on every plan whichis transferred.

Section D – planning system QATable 6 contains the frequency responses from this section.Where E is indicated in the table, the centre indicated thatthe test was effectively being done through the normalplanning process for each patient.

FIGURE 3.Consensusdata for patientQA andplanningsystem QA

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n the past few decades, computed tomography (CT)and cone-beam computed tomography (CBCT) havebeen used in all kinds of diagnostic and treatmentprocedures worldwide and have proved clinicallyeffective.

1, 2However, the radiation dose from CT and

CBCT scans has been a concern among clinicians and thegeneral public,1 particularly in paediatric patients as theyare far more susceptible than adults to radiation-inducedlate effects such as growth retardation and secondmalignancies, etc.3

Unfortunately, modern radiotherapy treatmentplanning systems (TPS) do not offer CT/CBCT dosecalculation capability. Although the Monte Carloalgorithm can be used to simulate the radiation dosefrom CT/CBCT scans, it is very time consuming andusually requires Monte Carlo expertise. Hence, it wouldbe highly desirable to have an easy-to-use tool that canbe used to estimate the radiation dose from an imagingprocedure performed on a specific individual.

Why an iPhone app?As the Apple iPhone is highly popular around the world,an iPhone app designed for such a purpose would beideal to maximise its accessibility to the general public aswell as medical practitioners. In October 2011, a newiPhone app project named CT Gently was initiated anddeveloped jointly by my group and Komatsu BusinessService Co. in Tokyo, Japan. As planned, CT Gently wasdeveloped with Apple Xcode 4.2.1 toolkitswith all the functionalities runningon an Apple iPhone platform. TheAndroid and Windows-basedversions of CT Gently are expected inthe near future.

Interface designThe philosophy for the interface designis simplicity and efficiency. After theuser enters gender, age, weight,corresponding circumference at threeanatomic sites (i.e., head, chest andabdomen) and given mAs and kVp values,CT Gently can generate comparativeresults both quantitatively and graphicallyon the organ doses and the associated cancer risks between the reference and the optimised settings for aCT or CBCT scan. It also allows the user toswitch the units for weight and lengthbetween the international standard and theEnglish system. In addition, a unique questionand answer (Q&A) page can be accessed easilyfor some simple explanations on the basic termsand concepts such as CT, CBCT, mAs, kVp,organ dose and relative risk, etc.

Currently, CT Gently reports organ dosedirectly instead of CT dose index (CTDI), and itonly calculates dose and relative risk for oneorgan per scan site; that is, the brain for headscans, the lung for chest scans and the red bonemarrow for abdominal scans. More organs will beincluded in the future to expand this functionality.

Organ dose and cancer riskBased on Monte Carlo modelling of the CT and CBCTscans and particle transport simulation in humananatomy of various dimensions, the radiation doses tothe various organs-at-risk in the head, chest andabdomen regions can be obtained for a specific scan ofgiven mAs and kVp values.4–11 Furthermore, personalisedestimation of organ dose has been made possible basedon some cohort studies investigating the correlationsbetween the organ dose and one’s weight andcircumference, mAs and kVp of the specific scan.8–11

Finally, these correlations between organ dose and thescan settings as well as anthropometric parameters havebeen formulated and implemented in CT Gently tofacilitate the calculation of organ dose.

Besides reference settings of mAs and kVp, a scanoptimiser has been implemented to generate theoptimised mAs and kVp settings for low-dose CT andCBCT scans based on the user’s input. The optimiserworks in such a way that an almost constant low dosehas been maintained for the specific organ-at-risk withuniform noise property, irrespective of one’s physicaldimension. In general, the optimised settings yield a dosereduction of 50–80 per cent incomparison to the referencesettings, which are the pre-

PERSONALISED DOSE FEATURE

How the dosecalculation isdisplayed by theapp

▼

I


‰

PERSONALISED DOSE FEATURE

REFERENCES

1 Brenner DJ, Hall EJ. Computed tomography: anincreasing source of radiation exposure. New Engl JMed 2007; 357: 2277–84.

2 Dawson LA, Sharpe MB. Image-guidedradiotherapy: rationale, benefits, and limitations.Lancet Oncol 2006; 7: 848–58.

3 Pearce MS et al. Radiation exposure from CT scansin childhood and subsequent risk of leukaemia andbrain tumours: a retrospective cohort study. Lancet2012; 380: 499–505.

4 Angel E et al. Dose to radiosensitive organs duringroutine chest CT: effects of tube currentmodulation. Am J Roentgenol 2009; 193: 1340–45.

5 Reid J, Gamberoni J, Dong F, Davros W.Optimization of kVp and mAs for pediatric low-dosesimulated abdominal CT: is it best to baseparameter selection on object circumference? Am JRoentgenol 2010; 195: 1015–20.

6 Zhang Y, Li X, Segars WP, Samei E. Organ doses,effective doses, and risk indices in adult CT:comparison of four types of reference phantomsacross different examination protocols. Med Phys2012; 39: 3404–23.

7 Lee C, Kim KP, Long DJ, Bolch WE. Organ doses forreference pediatric and adolescent patientsundergoing computed tomography estimated byMonte Carlo simulation. Med Phys 2012; 39:2129–46.

8 Zhang Y, Yan Y, Nath R, Bao S, Deng J. Personalizedestimation of dose to red bone marrow and theassociated leukaemia risk attributable to pelvic kilo-voltage cone beam computed tomography scans inimage-guided radiotherapy. Phys Med Biol 2012; 57:4599–612.

9 Zhang Y, Yan Y, Nath R, Bao S, Deng J. Personalizedassessment of kV cone beam computed tomographydoses in image-guided radiotherapy of pediatriccancer patients. Int J Radiat Oncol 2012; 83:1649–54.

10 Deng J, Chen Z, Yu JB, Roberts KB, Peschel RE,Nath R. Testicular doses in image-guidedradiotherapy of prostate cancer. Int J Radiat Oncol2012; 82: e39–47.

11 Deng J, Chen Z, Roberts KB, Nath R. Kilovoltageimaging doses in the radiotherapy of pediatric cancerpatients. Int J Radiat Oncol 2012; 82: 1680–68.

12 National Research Council. Health Risks fromExposure to Low Levels of Ionizing Radiation: BEIRVII – Phase 2. Committee to Assess Health Risksfrom Exposure to Low Levels of Ionizing Radiation.Washington, DC: National Academies Press, 2006.

13 Goske MJ et al. The 'Image Gently' campaign:increasing CT radiation dose awareness through anational education and awareness program. PediatrRadiol 2008; 38: 265–9.

14 Brink JA, Amis ES. Image Wisely: a campaign toincrease awareness about adult radiation protection.Radiology 2010; 257: 601–2.


defined settings from a scan protocol, or from themanufacturer, or any scan settings indicated by the user.

Currently, CT Gently only generates one set ofoptimised settings (mAs, kVp) based on one’scircumference, which is basically a balanced approach tocutting the organ dose whilst maintaining acceptableimage quality. In the future, two more optimisationscenarios may be added to suit different clinical needs, i.e.to better spare the organ or to achieve better imagequality.

Using BEIR VII formulism,12 we first estimate theradiation-induced excess relative risk (ERR) based onone’s gender, age and radiation dose to a certain organ-at-risk from a CT or CBCT scan. The relative risk (RR) is thenreported as 1+ERR in our app. Qualitatively speaking, therelative risk stands for the excessive cancer risk related tothe radiation exposure to a group of individuals, ascompared to the group without radiation exposure.

Inclusion in Apple App StoreThe first version of CT Gently was uploaded into theApple App Store on 30th May 2013, but the final approvalwas granted later on 20th June 2013, slightly longer thanthe normal review process which usually takes a week.The delay was caused by Apple’s request that the sourcesof the medical information included in the app beprovided. After the required documents were submitted,our app was soon put online. Recently, based on initial

‘ ABOUT THEAUTHORJun Deng, PhD,FInstP, FAAPM,is an AssociateProfessor in theDepartment ofTherapeuticRadiology of YaleUniversitySchool ofMedicine, NewHaven, CT, USA,and an ABRboard-certifiedmedicalphysicist at Yale-New HavenHospital.

‰ feedback from users, we revised our app and uploadedversion 1.01 to the App Store on 15th August 2013. Thewhole review process was a breeze this time and onlytook 2 days.

ConclusionsWe have developed CT Gently, the world’s first iPhone app of its kind that can be used to estimateorgan doses and associated cancer risk from CT andCBCT scans based on individual anatomy and scanmode. Furthermore, this easy-to-use app can be used togenerate optimised settings for personalised low-doseCT and CBCT scans. With the increasing concern ofradiation dose and cancer risk among clinicians and thegeneral public, especially to children, we believe CTGently may help increase awareness about the safe andappropriate application of medical imaging in the clinic with improved benefit-to-risk ratio in the longrun, aiming to achieve the same goal as the ‘Image Gently’ and ‘Image Wisely’ campaigns.13,14

We believe CT Gently may helpincrease awareness about the

safe and appropriate applicationof medical imaging“

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detection and childhood epilepsy (figure 1). ‘Thetechnology is working well,’ Robin says. ‘We’re nowworking with a local 3D printing company to developbone-simulating plastics for use in our phantoms.’

Project: Ultrasound bladder scanning forradiotherapy planningDr Gareth Webster, University Hospitals BirminghamNHS Trust Radiotherapy for prostate cancer can cause side-effectsdue to irradiation of the small bowel. Drinking protocolsare often used to increase bladder volume and lift thebowel away from the high dose region. However,compliance can be poor, resulting in excess irradiationfrom rescans and daily delays to treatment. Using IPEMfunding, Gareth Webster purchased an ultrasound probethat quickly measures bladder volume and tested itspotential to identify problems prior to scanning ortreatment. ‘We’ve found that the system is accurateenough to assess whether clinical drinking protocolshave been followed adequately,’ said Gareth. ‘Patientsbenefit from fewer delays and reduced imaging dose.Although it takes time to scan each patient, this is largelyoffset by the reduced CT rescan rate.’ The results will bepresented at the conference of the European Society forRadiotherapy and Oncology (ESTRO) in 2014 and apublication is in preparation.

Project: Widening access to self-administeredpain reliefRichard Axell, Addenbrookes Hospital, Cambridge For many health conditions, it is often best to let thepatient administer their own pain relief. Patientcontrolled analgesia (PCA) has been found to be moreeffective at relieving pain and has lower and thereforeless costly nursing requirements than pain reliefcontrolled by nurses. However, an estimated 20 per centof patients who would benefit from PCA are physicallyunable to operate the handsets. Richard Axellsuccessfully applied for IPEM funding to develop andassess three prototype PCA activation systems fordisabled patients. Working in collaboration with acompany that manufactures PCA pumps, the Cambridgeteam have looked into the use of push buttons, puff tubesand sphyg bulbs as possible activation mechanisms.They have produced the first prototype handsets (figure2) and are now testing them with patients. ‘We believethat, with the right handsets, almost every patient shouldbe able to access PCA,’ says Richard.

ack of funding is a real barrier for researchand innovation projects in healthcare,particularly local projects that are at an earlystage, speculative or niche. Such projectssometimes stall for the lack of relatively small

amounts of funding to buy equipment or commission aprototype. IPEM’s Research and Innovation Awards aimto bridge this gap, by providing short-term researchprojects with up to £10,000 for equipment or services.2012 was the first year of the scheme and £46,000 wasawarded to six successful applicants. They have nowreported back with innovative developments andsignificant results, such as 3D printed phantoms, betteraccess to pain control and the first UK production of amedically valuable radioisotope. Two of the awardwinners have successfully applied for personalfellowship awards with the help of their IPEM-fundedresearch activities. Read more from the winners below onhow the funding has helped their research and wheretheir projects are now.

Almost £50,000 was awarded to nine successfulapplicants in 2013. The 2014 round of applications willopen in late summer and the total fund available hasbeen increased to £100,000. We welcome applicationsfrom all our membership. So start thinking now aboutwhether IPEM funding is what you need to help yourresearch project on its way.

Project: Better brain phantoms from a 3DprinterDr Robin Holmes, University Hospitals Bristol NHSFoundation TrustThe range of possible applications for 3D printers israpidly widening as the technology becomes faster,cheaper and more sophisticated. Robin Holmes wasinterested in the potential of 3D printers to produceanatomically correct brain phantoms for use withpositron emission tomography (PET) scanners andgamma cameras. Phantoms are test objects used for thequality assurance of medical imaging systems. Their useis vital to ensure that differences between scans are dueto differences in the patients and not due to variations inscanner performance. With better phantoms, scanreporting for conditions such as neurodegenerationbecome more objective and accurate, reducinguncertainty and enabling earlier diagnoses. The Bristolteam used IPEM funding to buy paper and 3D printingsystems, which they have used to produce specialisedbrain phantoms for research projects on dementia

L

Elspeth Bartlet (External Relations Manager) and David Brettle (PresidentElect) report on how IPEM funding is helping healthcare research

IPEM’s Research &InnovationAwards

‘ YOUR LETTERSScope welcomesyour feedback!

If you wish tocomment on thisfeature oranything else inScope, emailyour say toUsman([email protected] [email protected])


Project: Accurate detection of bone micro-fractures in young childrenMr Stephen Rimmer, Leeds General InfirmaryThe Leeds team wanted to improve the accurate x-raydetection of tiny fractures, called classic metaphyseallesions, in the bones of children under two. This type ofinjury is associated with physical abuse, so theiridentification is important and a misdiagnosis could haveserious consequences. An IPEM award, together withfunding from other charities, purchased a new bornphantom for measuring and verifying radiation doses.This enabled the group to develop evidence-basedradiographic guidelines, which they plan to publish laterthis year. ‘These guidelines will help radiographic teamsimprove their accuracy and reduce the x-ray dose neededfor vulnerable young patients,’ explains Stephen Rimmer.They are now using the phantom for a second project oncardiac problems in young patients.

Project: A solid target holder for producingthe radioisotope Yttrium-86Dr Christopher Marshall, Cardiff UniversityThe radioactive drug Yttrium-90 (90Y) is widely used fortreating cancers, such as neuroendocrine tumours. Itsdistribution and behaviour in the body can be trackedand measured using the positron emitting radioisotopeYttrium-86 (86Y). Radiotherapists and researchers need 86Yto assess 90Y treatments and to develop new, targettedcancer treatments using radiolabelled monoclonalantibodies. IPEM funding paid for the design andproduction of a solid target holder used to make 86Y. Withthe help of this specially commissioned equipment, theWales Research and Diagnostic PET Imaging Centre(PETIC) has succeeded in producing 86Y in the UK for thefirst time. ‘Producing this important radionuclide willimprove this country’s PET research infrastructure,’ saysChris. ‘Not only will we be able to make the 86Y we needfor our own research in Cardiff, but we will be able tosupply other UK PET centres.’

Project: A non-invasive way to detect andcharacterise cardiac arrhythmiaDr Fernando Schlindwein, University of LeicesterIrregular heart rhythm (cardiac arrhythmia) is a majorcause of illness and death in the UK. Researchers areattempting to obtain information about the electricalfunction of the heart from measurements of electricalpotential at the body surface: the inverse problem ofcardiology. Such a non-invasive system would beinvaluable to help clinical decision making and improvethe cost effectiveness of heart catheterism. FernandoSchlindwein used funding from IPEM and other sourcesto buy a body surface potential mapping (BSPM) systemfrom the Netherlands. ‘With the new BSPM system wecan attach up to 128 electrodes to the body surface,’ saysFernando. ‘This high spatial definition allows for asignificantly improved analysis of atrial fibrillation.’ Intrials involving heart rhythm patients, the Leicester teamare now using the new system, together with anatomicalinformation obtained by magnetic resonance (MR)scanning, to try and solve the inverse problem ofcardiology (figure 3). n

RESEARCH AND INNOVATION FEATURE

FIGURE 2. A prototype handset

FIGURE 1. Phantom produced from a 3D printer

FIGURE 3. Mapping body-surface electrical potential


ACCREDITATION FEATURE

diversification of UK Masters courses in medical physicsand biomedical engineering. A retrospective survey ofprogramme leaders showed that only around 40 per centof UK graduates from these MSc courses seek same-sector employment in the NHS or private hospital sector.Of the remaining 60 per cent, around half seekemployment in industry, while the other half enter theacademic sector via further study, research or anacademic appointment.

Three stakeholder requirementsA working group chaired by Professor Dick Lerski wassubsequently approved by the IPEM council to begindeveloping a new framework for Masters level courses.Three stakeholder requirements defined its subsequentdevelopment and were the starting point onto the blanksheet of paper (in reality, a blank whiteboard) that beganthe process.

The first requirement was for greater flexibility forHEIs to tailor their course content to local strengths suchas staff expertise and research specialisation. Thisrequired careful balancing of framework design toensure that core content within physics or engineeringfields, that stakeholders believed would remain essentialknowledge and skills for a graduate biomedical engineeror medical physicist, remained in place.

The second requirement was better linking of theframework to graduate employability, with accreditationserving as a ‘kitemark’ of educational quality andsuitability for employers in academia and industry, aswell as the NHS sector.

Addressing the growing interdisciplinarity withinstudent cohorts was the final stakeholder requirement,thus allowing accreditation to be inclusive and relevantto students with a first degree outside physics orengineering. This includes up-skilling and re-skillingstudents looking to build new skills or transfer acquiredskills from one sector of engineering or science, and alsoniche sectors where strong private sector demand isfound in training for medical applications. Examplesinclude computer scientists working on the evergrowingsoftware development side of biomedical engineering.Graduates from this background require knowledge andunderstanding of the fundamental scientific principlesthat govern the hardware they programme. Anotherexample is medical graduates, particularly fromoverseas, who are seeking training and knowledge inmedical physics or biomedical engineering prior toapplying for fellowship-level training.

ver the past two decades, IPEM administeredan accreditation process for MSc coursesteaching physics and engineering withapplications in medicine or biology. Thisprocess closely fitted the charitable objectives

of the Institute and was well regarded in the sector; by2012 there were 20 accredited programmes, from a totalof 15 Higher Education Institutes (HEIs) across the UKand Ireland. In addition, there was overseas accreditationof the University of Malaya’s MSc in Medical Physics.

The accreditation process is described in Chapter 5 ofthe Institute’s Training Prospectus for Medical Physicists andClinical Engineers in Health Care (ISBN: 1903613256,version 5, 2010). More commonly referred to as the ‘IPEMblue book’, this publication outlines a framework for theassessment of relevant MSc courses with the aim ofaccrediting courses delivering ‘a knowledge base suitablefor the IPEM Training Scheme’ to an appropriatestandard.

Since 2010 there have been significant changes to thetraining of healthcare scientists and engineers in Englandand Wales. These changes make the old IPEM TrainingScheme for NHS clinical scientists and engineers widelyredundant for the hospital employment sector. Moreover,widespread changes to the UK higher education fundinglandscape, together with increased internationalisation ofHEI classes and growing university–industrialpartnership activity have led to significant numbers ofcourses targeting students with employment aspirationsoutside the NHS arena. This is particularly true inbiotech-centred areas of bioengineering in sectors such asimplant devices, tissue engineering and biomedicaloptics, where the UK has a critical mass of small tomedium enterprises (SMEs).

Starting at the beginningThis diversification of employment routes wasimmediately apparent at a York roundtable meeting of 17programme leaders in November 2012, called to discussIPEM’s role in accrediting postgraduate courses. At thismeeting, it was evident that a strong demand currentlyexisted for IPEM to continue accreditation at Masterslevel, despite competitive activities from otherprofessional bodies. However, a new framework wasneeded that offered a wider vision to be inclusive of thewhole medical physics and bioengineering community.So a ‘blank sheet of paper’ approach was adopted todesigning a new framework.

One key observation at the meeting was the growing

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Jamie Harle, Tony Evans, Dick Lerski and Liz Parvin are involved indeveloping a new assessment scheme for Masters level courses

IPEM accreditationframework for MSc courses





‰

FIGURE 1. Members and invited guests at a 2013 meeting of the working party. Present, from the left, are: Cathy Brown (IPEM), Tony Evans (Leeds),Slavic Tabitov (KCL), Anthony Bull (Imperial), Dick Lerski (Dundee), Fernando Schlindwein (Leicester), Liz Parvin (OU) and Jamie Harle (UCL)

FIGURE 2. The Masters level accreditation framework



engineering and a physics stream.. To encourageflexibility, the subject areas themselves serve only as aguide to the structure of a Masters course, and HEIs arefree to divide up the components into bespoke modules asthey wish, provided that all learning outcomes in eachcomponent are achieved. This rule also assists in theincremental modular award of points by different HEIs,where minimum allocation can vary (i.e. module units of7.5, 10 or 15 credits).

The compulsory component contains learningoutcomes considered essential to being a physicist orengineer working in medicine or biology. The specialistcomponent is where HEI diversification is encouraged,and HEIs can design their own learning outcomes over aminimum of two separate and distinct modules, ensuringthese complying with Blooms/SOLO taxonomy to meetFHEQ Level 7 descriptors. Up to 25 per cent of credits atthe specialist component can be appropriate non-physicsor engineering topics, such as a project managementmodule. The flexibility of this specialist componentfavours innovative new courses in medical physics andbiomedical engineering, and allows for diversification ofthe named degree title (i.e. medical physics and medicalinstrumentation). The project component above is lessflexible and is fixed at 60 UK points, as is the sectorstandard. Additionally, in order to foster communicationskills, a talk and poster activity must be completed by thestudent during their degree to foster communicationskills.

Entry requirementsThis leaves one last component to describe: the entrylevel, which is found below the dotted line. This is anapplicant-specific component of the framework thatenables entry from students with differing, butappropriate, educational backgrounds. Below the dottedline, the modular structure is rigid with no flexibility overmodule design. However, applicants who are able todemonstrate attainment to FHEQ Level 6 for an entrycomponent subject area can be waived the requirement tostudy that entry subject area by an HEI programme leader.So, for example, a physics graduate would be waived theneed to study ‘core physics’ at entry level and indeedother entry subject areas they can show attainment atFHEQ Level 6. Students will, however, still need toacquire 180 points in total to graduate, and cannot transfermore than 30 points from the entry component towardshis/her Masters award. There will be an annual audit ofthis waiver process for each HEI, alongside otherprogramme standards, to ensure consistency across allaccredited courses.

Programmes can apply for accreditation and obtainmore information through the Careers and Trainingsection of the IPEM website (www.ipem.ac.uk) or bycontacting Cathy Brown, Membership and TrainingManager in the IPEM office ([email protected]).Accreditation assessments are currently only available forUK- and Ireland-based HEIs, although the new committeeplans to launch internationally during 2015. The currentcosts of an accreditation assessment are £500 for UK HEIs,with £1,000 for overseas HEIs, plus the refunding of travelexpenses for two assessors during their visit. n

Working group discussionWhilst the authors were involved in frameworkdevelopment from the initial meeting, other expertsmade valuable contributions over the subsequent 18months. Figure 1 shows a working group meeting atHamilton House in September 2013. Careful designconsiderations took up many meeting hours. Firstly, thescheme was named the ‘Masters Level AccreditationFramework’ to be inclusive and future-proof against thegrowing number of Masters degree titles used byuniversities. Of substantially greater workloadimplication was the next decision to redefine thedescriptors of academic standards away from a syllabus-based approach. This was used in the ‘blue book’, wherecourse content is listed in detail for each subject area.Instead, a learning outcome-based approach was adoptedwhere the standard is focussed on describing a minimumstandard that the student should attain in their learningto meet an accreditation standard.

This educational approach matches that of the UK-SPEC (Engineering Council) and the Physics SubjectBenchmark Statements (Quality Assurance Agency).Additionally, the framework learning outcomes map tothese other national educational standards so graduatingstudents have a clear map of their educationalachievement against the requirements for charteredstatus, where further competencies are required throughsubsequent workplace experience. Lastly, thedevelopment of the framework required the splitting ofthe learning outcomes into engineering and physicsstreams, meaning a single programme would beaccredited for either an engineering or a physics route,although the option to comply with both is possible ifHEIs can deliver a broad spectrum of module choices.

The final framework was approved by IPEMProfessional and Standards Council (PSC) in November2013, subject to final revisions. Operations began via anew Masters Accreditation Committee (MAC) that beganaccreditation assessments, through both paperworksubmission and site visits, after Easter 2014.

The frameworkThe Masters framework is shown in figure 2. At firstglance, observe that this framework is multi-level andthat three levels, or components, exist above the ‘dottedline’. This line is important as it defines the boundaries ofundergraduate and postgraduate level descriptors, or ineducational terms, represents the QAA Framework forHigher Education Qualifications (FHEQ) benchmark forLevel 6. To complete a Masters degree, 180 UK creditpoints must be successfully completed by a student, ofwhich 150 must be at FHEQ Level 7 (UK credit points areequal to half a European ECTS point). Thus, students canonly complete 30 UK points from below the dotted line,discussed later, in their accumulation of points to aMasters degree award.

Some rules for figure 2 need explanation. Firstly,students must satisfy all the learning outcomes for eachcomponent of the framework. These learning outcomesare published on the Masters accreditation section of theIPEM website and are divided into the subject area boxesfor each framework level, in some cases with both an

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TECHNOLOGIST NEWS BY FRANCES RYE, DAVID STANGE AND TREVOR WILLIAMS

hree-dimensional conformalradiotherapy (3DCRT), often termedforward planning, is a standard

technique used to treat a variety of cancertypes. In 3DCRT, the dosimetrist mustmodify parameters such as the field size,the relative weight of beam as well as beammodifiers in order to achieve the desireddose distribution.

Over the past 10–15 years, there has beena growing interest in intensity-modulatedradiation therapy (IMRT). Here, radiationfluence from each field is optimised by thetreatment planning software algorithm withthe aid of multileaf collimators (MLC). TheMLCs divide each beam into beamlets. Eachbeamlet can be set to deliver differingintensities of radiation thus allowing forimproved control of homogeneity andconformity across the target and also bettersparing of normal tissue.

Although many treatment sites haveshown benefit from the use of IMRT, othersremain in the realm of 3DCRT. The manualmanipulation of physical beam parameters

needed to achieve one’s goal in 3DCRTcan be time consuming. Once a plan isgenerated that meets all of the necessarycriteria, there is no simple way to ensurethat the plan is fully optimised. Fulloptimisation means that anyimprovement of one criterion has anegative effect on another. This situationis termed Pareto optimality and the set ofPareto optimal plans is called the Paretosurface. An approximation of this isformed by generating multiple plansusing predefined constraints/objectivesset to targets and to organs at risk (OAR).The optimiser minimises dose to a singlestructure, whilst still not compromisingthe plan’s hard constraints. By repeatingthis for each structure and variouscombinations of structures, multiplePareto optimal plans are generated andthus the Pareto surface is formed. Inmulticriteria optimisation (MCO), thedosimetrist is able to navigate this Paretosurface, viewing a range of possible plans,seeing what effect altering a particular

criterion has on the rest of the treatmentplan.

The aim of this study was to show thatMCO, optimised with fluence-based IMRT,but delivered with low segments in aconformal beam arrangement, was able toefficiently produce high-quality 3DCRTtreatment plans.

Ten patients previously planned with3DCRT using XiO treatment planningsystem (TPS) (v4.4; Elekta, Stockholm,Sweden) were replanned with a lowsegment number inverse MCO techniqueusing Raystation TPS (v2.5; RaysearchLaboratories, Stockholm, Sweden). TheMCO plans used the same number ofbeams, dose, fractionation, beam geometryand machine parameters as thecorresponding 3D plans. The MCO-3Dplans did not use any wedged beams andwere limited to 6 MV.

The 3DCRT beams used wedges,multiple beam energies and segmentedfields to aid homogeneity. As only 6 MVbeam energy was supported by the IMRT

T

FIGURE 1. Axial plane dose distribution and DVH comparison of brain case 2. Red arrows highlight areas of dose reduction due to the use of MCO-3D moving dose away from optic apparatus. Figure kindly supplied by David Craft and Fazal Khan, Massachusetts General Hospital, HarvardMedical School, Boston, MA, USA. © F. Khan, D. Craft (2014). 3D conformal planning using low segment multi-criteria IMRT optimization.Available online: arXiv:1401.8196 [physics.med-ph]

3D conformal planning using low segmentmulticriteria IMRT optimisationRADIOTHERAPY PHYSICS

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TECHNOLOGIST NEWS BY FRANCES RYE, DAVID STANGE AND TREVOR WILLIAMS

module on the TPS, the number ofsegments for the MCO-3D plans was slightlyincreased so as to enable fair competitionwith the 3DCRT beams. The Pareto surfacewas navigated, driving OAR doses downuntil target coverage either met that obtainedvia 3DCRT or the minimum target coverage,defined locally, was achieved.

Comparisons were made of the meandoses to organs at risk (OARs), homogeneityindex (HI), monitor units (MUs) and clinicianpreference. A qualitative assessment ofplanning time and plan customisability wasalso made.

MCO-3D plans showed significantreduction in mean dose to organs at risk(OARs) and also used fewer monitor units

whilst maintaining good coverage andhomogeneity of dose within the targetvolume. MCO allowed for easier plancustomisation. Figure 1 shows a typicalexample of the types of organ sparingpossible using MCO with the tabulatedvalues displayed in table 1.

The MCO-3D plans and corresponding3DCRT plan were shown to the clinician andin each instance the MCO-3D was preferred.

The authors concluded that the use ofMCO allowed for the efficient production ofhigh-quality 3D plans. These utilised IMRToptimisation to automatically generate field-in-field type plans, often resulting inreduced mean doses to many OARs. Beingable to navigate the Pareto surface enables

the dosimetrists to view dose trade offs andcreate a superior clinical plan. Adopting thistechnology could streamline treatment planproduction.

‘ CLINICAL TECHNOLOGIST EDITOR COMMENTS:In the UK, radiotherapy centres are being tasked with increasing the amount of IMRT that they deliver to at least 24 per cent of radical patients.

With time pressures being a serious concern, such as those from the Joint Council for Clinical Oncology (JCCO), departments are constantly

looking for ways to reduce the time taken to produce the high quality plans that modern radiotherapy technology allows. IMRT planning is

inherently about the compromise between target coverage and OAR/normal tissue sparing, and it is this iterative trade-off process rather than

computational time involved in the optimisation that can take the most time.

Whilst MCO does not directly affect the speed of the optimisation, its usefulness comes in its ability to help the dosimetrist and physician

rapidly explore trade-offs between competing criteria in a treatment plan. The ability to see the potential effect of dose changes to OARs in real

time during the planning process allows rapid exploration of the Pareto front increasing efficiency during treatment planning, potentially leading

to higher throughput and higher quality plans.

The use of MCO, tested here within the RayStation TPS, is a powerful tool not only for IMRT but also for 3DCRT treatments. I aim to try and put

this through its paces over the coming months and will report back to you with my findings.

If you have a comment on this article, or would like to share your experiences, then please get in touch with me via email:

[email protected]

TABLE 1

ORIG-3D MCO-3D % decrease

HI 0.04 0.06 –50

Brainstem 17.97 14.48 19.4

Chiasm 9.61 3.5 63.6

Left cochlea 3.16 4.56 –44.3

Right cochlea 9.38 2.87 69.4

Right optic nerve 4.58 1.52 66.8

Left optic nerve 1.99 2.5 –25.6

Combined OARs 11.38 9.09 20.1

MU 348 158 54.6

‘ MORE INFORMATIONThis work has been recently submitted to

ASTRO for publication via their journal,

Practical Radiation Oncology and is

awaiting acceptance. However, the article is

available for viewing permanently through

the Cornell University Library website. Khan

F, Craft D. 3D conformal planning using low

segment multi-criteria IMRT optimization.

Massachusetts General Hospital, Harvard

Medical School, Boston, MA, USA; 2014.

[Available online:

http://arxiv.org/abs/1401.8196]

TABLE 1. Dosimetric and monitor unit (MU) comparison of left parietal case. Homogeneity index is reported for the PTV as well as the mean dosesto OARs. Figure kindly supplied by David Craft and Fazal Khan, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. © F.Khan, D. Craft (2014). 3D conformal planning using low segment multi-criteria IMRT optimization. Available online: arXiv:1401.8196[physics.med-ph]

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he AAATE conference (figure 1) bringstogether researchers, professionals,manufacturers, end users and their

families, and combines their knowledge,expertise, needs and expectations, contributingin a multidisciplinary way to create a novelapproach to the advancement of the assistivetechnology (AT) field in Europe.

This 12th European Conference had manyfantastic keynote speakers and parallelsessions which touched on many aspects ofassistive technology. The presentations Iattended were focussed on my main area ofinterest, user perspectives. There were threekey presentations I found very interesting,which I have used to develop practice in myown area of work.

The paper ‘User centred design in practice– developing software with/for people withcognitive and intellectual disabilities’ waspresented by Michael Schaten (TUDortmund University, Germany). Through aformative evaluation the researchers havelearnt that when designing software, thevocabulary and icons used have to be veryclear to the users, as different people learn touse software in different ways. Some peopleuse the pictures, others use text or preferaudio. It was found that the actions

completed by the user on the softwarerequired feedback; this was to show the userwhat the software had done. This was acommon problem experienced by userswhich prohibited them from completing thenext step. The project outcome showed theimportant difference between usability andaccessibility, which the team is using toredesign their software and tests iteratively.

Interviewing young researchersThe paper ‘Young practitioners’ challenges,experiences and strategies in usabilitytesting with older adults’ presented by AnaCorreia de Barros (Fraunhofer PortugalAICOS, Porto, Portugal) shared findingsobtained from semi-structured interviewswith six young practitioners who only hadall of their practical experience with theolder adult population. This presentationexpressed difficulties experienced by youngpractitioners in relation to managing theuser, introducing and conducting theresearch. They found difficulty in managingthe user’s talking, how to interrupt and howto keep to a set appointment time. Thestrategies developed as a result of thisresearch were for the young researchers togain trust through alternative activities

before and after the research, outline goals ofthe time slot in the first few minutes, andposition themselves so that one researcherwas facing the user and the other researcherrotated at an angle. The final finding I foundreally interesting: apparently the positionsthat the researcher sat in relation to the userinfluenced the user’s communication andfocus during the research.

The final paper that I found stimulatingwas ‘Thinking through design andrehabilitation’ presented by Claire Craig(Sheffield Hallam University). Thispresentation talked about how introducingdesign thinking to people with spinal cordinjury as a route treatment improved theparticipants’ independence, resourcefulnessand personal control through beingencouraged to think laterally about theirproblems. This study interested me as it usedoutcome measures that are user specific,which is very close to the type of work Iundertake, and these produced bothquantitative and qualitative outcomes. Thisgave the user confidence to question theirenvironment and gain a toolkit to takeforward in their care.

This conference was well attended andreceived 280 paper submissions from 39

MEETING REPORTS

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ASSOCIATION FOR THE ADVANCEMENT OFASSISTIVE TECHNOLOGY IN EUROPE (AAATE) HANNAH DALTON (Pre-registration Clinical Scientist, Designability – BathInstitute of Medical Engineering)

ALGARVE,PORTUGAL19th–22ndSeptember 2013‘

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ONLINE MEETING REPORTSReports of IPEM meetings are now online only, and together with online copies of thetravel bursary reports can be found at:https://www.ipem.ac.uk/ConferencesEvents/Conferencereportsandabstracts.aspx

‘

ANGELACOTTONScopeMeetingReportsEditor

IPEM meeting reports added since the last issue of Scope went to press include:

The Modern Face of Equipment Management in the NHS (19th November 2013) by Glen Bush. This conference

looked at the options that NHS Trusts have to provide more cost-effective equipment management services

whilst maintaining or improving the quality of the service provision, and featured a wide variety of presentations

from both the public and private sectors.

Flattening Filter Free Photon Beams in Radiotherapy (6th March 2014) by Anisha Boffey. This one-day

meeting brought together the latest scientific and clinical developments in flattening filter free (FFF) beams,

covering both the technical issues around FFF including dosimetric calibration, commissioning and QA, and the

practical issues of how and where FFF modes are useful in clinical practice.

CT Optimisation (8th April 2014) by Fergus Dunn. This meeting discussed the complexities of CT optimisation,

made necessary by the increasing number of CT scans, doses and technological development.

Meetings posted online after the copy deadline for this issue of Scope will also be available to be viewed.


Virtual Phantoms for IGRT QA ImSimQA ™™

OSL-Mkt-ImSim-SCOPE0314-v4

Atlas-based auto-contouring, deformable multi-modality image registration (DIR) and adaptive RTare on the increase.

How can DIR software be tested and validated with limited access to clinical scanners?

ImSimQA is an essential software toolkit thatgenerates ground-truth DICOM test images to validate clinical software systems (OnQ rts®, MIM Maestro™, Velocity, ABAS, SPICE and Smart Segmentation®), and provides quantitative analysis of DIR algorithms.

Save time and close the loop using ImSimQA, the only commercially available standalone

software designed for DIR + RIR QA.

Pukala J, Meeks SL, Staton RJ, et al. A virtual phantom library for the quantification of deformable image registration uncertainties in patients with cancers of the head and neck. Med. Phys. 2013;40:111703. Doi: 10.1118/1.4823467Nie K, Chuang C, Kirby N, et al. Site-specific deformable imaging registration algorithm selection using patient-based simulated deformations. Med. Phys. 2013;40:041911. doi: 10.1118/1.4793723

countries, and 182 papers were accepted fororal presentations and 37 papers for posterpresentations. I submitted an extendedabstract to AAATE 2013, entitled ‘Theimpact of a bespoke engineering referral

service’ which was presented as a posterpresentation. I was honoured to have mypaper accepted for poster presentation. I hada chance to speak to many other researcherswho work in a similar area and we were able

to share our knowledge and experiences.This experience allowed me to draw onknowledge in a wide range of assistivetechnology fields and will now be used inmy work at Designability. n


MEETING REPORTS

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FIGURE 1. The venue, Tivoli Marina Hotel

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experienced Szechuan cuisine first-hand by attending this meeting inChina and it is extraordinary. In some

cases it was too challenging for me; forexample, boiled cow’s stomach or driedjellyfish. In other cases it was delicious andexotic: a glass noodle tomato soup wasdelicate and flavoursome and the kung-pochicken was made with Sichuan pepperswhich contain hydroxy-alpha sanshool, apotassium channel inhibitor which causesa numbing, tingling sensation in themouth. This lasts for about 40 minutes,and added a frisson to the task of chairingthe scientific session which immediatelyfollowed lunch.

About ISCEVThe International Society for ClinicalElectrophysiology of Vision (ISCEV)(www.iscev.org) is an organisation whichaims to promote and extend knowledge,and to promote co-operation andcommunication, amongst workers in thefield. The society issues worldwidestandards for performing visualelectrophysiology tests such as theelectroretinogram, visual evokedpotentials and electro-oculograms and hasan associated journal, DocumentOphthalmologica, published by Springer.

MEETING REPORTS

One of the ways in which the societymeets its aims is by holding an annualSymposium and every third year theSymposium is held in Asia or Australia.In 2010 the membership voted forChongqing as our hosts for 2013.Chongqing is in southwest China and hasa population of around 34 million. That’sthe same as Canada. Its urban areaspreads across 68 kilometres, which is thedistance from Edinburgh to Glasgow. It isenormous. Despite this, it is very strikingwhen the smog lifts thanks to its locationat the junction of the Jialing and Yangtzerivers (figure 1).

In 2012, I was elected as Secretary-General of ISCEV, which involvessubstantial responsibility for managingmany aspects of the society. There areover 300 members of ISCEV from 42countries, comprising ophthalmologistsand scientists. Many of the scientists aremedical physicists or clinical engineersworking in this specialised field of visualelectrophysiology; indeed, the Britishchapter of ISCEV is one of theprofessional bodies supporting thePractitioner and Scientist TrainingProgrammes in Ophthalmic and VisionScience, part of the Modernising ScientificCareers initiative.

The courses and conferenceAs is now customary for ISCEV, theconference is preceded by courses whichlast two days: one on humanelectrophysiology for clinical applicationsand one on animal electrophysiology forbasic scientists. Each course delivers around15 lectures and two workshops supportedby the equipment manufacturers whoexhibit at the conference, and this year bothwere fully subscribed.

The conference attracted almost 200delegates, and oral and poster abstractswere presented in 11 sessions. In addition,there was a standards meeting where theprogramme of reviewing and updating theISCEV standards was discussed and writingcommittees were appointed; there was ameeting of the editorial board of DocumentaOphthalmologica; the ISCEV board meetingwas held to review and plan the activities ofthe society, and the ISCEV membershipmeeting reported activities to themembership and conducted the business ofthe society including elections to boardpositions (figure 2). Despite this fullprogramme, we found time for an excursionto the Dazu rock carvings, a World HeritageSite containing a series of Chinese religioussculptures and carvings dating back as faras the 7th century AD and depicting

FIGURE 1. The skyline of Chongqing, photographed at Nanshan

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INTERNATIONAL SOCIETY FOR CLINICALELECTROPHYSIOLOGY OF VISION SYMPOSIUMRUTH HAMILTON (Paediatric Visual Electrophysiology Service, Department ofClinical Physics & Bioengineering, Royal Hospital for Sick Children, Glasgow)

CHONGQING,CHINA13th–17th October 2013‘

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Buddhist, Confucian and Taoist beliefs. Theastonishing arrays of carvings are around 10metres high and stretch for hundreds ofmetres, containing exquisite, detailedcarvings with both religious and secularthemes. They fortunately survived the anti-religious destruction of the CulturalRevolution.

Origins of electrophysiological signals and genetics of retinal diseaseOne of the key strengths of the clinician–scientist mix which makes up ISCEV is thattheir findings are shared at the same meetingwhich supports rapid cross-fertilisation ofideas. One of the scientific sessions focussedon the origins of electrophysiological signals,largely deduced from animal studies usingpharmacological blockades. This sessionpresented new data about intrinsicallyphotosensitive retinal ganglion cells –relatively newly discovered cells in theretina which behave like rods and cones butwhich control pupil activity and circadianrhythms rather than vision. C.P. Hu’s(Zhenzhou Eye Hospital, Henan, China)paper, ‘ERGs originate in photoreceptors andintrinsically photosensitive retinal ganglioncells’, suggested that these cells contribute tothe electroretinogram at least as much as rodand cone cells, which represents a majorchange in understanding of one of ourstandard tests and was therefore ofsignificant interest to clinicians present.Meanwhile, two papers presented in a moreclinical session described studies of patientswith macular diseases, such as Stargardtdisease, who have their vision spared in themost central area of their retina. Both talks

highlighted the incomplete genetic picture ofthese conditions, thereby returning usefulinformation to the scientists; in this case,geneticists (Kaoru Fujinami, UniversityCollege London, ‘Clinical and molecularanalysis of Stargardt disease with preservedfoveal structure and function’; S. Goto,Osaka University, Osaka, Japan, ‘Clinicaland molecular analysis of maculardystrophy with preserved foveal structureand function’).

All abstracts are available to access onlinewithout subscription at http://link.springer.com/article/10.1007/s10633-013-9410-1.

Medical physicists and clinical engineers at ISCEVThe role of MPCE in visualelectrophysiology was highlighted in Scope’sDecember 2013 issue in the article ‘Biosignalprocessing and classification: a comparisonof techniques’, where Richard Hagan, anISCEV member, provided expert comments.During the 2013 ISCEV Symposium, thepapers listed below were examples ofresearch where the lead or key author was aphysicist or engineer:n Multifocal pattern ERG: local differencesin P50 vs N95 (Michael Bach, University ofFreiburg, Germany)n Comparison of dark-adapted ERGs tostandard and bright flashes in controls andpatients (Chris Hogg, Moorfields EyeHospital, London)n Skewness of the distribution of normalERG values and implications for calculationof the normal range (Michael Lee, MonashUniversity, Australia)n Time–frequency domain analysis of thephotopic hill reveals new and diagnostically

relevant features of the human photopic ERG(Mathieu Gauvin, McGill University &Montreal Children’s Hospital, Canada)n The rise-time of the dark-adapted a-wave:a simple measure of rod sensitivity (JohnRobson, University of Houston College ofOptometry, USA)n The subretinal implant alpha IMS todeliver useful vision in photoreceptordisease (Eberhart Zrenner, University ofTuebingen, Germany)n Sensitivity and specificity of mfERG inscreening for hydroxychloroquine/chloroquine induced retinopathy (StuartCoupland, University of Ottawa EyeInstitute, Canada)n Vision in 6-month-old infants born todrug-misusing mothers prescribedmethadone in pregnancy (Ruth Hamilton).

The futureZheng Qin Yin and her team organised aSymposium which was remarkable for thequality of the science and the efficient andfriendly management of the event. ISCEV’snext Symposium will be in Boston in 2014and planning is already well underway.Attendance is usually higher when theSymposium is in the Americas, so weanticipate a busy and high-qualitySymposium. Advances in technology andgenetics will continue to change the way wedo and use our electrophysiology tests, andthe board continually addresses our need tomove with the changing healthcarelandscape.

May I take this opportunity to thankIPEM for the travel bursary which supportedmy attendance at ISCEV’s 51st meeting inChongqing. n

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FIGURE 2. Ruth Hamilton (right) and Society President, Professor Patrizia Tormene, chairing the membership meeting


MEETING REPORTS

he Institute of Electrical andElectronics Engineers (IEEE) MedicalImaging Conference (MIC) took place

between 27th October and 2nd November2013 in the great city of Seoul (Republic ofKorea). It was the first time that the MICtook place in Asia-Oceania and coincidingwith this, the Nuclear Science Symposium(NSS) and Room-temperatureSemiconductor X-ray and Gamma-rayDetectors (RTSD) conferences also tookplace. According to the data provided bythe organisers, approximately 2,400 peopleattended with 3.3 per cent coming from theUnited Kingdom. 1,679 abstracts werepresented from 1,846 submissions. Of these,691 presentations were in the MICconference. Seoul is an exciting city, full ofhistory and culture as well as impressivemodern architecture. Seoul sits among themountains with the River Han dividing thecity into north and south. The conferencetook place in the modern and enormousconvention centre COEX (figure 1), situatedin the financial district of Seoul calledGangnam (which literally means ‘South ofHan River’).

As for the conference, MIC is the leadinginternational meeting on the physics,engineering and mathematical aspects ofnuclear medical imaging. In recentdevelopments, multimodality approacheshave become more important and thecontent of MIC has been increasing. Some ofthe fields covered in this conference were:n emission tomography instrumentation(PET, SPECT);

n medical imaging technologies such as CTand MR;n multimodality systems;n high resolution and pre-clinical imaginginstrumentation;n image reconstruction methods, andn data corrections and quantitative imagingtechniques.

The oral presentations and postersessions were well organised into differenttopic groups with world leaders attendingand presenting. Posters sessions enabledgood direct interaction with author(s),allowing the exchange of ideas andnetworking potential. The conference alsooffered short courses (at additional cost) andrefresher sessions (included in theconference price) on various topics. Someexamples of short courses offered this yearwere: ‘Radiation detection andmeasurement’, ‘Medical imagereconstruction’ and ‘Physics and design ofdetectors for SPECT and PET’. Anothercourse offered was ‘Geant4 simulation(Monte Carlo) toolkit’, which I attended.This course was very interesting but moredirected towards physicists and engineersworking in the field of high-energyparticles. However, it was a good

introduction to Monte Carlo modelling withthe Geant4 tool. The courses were taught bylecturers who are leaders in their field andcourse material is provided to participants.

There were various workshopsthroughout the conference and the numberof these has increased since I last attendedthis conference in 2010 (Knoxville, USA).Some of the workshops that took placeduring the conference were: ‘Newtechnologies in hadron therapy: particleimaging and optimisation of treatmentdelivery’, ‘PET-MR’ , ‘SPECT-MR’,‘Quantitative four-dimensional imagereconstruction methods’ and ‘Intraoperativeand intratherapy molecular imaging’.Various users’ meetings occurred during theconference; for example, a STIR users’meeting and a GATE users’ meeting (MonteCarlo simulation tool based on Geant4 forPET, SPECT CT, optical imaging andradiation therapy) and others that wereextra to the official agenda of theconference.

The next MIC conference will be held inSeattle (USA) from 8th–15th November2014. IEEE offers student travel grants toassist with travel costs and, as per myexperience, travel grants may also beavailable from the IPEM. Furtherinformation on MIC meetings can be foundon their webpage: http://www.nss-mic.org.It is expected that for each abstract, aconference proceeding (non-peer reviewed)is created to describe the work, methodsand results in a journal-type document.Alternatively, a submission to Transactions

IEEE MEDICAL IMAGING CONFERENCE ANDVISIT TO NEUROSCIENCE INCHEON CENTREJOSE M. ANTON-RODRIGUEZ (Wolfson Molecular Imaging Centre, University ofManchester and The Christie Hospital)

SEOUL, KOREA27th October–2ndNovember 2013‘

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Seoul sits amongthe mountains with

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MEETING REPORTS

on Nuclear Science can be made. This is anIEEE journal which is peer reviewed. Theseconference proceedings are available onlineafter the conference on the IEEE Xplorewebsite and this work can be referenced insubsequent publications.

In summary, the annual IEEE MIC-NSS-RTSD conference, together with theinteresting number of workshops, coursesand users’ meetings that take place duringthe conference, always has something tooffer to participants. The level of the talksand poster presentations is sometimesoverwhelming, since the concepts and thetechnicality of what is presented might notbe easily understood, but the materialpresented in this conference tends to beavailable online afterwards so it can befurther revised (depending on the authorpreferences, sometimes the author will aimto publish in peer-review journals what wassubmitted to the conference).

The institution where I am based andcurrently performing a part-time PhD is theWolfson Molecular Imaging Centre (WMIC)at the University of Manchester, with linksto The Christie Hospital. At this institutionthere is one of the few dedicated brainscanners that have the highest spatialresolution for human imaging, the high-resolution research tomograph (HRRT). TheHRRT is capable of achieving a spatialresolution of 2–3 mm, due to its smalldetector crystal size of 2.2 mm and a doublescintillator crystal layer Phoswich detector.This provides some discrete level of depthof interaction DOI (minimises the

misplacement of lines of response (LORs)due to parallax errors). Resolution canfurther be improved by resolutionmodelling (RM) in image reconstruction.RM in brain imaging is one of my areas ofinterest and where I presented work at theconference with two poster presentations,one as the main author and another as asecondary author.

Selection of interesting topics discussed at MICAt the moment there are no clear indicationson whether manufacturers will includehardware features such as the HRRT’s DOIin future scanner models. The main clinicaluse of PET at the moment is in oncology forwhole body applications, which arguablydoes not require the same level of spatialresolution as brain imaging. This is due tothe limitations that internal body motionplaces on the achievable spatial resolution.Respiratory motion in PET imaging is aproblem since physiological motion of 6–18mm is expected on scanners with spatialresolution of the order of 5–6 mm. On howto correct for internal body motion andelastic motion were a series of presentationswhich I found very interesting. For example,two presentations were given by Inki Hong(Siemens Healthcare USA, Knoxville, USA)entitled ‘The strategies on elastic motioncorrections’ and ‘The elastic motioncorrection for cardiac PET studies’. Dr Hongintroduced the three main ingredients of amotion correction strategy. First, a correctmeans to gate data (respiratory cycles or

cardiac cycles) is necessary so that thevectors to define the elastic motion can beextracted accurately. For gating, ECG,external motion tracking systems likemotion belt, PET data-driven methods oreven the possibility of using MR on the newMR-PET scanners can be used. The secondingredient to correct for motion is thatinformation on motion needs to beextracted. In Dr Hong’s work, elastic motioninformation is extracted using masspreservation optical flow (MPOF) from PETdata. MPOF produces fully 3D optical flow,does not require a priori segmentation of theorgans and does not use cross-modalityinformation (e.g. MR or CT with addeddose). The third step is the motioncorrection, which in his case is performedduring the iterative reconstruction. MPOFcan be integrated into the reconstructionprocess, in both the forward and thebackward projection in what he referred toas elastic motion correction (EMC)algorithms.

Normally, image reconstruction withmotion correction is performed throughsumming gated images in a commonreference frame. The combination ofprocessed data with poor statistics(individual gates) can result in high imagenoise and bias in the final image. Insummary, Dr Hong showed images that,when combining accurate gating MPOF andEMC, successfully corrected for cardiac andrespiratory motion, improving resolutionand reducing noise compared to staticimages (no motion correction) and gated

FIGURE 1. Logo of IEEE NSS/MIC/RTSD 2013 in Seoul (top left) and apicture (top right) of one of the entrances to the COEX centre where theconference was held. The main hall of the conference during a breakbetween sessions (botton left) and Gwanghwamun Gate to theGyeongbokgung Palace in Seoul (bottom right)

FIGURE 2. (Top) The entrance to Neuroscience Research Institute atGachon University. Scanners at this facility: the PET HRRT scanner witha unique transparent cover (bottom left), the rail system to connect thebed between scanner rooms (bottom middle) and a picture of the MRI7T (bottom right) with the head coil used for imaging which is placed inan adequate MRI shielded room (inset)

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MEETING REPORTS

images for cardiac and lung imaging. On thesame subject, work presented byCharalampos Tsoumpas (University ofLeeds and Kings College London) entitled‘4D reconstruction for correction ofrespiratory and bulk motion in PET-MR’showed how MR information can be used toassess bulk motion (patient displacementand rotation) or to describe respiratorymodels with different gates and incorporatemotion information into the reconstructionprocess itself. In the case of Dr Tsoumpas’group, the reconstruction processincorporates regularised motion-compensated reconstruction.1 The code isaccessible on Software for TomographicImage Reconstruction (STIR,http://stir.sf.net).

Limitations and solutionsReaders might be aware of some of thelimitations of MR on measuring attenuation,which in some cases might not be accurateand may lead to artefacts on thereconstructed images. These limitations andpotential solutions were the subject ofdifferent abstracts presented in theconference. For example, in a presentationby Harold Rothfuss (Siemens HealthcareUSA, Knoxville, USA), work on how toperform transmission scans using thebackground radiation of the scintillationcrystals LSO with PET and TOF wasintroduced. In brief, the scintillation crystalcontains the radioactive isotope 176Lu (2.6 percent abundant in naturally occurringlutetium). The decay scheme of 176Lu is

through beta decay with coincident cascadegammas with energies of 307, 202 and 88keV. Some alterations are needed in thescanner in order to be able to detect thecoincidence signal of 176Lu. The first is toincrease the TOF coincidence window toallow a coincidence radius bigger than thephysical radius of the scanner. Otheralterations are added to be able to detect thebeta decay ionising radiation in the crystalby reducing the constant fractiondiscrimination (CDF) of the detectors andto detect the gammas from 176Lu (addingadditional energy windows centred on 307and 202 keV). The transmission signal from176Lu is achieved by recording the betaionising energy on the crystal in theoriginating detector and one of the 307 and202 keV photons detected within thetransmission TOF window in the oppositedetector. The transmission signal iscompared to a 176Lu blank scan (no patientor bed in the FOV) to create the attenuationmap of the FOV. The presentation showedthe feasibility of using this method toobtain the attenuation properties and howfor some cases the transmission dataacquired with 10 minute scans was enoughto perform PET image reconstruction(mainly head scans). The presentationshowed work in progress being carried out,since the attenuation information obtainedwas noisy and could lead to errors;however, the transmission data acquiredwith 176Lu could be used as priors for MR-based attenuation reconstructions or innovel reconstruction approaches which are

starting to be implemented and presentedin the literature (and also present in thisMIC) that estimate the attenuation andemission simultaneously from PET TOFdata without the need of transmissionscans such as MLACF.2

Detectors in PET and SPECT were alsowell covered in this conference, wherefrom year to year new developments areshown by different groups. It wasinteresting to see recent advances in digitalsilicon photomultipliers (D-SiPMs) andhow these detectors can perform in termsof detection efficiency, time resolutionallowing better TOF performance, spatialresolution, cost reduction and the fact thatthese planar solid-state devices areinsensitive to magnetic fields and requirelow bias voltage. With these properties itseems that future generations of PETscanners might not includephotomultipliers and, as announced in theconference by a main PET manufacturer, anew generation of PET/MR scanners willsoon start to become available on themarket using SiPMs instead of avalanchephoto diodes (APD).

Neuroscience Research Institute atGachon University, Incheon-SeoulDuring the conference another users’meeting took place in an area I havecollaborated extensively on during the past6 years – the HRRT community users’meeting. The HRRT community consists ofaround 14 centres including universityhospitals or other research centres like the

FIGURE 3. High-resolution MRI T2* weighted sagittal image of thebrainstem area taken with 7T MRI (left) and the same MRI image fusedwith an FDG PET image obtained with HRRT (right) (courtesy ofNeuroscience Research Institute, Gachon University of Medicine)

FIGURE 4. Convertible high-resolution PET scanner (left) and picture ofa poster (right) explaining different features of this scanner which isunder development at the moment at the Neuroscience ResearchInstitute, Gachon University

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MEETING REPORTS


WMIC which have a HRRT scanner. Thisyear’s HRRT users’ meeting was veryspecial as it took place in the NeuroscienceResearch Institute at Gachon University inIncheon-Seoul. Our hosts were ProfessorCho Zang-Hee and Dr Young Don Son,who together with their colleaguesprovided the HRRT users with a great tourof the facilities, delivered a series of veryinteresting presentations on the researchactivities of this centre and invited us toenjoy delightful typical Korean food in abeautiful restaurant close to the researchinstitution. This department has a uniqueconfiguration of scanners; aside fromhaving an HRRT for state-of-the-art PETbrain imaging, the centre has a brain 7TMRI scanner for high-resolution anatomicalimaging which is also used for fMRI. Thescanner’s configuration is in sequence sothat the patient can be moved from onescanner to the other with a bed systemsitting on a rail (shuttle bed system). A fewimages of this configuration are shown infigure 2. During the tour we were shown

different examples of the great detail ofanatomic features of the brain that can beseen with this 7T MRI. An example can beseen in figure 3, where a representativePET/MRI fusion image of the brainstem isshown, with a T2* weighted MRI sagittalimage (figure 3 left) showing a variety ofstructures of the area imaged. If fused withfunctional FDG images from the HRRT(figure 3 right) it provides a uniqueopportunity to study anatomically andfunctionally small nuclei in the brain.

Another interesting instrumentationdevelopment in this centre is a high-resolution PET system with detectors 4.05 ×4.5 × 20 mm LYSO crystals with opticalcoupling with SiPM. This scanner couldeither be adequate for brain or whole-bodyimaging by expanding or contracting theblocks containing the scanner detectors,therefore changing the diameter of thegantry bore (figure 4). The gantry designalso permits fine and precise lateral motion(wobbling concept) to oversample theobject and obtain in brain imaging mode

high-resolution brain images of resolutionsbelow 2 mm FWHM.

I would like to thank the IPEM, TheChristie Hospital, University of Manchesterand my PhD supervisors for all the helpand support in enabling me to attend theMIC IEEE conference 2013. n

REFERENCES

1 Tsoumpas C, Polycarpou I, ThielemansK, Buerger C, King AP, Schaeffter T,Marsden PK. The effect ofregularization in motion compensatedPET image reconstruction: a realisticnumerical 4D simulation study. PhysMed Biol 2013; 58: 1759.

2 Nuyts J, Rezaei A, Defrise M. ML-reconstruction for TOF-PET withsimultaneous estimation of theattenuation factors. Nuclear ScienceSymposium and Medical ImagingConference (NSS/MIC), IEEE; 2012:2147–9.

ptical imaging is not yet anestablished field in medicalengineering and physics, and many

clinical scientists and technologists may notbe familiar with it. This is especially true forengineering trainees on the STP scheme, forwhom there is no longer the scope to getmuch experience with imaging. However,as an STP trainee choosing to specialise indevice development, I found myselfspending a large part of my specialistplacement completing a project related tooptical imaging of skin cancer, based in thenon-ionising radiation section of medicalphysics at St Thomas’ Hospital, London.The aim of my project was to develop andvalidate a tracking system to enablemapping the margins of skin cancer lesionsusing an optical imaging modality calledoptical coherence tomography (OCT). Thismodality uses a harmless infrared laser toimage up to 1 mm below the surface of skin,with microscopic resolution. OCT isanalogous to ultrasound imaging, andproduces real-time b-mode images in whichfeatures of skin cancer can be distinguished.

My supervisor and I submitted anabstract on my project work to the annualSPIE Photonics West conference, and werefortunate to have it accepted as an oralpresentation. I therefore had theopportunity to attend the conference, heldat the Moscone Center (figure 1) in SanFrancisco from Saturday 1st to Thursday 6thFebruary 2014.

SPIE (the international society for opticsand photonics) is a non-profit internationalsociety, dedicated to the advancement ofoptical and photonic technologies.Photonics West is SPIE’s largestinternational conference, which this yearhad over 21,000 attendees, 4,600 oralscientific presentations, 2,000 posterpresentations and an exhibition with 1,260companies (figure 2). Photonics Westincorporates four sub-conferences,including BiOS, the world’s largestbiomedical optics conference. Within BiOS,my paper was accepted as part of theAdvanced Biomedical and ClinicalDiagnostic and Surgical Guidance SystemsXII sub-conference.

With over 20 parallel sessions on mostdays, and presentation rooms as far as 10minutes’ walk from each other, it was adaunting task to plan the week. However, Imanaged to track down many interestingtalks, and some of the highlights aresummarised below.

BiOS Hot TopicsDespite an 8-hour jet lag, I managed to stayawake long enough to attend the popularBiOS Hot Topics plenary session on theSaturday evening. Many of the leadingresearchers in biomedical optics gave talks,including Lihong Wang (WashingtonUniversity, St Louis, USA), who describedrecent achievements in photoacousticimaging. This relatively new imagingmodality circumvents the diffusion anddiffraction (and thus depth) limitations ofoptical microscopy, by detecting thebackscattered acoustic waves generated bylaser–tissue interactions. In only the pastdecade, photoacoustic imaging has risen toshow immense promise, producing imagesof microscopic resolution at depths of up

SPIE PHOTONICS WEST 2014: LASER,PHOTONICS, BIOMEDICAL OPTICSMEGAN DUFFY (Clinical Scientist Trainee, King’s College Hospital/Guy’s & StThomas’ NHS Foundation Trust, London)

SAN FRANCISCO,USA1st–6th February2014 ‘

O

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to a few millimetres, far deeper thancurrent optical technologies can probe, aswell as images of ultrasonic resolution atdepths of up to 10 cm. It has also been usedto produce functional images which rivalMRI, but with the low cost and convenienceof a portable imaging probe. Photoacoustictechnology has potential applications infunctional brain imaging, label-free in vivocell analysis and image-guided biopsy,amongst others.

Figure 3 shows two images from ProfessorWang’s presentation, taken from his paperpublished in Science: (a) an optical resolutionphotoacoustic microscopy image of the bloodvessels in a mouse ear; (b) a photoacousticcomputed tomography image of cerebralhaemodynamic changes in response to one-sided whisker stimulation in a rat.

Eric Swanson (editor of the weeklyresearch roundup OCT News) spoke on thechallenges involved in clinical translation ofnew OCT devices. He emphasised theimportance of patience and perseverance,both on the part of developers and investors,as each of the stages involved (development,meeting regulatory requirements, initial salesand iterations, market growth and, finally,the next generation of a product) can take3–5 years. He also highlighted theimportance of government sponsorship ofemerging medical technologies. Of theroughly 40 OCT systems companiesworldwide, 42 per cent benefited fromgovernment funding at some stage.

Photonics in Dermatology and PlasticSurgeryThis sub-conference on dermatologicalapplications of optics was of particularrelevance to my work. The keynotepresentation on Sunday morning was givenby Rox Anderson (Wellman Centre forPhotomedicine, Massachusetts GeneralHospital, Boston, USA), a dermatologyclinician and researcher who has become achampion of optical treatments for skindisorders.

He emphasised a problem-drivenapproach, and therefore began the talk byoutlining the myriad dermatologicalconditions which could benefit fromadvances in optical diagnostics ortreatments. These ranged from skin cancers,to burn and scar tissue damage, toconditions such as acne. In particular, hestressed that treatment for skin cancers wasstuck in a rut, with surgical excision andtopical medicines being the predominantapproaches, whilst optical treatments havebeen largely unexplored. This is despiteadvances in laser treatments in other, non-clinical, areas of dermatology, such as hairand tattoo removal. He hopes that rapid,scarless laser treatments for many types ofskin cancer will soon become a reality, anddescribed one possible method calledfractional laser treatment. This method usesan array of variable-depth micro-cuts toremove epidermal tissue with nopermanent scarring.

He then described his work usingfractional blistering to treat radiation burnsof children in Southeast Asia. This involvesa device called the CelluTome EpidermalHarvesting System, which combines heatand negative pressure to painlessly harvestan array of 128 2-mm-diameter blistersfrom a healthy skin site, removing only theepidermis to prevent scarring. This array ofblisters is then grafted on to the burns,enormously improving their appearance.The images of skin treated using thisprocedure induced audible gasps from theaudience. Unlike in conventional skingrafts, the donor site (which is usually onthe inner thigh) heals in 3–4 days, and canthen be harvested again.

The optical imaging in dermatologygroup from Memorial Sloan-KetteringCancer Center in New York dominated thereflectance confocal microscopy (RCM)session on Saturday afternoon. RCM isanother optical imaging modality, whichhas a reduced penetration depth comparedto OCT but has superior resolution,producing in vivo images of skin which arecomparable to histology.

Milind Rajadhyaksha (Memorial Sloan-Kettering Cancer Center) gave an overviewof confocal microscopy of skin cancers,including his vision for the technology,which includes rapid, non-invasive skincancer diagnosis and intra-operativeimaging to confirm complete removal ofcancers. He also explored the current


MEETING REPORTS

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FIGURE 1. The Moscone Center FIGURE 2. The exhibition hall

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challenges, such as the small field-of-viewof handheld imaging probes, difficulty ininterpretation of images by inexperiencedclinicians, and the limited penetrationdepth. He finished by emphasising theimportance of clinical champions, withoutwhom any new medical technology willstruggle to get off the ground.

Kivanc Kose (Memorial Sloan-Kettering Cancer Center) gave twointeresting talks on his work. He has beeninvolved in developing algorithms forautomatic detection of features of interestin RCM images. Such features includestratum corneum thickness and thelocation of the dermal–epidermal junction,at which depth many cancers are found.

Eileen Flores (Memorial Sloan-KetteringCancer Center) concluded the session byoutlining a recent feasibility study intointra-operative imaging using a handheldRCM probe, which had a positive outcome.The major challenges faced during thisstudy included ensuring adequate infectioncontrol whilst also maintaining imagequality, as well as developing an efficientimaging protocol.

Prolific researcher Daniel Gareau (TheRockefeller University, New York, USA)presented a total of five papers and oneposter during the conference. Oneparticularly interesting talk was entitled‘Hyperspectral imaging for melanomascreening’. This described a new systemdeveloped by his group, which images a

MEETING REPORTS

region of skin containing a suspectedmelanoma lesion at a series of differentwavelengths, in order to measure thespectral content of the lesion at differentdepths. It then analyses this data using aspecially developed algorithm to producea risk score for the lesion. This system hasa higher sensitivity and specificity than thebest commercial alternative, and thereforehas the potential to improve the earlydetection of melanoma, with minimal costimplications.

My presentation I delivered a 20-minute presentationentitled ‘Motion tracking to enable pre-surgical margin mapping of basal cellcarcinoma using optical imagingmodalities: initial feasibility study usingoptical coherence tomography’. In thispresentation I described the system I haddeveloped to enable mapping the marginsof basal cell carcinoma skin cancer, whichoften infiltrates beyond the visible lesionon the surface of the skin. The systemcombined an electromagnetic motion-tracking module with a commercial OCTsystem. In this way, the position of thehandheld imaging probe could be mappedin space, and thus the position of thecancer appearing at the focus of the probecould be calculated. The system included acustom software interface, to allow aclinician to plot the location of pointscorresponding to the subdermal cancer

border, as viewed in the OCT images,onto a clinical photograph of a lesion inreal time. I then discussed the results ofboth bench and clinical validation. Thepresentation seemed to be well received,and I received some useful feedback frommembers of the audience.

I would like to thank IPEM forsupporting my attendance at PhotonicsWest, by covering the majority of the costof flights, registration fees andaccommodation.

As a trainee with no previousexperience of a major internationalconference, the trip was extremelyvaluable. I had the chance to present mywork to biomedical optics experts, whichwas a boost to my confidence as aresearcher. I came away with a freshperspective on the field, and several ideaswhich may help to inform future skinimaging research at St Thomas’ hospital.It was also a great opportunity tonetwork, in particular to strengthen myties with the Optical Imaging inDermatology group at Memorial Sloan-Kettering Cancer Center, with whom Ispent part of my elective training period.

I stayed on for an extra day after theconference to do some sightseeing andmake the most of the 10-hour flight.Highlights included riding a cable car upSan Francisco’s famous hills and a walk tothe marina with views over the GoldenGate bridge. n

FIGURE 3. Photoacoustic images from Professor Wang’s talk. (a) Optical resolution photoacoustic microscopy image of the blood vessels in a mouse

ear, coloured according to their oxygen saturation (sO2). (b) A photoacoustic computed tomography image of cerebral haemodynamic changes,

Δ[haemoglobin], in response to one-sided whisker stimulation in a rat. Both images taken from Wang L, Hu S. Science 2012; 335: 1458

ba


elcome to the second

issue of Scope ‘Book

Reviews’ 2014. There are

seven book reviews in this

issue. Textbook reviews

cover the medical physics and popular

science genres (see table 1).

There are a number of new textbooks in

the ‘Just Published!’ section, including

Clinical Engineering, which provides a

broad reference to the core elements of

the subject; Smashing Physics, which

gives an insider account of the work at the

Large Hadron Collider at CERN and the

reality of life in an underground bunker,

and Pattern Recognition and Signal

Analysis in Medical Imaging, which looks

at the theory and applications of neural

networks and fuzzy logic.

You will find useful ‘New Reports’, such

as ‘Scaling the Heights: An Overview of

Higher Specialist Scientific Training

(HSST) in Healthcare Science’, ‘European

Guidelines on Medical Physics Expert

(MPE)’ and, for readers working in

radiotherapy, ‘Vision for Radiotherapy

2014–2024’, which covers topics such as

challenges (e.g. capacity) and financial

constraints, access to innovative

technology, staffing and workforce; there

is also the ‘Safer Radiotherapy’

newsletter, detailing error data analysis.

Readers interested in reviewing should

get in touch with me so I can arrange to

send you the required material directly

from the publisher. Remember, reviewing

counts towards your CPD – a requirement

for those registered with the HCPC.

If you have any thoughts on this or any

other section of Scope (e.g. improvements,

other sources of reports and books,

general aspects) then please get in touch

with me. Your feedback will help shape

this magazine into a form that will benefit

the entire medical physics and clinical

biomedical engineering community.

Usman I. Lula is a Principal Clinical

Scientist based in the Radiotherapy

Planning section (Radiotherapy Physics

QEMC) at the Queen Elizabeth Hospital,

University Hospitals Birmingham NHS

Foundation Trust, UK.

Email: [email protected]

BOOK REVIEWS

INTRO

WSPECT – Technology,Procedures andApplications

This is anattractivelypresented overviewof recentdevelopments inclinical SPECT,aimed at a generalclinical audience.

The book startswith brief reviews

of the physics of SPECT, and SPECT forinternal dosimetry. However, the bulk ofthe book is a series of reviews on differentclinical uses of SPECT, includinghyperparathyroidism, bones and lungs,with three chapters each on the topics oftumour imaging, cardiac imaging andneuroimaging.

The chapter on primaryhyperparathyroidism emphasises theneed for other imaging to identify thyroidpathology which could otherwise bemistaken as parathyroid nodules. Thechapter on malignant bone diseaseidentifies the advantages of SPECT andSPECT/CT in classifying indeterminatelesions from planar bone scans. In mostcases routine whole-body SPECT is notfelt to be viable, but where oseolyticlesions are likely, such as in multiplemyeloma, it should be used.

A useful review of ventilation/perfusion SPECT follows, which explainsthe advantages of SPECT over CTPA,including radiation dose, arguing thatbased on the evidence SPECT should bethe principal test. I think this is one ofthose arguments which is decided moreon local clinical preference andavailability than anything else, but still it

has been heartening to see theresurgence of nuclear imaging in thisarea in recent years.

The following two chapters onneuroendocrine tumour imaging givegood coverage of a very complicatedarea, showing that considerableunderstanding of the underlyingphysiology is required to fullyinterpret the different images.

The cardiac section comprises aconcise review of recent advances, alonger chapter reviewing imaging atdifferent stages in myocardialinfarction, including tracers onlyavailable in research centres, and apractical chapter about I-123 cardiacSPECT. The final three chapters onneuroSPECT cover Parkinson’sdisease, epilepsy and brain tumourevaluation. The first two are usefuloverviews, but the third seemssomewhat outdated as many of thereferences come from the 1990s, and itis not made clear what is still relevantin the age of PET/CT.

Overall, I have mixed feelings aboutthis book. Coverage is uneven, withsome chapters being very practical,others reviewing the researchliterature, and some overlap. It feelsunder-edited, with no introduction sono obvious reason for inclusion orexclusion of subjects, and as aconsequence lacks personality.However, it is largely well written and

TABLE 1

Book title Reviewer

n SPECT – Technology, Procedures and Applicationsn Quantifying Morphology and Physiology of the Human Body Using MRIn The Gamma Camera – A Comprehensive Guiden Bio-Tribocorrosion in Biomaterials and Medical Implantsn Medical Imaging – Technology and Applicationsn 4D Modelling and Estimation of Respiratory Motion for Radiation Therapyn Hadron Therapy Physics and Simulations

David HallLukasz PribaElizabeth HowellJulian MinnsElizabeth BerryMark WorrallStuart Green

The bulk of the bookis a series of reviews

on different clinical usesof SPECT

““


Reviews of textbooks published onmedical physics, along with recently

published books and new reports

quantifying properties other than thepresence of protons or other observableMRI nuclei, such as tissue elasticity,conductivity and permittivity andsusceptibility mapping. Each chapterbegins with discussions of the physicsbehind the relevant imaging techniqueand provides comprehensive informationabout key requirements for imageacquisition, processing and analysis.Some sections also briefly introducerelevant software packages used forimage processing, analysis and modellingof data. Then, various clinicalapplications are presented. Tabulatedsummaries of key data from relevantstudies, such as reported ADC values fortissues and tumours, is provided, as wellas an extensive list of references for eachof the chapters.

The book makes a good use ofdiagrams, figures and clinical images tohelp explain the principles described.Thirty-two figures are reproduced incolour in an insert located in the middleof the book. Unfortunately, the figures inthe insert are scaled down, whichsometimes makes it difficult to see thedetails in the images. Providing a biggerversion of these in colour would be morebeneficial to the reader. Alternatively,colour figures can be downloaded fromthe publisher’s website.

Overall, this book acts as a goodreference manual for researchers,clinicians and scientists who would liketo use these novel techniques in theirpractice. It is a self-contained and well-detailed summary of available techniquesin quantitative MRI. Regardless of itshigh price, it would be a good purchasefor any medical physics department thathas involvement in clinical MRI as atraining and study resource.

Mr Łukasz Priba is a Pre-registrationClinical Scientist in MRI and DiagnosticRadiology (Medical Physics Department) atthe Ninewells Hospital and Medical School,NHS Tayside, Dundee, UK

QUANTIFYING MORPHOLOGY ANDPHYSIOLOGY OF THE HUMAN BODY USINGMRIL. TUGAN MUFTULERPublisher: Taylor & Francis / CRC Press ISBN: 978-1-4398-5265-1Format: HardbackPages: 525Price: £108.00

illustrated, and presents a good overviewof many aspects of SPECT, so would be auseful reference.

Dr David Hall is Head of the NuclearMedicine Physics Section, Department ofMedical Physics and Bioengineering at theUniversity Hospitals Bristol NHSFoundation Trust, Bristol, UK

SPECT – TECHNOLOGY, PROCEDURES ANDAPPLICATIONSHOJJAT AHMADZADEHFAR, ELHAM HABIBI(editors)Publisher: Nova Science Publishers, New YorkFormat: Hardback ISBN-13: 978-1-62808-344-6Pages: 261Price (publisher's website): £125

QuantifyingMorphology andPhysiology of theHuman Body UsingMRI

Currently, there is agrowing interestwithin the MRIcommunity fordevelopingquantitative MRIapplications. Manyrecent internationalscientific meetingsplaced great

emphasis on these topics and MRI systemmanufacturers have started to includenew data acquisition techniques andsoftware interfaces for processing andanalysis. The authors recognise thisconsiderable interest, and address theneed for a comprehensive body ofknowledge for the scientific community.This book is one of the newest additionsto the ‘Series in Medical Physics andBioengineering’ by Taylor & Francis/CRC Press. It is a well-written hardbackaiming at delivering the latest scientificapproaches to a broad range ofquantitative methods in clinical MRI.

The book is split into two parts: brainand body (the latter focussing oncartilage, musculoskeletal, cardiovascularand cancer). The last three chapters focuson new and upcoming techniques for

The Gamma Camera– A ComprehensiveGuide

In titling his bookRichard Lawsonhas clearly takeninspiration fromthe old Ronsealadverts; the contentis very much whatit says on the cover.

The bookdescribes itself as

targetted primarily at trainee physicistsand in both style and content it is wellmatched to this readership, although theclarity brought to bear on the finerdetails of the subject makes it aninteresting read for the qualifiedphysicist too. The level of detail andunashamedly scientific and technicalperspective may put off the non-specialist, but it shouldn’t proveinaccessible to anyone willing to stickwith it.

The book is structured logically, withlater chapters building on foundationslaid earlier. A thorough index anddetailed sub-sectioning makes itamenable to a certain amount of use as areference text, but this is clearly not itsprimary purpose. The writing style ismuch like having an experienced, patientcolleague taking you through something;modern textbook devices such assummary boxes or self-assessmentquizzes are eschewed in favour of astraightforward sequential ‘laying down’of the information. The book isextensively illustrated with a goodnumber of well-chosen photographs anddiagrams that add interest and clarity.

The author makes no apology for theinclusion of topics that are notnecessarily relevant to modern gammacameras and in my opinion no apology isneeded; the influence of older cameras iswrit large in much of our terminologyand techniques and for youngermembers of the profession (amongstwhom I count myself), lacking directexperience of older machines, thisinformation is both of general interestand a real asset. ‰


BOOK REVIEWS

relate to in vitro and laboratory studieswhich are debated in the penultimatechapter on in vitro testing and clinicalimplications. To be able to relate in vitrostudies to clinical wear studies, testprotocols are described in the finalchapter in which the differentcomponents of total wear can be relatedto the corrosive or mechanicalcontributions, and how one candifferentiate from in vivo studies onexplants which element has been thedominant to the wear seen. I would haveliked to have seen more detail of theconsequence of wear debris of differenttypes of bio-tribocorrosion on the joint orgingival tissues by histology as well asthe chemical effects but perhaps thatawaits a follow-up book on implantfailure caused by this corrosionphenomenon.

Like all publications in this series onbiomaterials produced by the publishers,the quality of the figures is exceptional,and scientists new to the field ofbiomaterials will certainly benefit fromthe information in this book.

Professor Julian Minns is a ConsultantClinical Scientist and holds an HonoraryChair in Medical Implant Design, ProductDesign Research (PDR) Centre at CardiffMetropolitan University, UK

Bio-Tribocorrosionin Biomaterials andMedical Implants

This book is acollection of 14chapters fromexperts,throughout theworld, incorrosion due towear and loadingin use withinhumans, a fieldso-called ‘bio-

tribocorrosion’. It ranges from thefundamentals of wear mechanisms andthe types of wear and environment

BIO-TRIBOCORROSION IN BIOMATERIALSAND MEDICAL IMPLANTSY. YAN (editor)Publisher: Woodhead Publishing LtdISBN 13: 9780857095404Pages: 407Price: £150

‰

Medical Imaging –Technology andApplications

The word‘technology’ isderived from theGreek techne. Ashort onlinesearch suggeststhat a wholebook could bewritten on howto translate

Later chapters feel somewhat lessfleshed out than the core content withwhich the book begins. At only 10 pageslong, Chapter 9 on hybrid SPECT-CTcan offer no more than an introductionto the subject, and the section on novelSPECT cameras in Chapter 8 includessome minor errors in its briefdescription of the D-SPECT camera.

Overall this book’s great strength liesin collecting together in one well-structured resource a strong foundationof knowledge on the design andoperation of traditional gamma camerasin a manner not found elsewhere.Whilst trainees themselves may beunwilling to purchase a book with sucha narrow focus I would certainlyrecommend it as a resource for lecturersand supervisors and as a key additionto the library of any nuclear medicinedepartment, particularly one hostingtrainee physicists.

Miss Elizabeth Howell is a ClinicalScientist in Nuclear Medicine atNewcastle Upon Tyne NHS HospitalFoundation Trust, Newcastle Upon Tyne,UK

which give rise to corrosion, toapplications of this phenomenon inorthopaedic and dental implants andtheir clinical implications.

Like all multi-author books, there isa large range of quality and informationfrom chapter to chapter and so-calledworld experts on some aspects of thephenomena don’t necessarily describetheir work as well as others. In somechapters a high level of knowledge inthe field is needed to appreciate andunderstand the data being presented,whilst others (the majority) clearlyoutline the basics and build up to thedescription and effects of whateveraspect of wear corrosion they aredescribing. This is particularly wellhighlighted in Part III of the book.

I enjoyed the early chaptersoutlining the effect of the surfacetopography and the chemicalenvironment on the bio- and tribo-corrosion effects, being an extension ofthe science of tribology (the study offriction, lubrication and wear) andcorrosion which is concerned with thechemical and electrochemicalinteractions between the implantmaterial and its environment. Theimportance of fretting corrosionespecially in orthopaedic implants isdescribed in many of the early chapters,less so in dental implants, between theplethora of modern materials such asceramics and metals.

The environment is also explored ingreat depth in Part II, especially theeffect of the very hostile constituents ofsynovial fluid in human joints and thechemicals in the oral cavity whichcontribute to the wear and corrosionseen in orthopaedic joint replacements,or tooth wear in dental applications. Onthis last application I was fascinated bythe largest chapter in the book in PartIII, on corrosion-resistant coatings fordental implants in which the differentmechanisms of bonding to substratesand the characteristics of differentmaterial combinations are clearlyexplained, with over 200 relatedreferences quoted. However, theyrightly emphasise that in vitro willnever be completely equivalent to invivo conditions. Even though Part III isentitled ‘Bio-tribocorrosion in theclinical environment’, the chapters only

THE GAMMA CAMERA – A COMPREHENSIVEGUIDERICHARD S. LAWSONPublisher: IPEMISBN-13: 978 1 903613 53 5Format: PaperbackPages: 296Price: £45




‰

techne, but my favourite translation,and one that seems appropriate for thecoverage in Medical Imaging: Technologyand Applications, is ‘cunning of hand’.The book’s strength is its coverage ofrecent, and impressive, developmentsin technology associated withestablished imaging modalities. Thereare notable chapters on capacitivemicromachined ultrasonic transducer(CMUT) imaging systems, fast-kVpswitching for dual-energy CT imaging,high-performance PET detectors,multicoil parallel receive MRI andsemiconductor flat-panel detectors formicro-CT.

The book is described by the editorsas a ‘broad-spectrum text’, intended toprovide a snapshot of some of thediverse fields that contribute to thefield of medical imaging. Thisdescription is entirely appropriate; thecoverage is broad (from optical imagingthrough the major imaging modalitiesto software methods) and up to date.This is an advanced text, intended forthose who already have knowledge ofthe imaging modalities. In addition tocovering recent advances in detectortechnology, the second focus of thebook is on applications. Here, chaptertopics include brain connectivitymapping with diffusion MRI, tracerkinetic analysis for PET and SPECT andreduction of respiratory artifacts inthoracic PET/CT. The chapters ontechnology and applications arepreceded by an enjoyable discussion onthe future of medical imaging. Thefuture of integrated circuits isemphasised, and this fits thetechnological focus of the later materialvery well.

There are multiple authors, but aconsistent and remarkably readablewriting style has been achieved. Each

chapter is complete in itself, and thereare only a few instances of overlapbetween chapters. One annoyingfeature is the variations in referencestyling across the chapters, but for thegeneral reader, who will look at onlyone or two chapters at a time, thisshould not be a major irritant. There are288 illustrations. Diagrams are clearlydrawn, and illustrations that use colourare reproduced both in monochromewithin the chapter and in colour in aninsert in the middle of the book.

The book would be a fine resourcefor graduate-level teachers wanting tointroduce some up-to-the-minuteexamples into their lectures, and forresearchers and innovators needing tobring themselves quickly up to speed.Beyond these groups, however, there issomething included for anyone with aninterest in medical imaging andcunning solutions.

Dr Elizabeth Berry is the Director ofElizabeth Berry Ltd (Berwickshire, UK) andspecialises in medical imaging. She tutorsfor the Open University and is a Fellow ofboth IPEM and IoP

on the subject. The book followsSpringer’s usual structure; subdividingthe subject into sensible parts. It flowsnicely from image acquisition to motionestimation and modelling beforeconcluding with the applications of themotion estimation. Correctly observingthat any reader likely to try 4Dradiotherapy will be restricted to thecapabilities of the equipment andsoftware they have available to them,every method for acquisition andmodelling is discussed with equal detailand the book has multi-vendorawareness throughout.

In addition to being written byauthors who are widely published intheir field, each chapter is painstakinglyreferenced and the end-of-chapterreference sections are extensive. Theyinclude publications from authors,journals and scientific meetings from allover the world and dating from the veryfirst work performed on 4Dradiotherapy. The referencing is a realadvantage – if any reader was interestedin any individual aspect, howeverspecific, the book gives them everythingthey need to find the more detailedpublished work.

The book seems predominantlyaimed at engineers, physicists andresearchers. It doesn’t shy away fromexplaining the complex mathematicaland statistical algorithms used for 4Dradiotherapy, which is a welcomeinclusion for those seeking to betterunderstand how their existing 4Dradiotherapy systems work from theoryto practice.

Much of the applications of motionestimation section is written from aclinical perspective; in these laterchapters, the tone changes and most ofthe complex mathematics disappears – aclear intention to make this sectionaccessible to oncologists and associatedmedical staff. There remains somecontent for the physicist, however; thissection contains an all-too-briefdiscussion of quality assurance duringimplementation though again with thesubject well referenced.

Every chapter starts with anintroduction to the latest sub-topic, andthese do sometimes repeat informationfrom earlier in the book, but theintroductions are brief enough that this

MEDICAL IMAGING – TECHNOLOGY ANDAPPLICATIONSTROY FARNCOMBE, KRZYSZTOF INIEWSKI(editors)Publisher: CRC PressISBN-13: 978-1-4665-8262-0Format: Hardback (also available as e-book)Pages: 732Price (publisher’s website): £95

4D Modeling andEstimation ofRespiratory Motionfor RadiationTherapy

Given the hugeamount of workpublished in thefield of 4Dmodelling andrespiratory motionin radiotherapy,this book providesa very welcomeone-stop reference

There are multipleauthors, but aconsistent and

remarkably readablewriting style has been

achieved

““


BOOK REVIEWS

‰ repetition is minimal. With so manydifferent authors there are somedifferences in writing styles, butsometimes this is welcome to allow thecontent to be accessible to a differenttarget audience. The book is most usefulas a reference for many different staffgroups, and as such would be a valuableaddition to any medical physics andengineering departmental bookshelf.

Mr Mark Worrall is a Clinical Scientist inDiagnostic Radiology and RadiationProtection, Radiation Physics at NinewellsHospital, Dundee, UK

HADRON THERAPY PHYSICS ANDSIMULATIONSNUNES, MARCOS D'ÁVILAPublisher: SpringerFormat: PaperbackISBN-13: 978-1461488989Pages: 95Price: £44.99 (paperback) or £35.99 (e-book)

4D MODELING AND ESTIMATION OFRESPIRATORY MOTION FOR RADIATIONTHERAPYJAN EHRHARDT, CRISTIAN LORENZ (editors)Publisher: SpringerISBN-13: 978-3-642-36440-2Format: HardbackPages: 340Price: £95.00

Just Published!The Rudolf Mossbauer Story by MichaelKalvius and Paul Kienle (Springer) featuresexpert reviews of the many applications ofthe ‘Mossbauer effect’ in a plethora ofsciences, including physics, chemistry,biology and medicine. Coverage includesthe history and development ofMossbauer’s Nobel-winning research.

Biomimetic Membranes for Sensor andSeparation Applications by Claus Helix-Nielsen (Springer) addresses thepossibilities and challenges in mimickingbiological membranes and creatingmembrane-based sensor and separationdevices. Recent advances in developingbiomimetic membranes for technologicalapplications are presented.

Radiation Damage in BiomolecularSystems by Gustavo Garcia Gomez-Tejedorand Martina Christina Fuss (Springer) coversadvances in radiation protection, includingresearch on radiation-induced damage atthe molecular level, radiation damagemodelling, biomedical aspects of radiationeffects and much more. It includes thework of research groups worldwide.

Hadron TherapyPhysics andSimulations

This is aninteresting andreadable slimvolume on particleradiotherapy whichis written from theSouth American/Brazilianperspective. Itconsists of fourmajor chapters

covering 95 pages with chaptersfocussed on history, an overview of thebasics of why hadron beams might be agood choice for cancer treatment and thefacilities that exist to deliver them,physics of particle accelerators andradiation dosimetry, and finally on theimportant role of radiation transportsimulations in this field.

There are no facilities for hadrontherapy in South America, apart from theexcellent work of the community ofresearchers and clinicians in Argentinaworking on boron neutron capturetherapy. In such a situation it is perhapsunderstandable that the benefits of

proton and carbon ion radiotherapy aregiven very great emphasis. This iscertainly beyond their benefits as provenin clinical trials and very likely wellbeyond their actual benefits in currentclinical practice. This is perhaps natural,partly from a desire to enthuse onpotential benefits to encourage others toengage with this field, and partly from adesire to be persuasive to policymakers.In order to achieve these desires thecapabilities of modern x-rayradiotherapy are repeatedlyunderestimated. It is not entirelyunreasonable to give such a one-sidedposition, since the field is developingthrough international efforts andresearch, and there are potentialtechnology improvements that willwiden and improve the capabilities ofparticle radiotherapy in the clinic. Thedevelopments may very well extend theclinical indications for which it trulyconfers advantage over modern x-rayradiotherapy.

This book does unfortunately containa sufficient number of questionablestatements to mean that it is somewhatunreliable as a reference text on thesubject. This is a great pity as inparticular the historical overview, thesections on accelerator design and someparts of the simulation chapter are veryinteresting and informative. As oneexample, the particle energies involvedin carbon ion therapy are variouslyreferred to as 350–450 MeV (p. 19) or 350MeV (p. 51). The energies areapproximately of this magnitude peratomic mass unit (amu), so in reality arein the approximately 4 GeV range. Theenergy/amu (or ‘/u’) is correctlyidentified in table 2.1. Furthermore, theuse of a duoplasmatron ion source ismentioned in a number of placesthroughout the book as if this was theonly ion source suitable for this field.This is far from the case. As a finalexample, on page 51 some data isreported of the numbers of radiotherapycases in Europe. A quite reasonablefigure of 20,000 cases per year per 10million of the population is given.However, this is followed by some dataon total numbers of patients treated peryear with protons and carbon ions. Theseare then, I think quite incorrectly,converted to percentages without

correction for the total population ofEurope, so the percentages quoted aredramatically overestimated.

Overall, I did enjoy this book – which isperhaps the most important message toconvey from this review. Some sectionslacked clarity but cited papers which I wassufficiently motivated to find and read, sothat was certainly beneficial for me.

Professor Stuart Green is the Director ofMedical Physics at the University HospitalsBirmingham (UK) and an Honorary Professorin the School of Physics and Astronomy,University of Birmingham (UK). He is a PastPresident of the British Institute of Radiologyand lectures widely on particle radiotherapyand BNCT, which are his main researchinterests

n Monitor Unit Calculations for External Photon and Electron Beams.

Report of the AAPM Therapy Physics Committee Task Group 71. Med Phys

2014; 41(3).

n Quantitative Nuclear Medicine Imaging: Concepts, Requirements and

Methods. IAEA Human Health Reports 9; January 2014. http://www-

pub.iaea.org/MTCD/Publications/PDF/Pub1605_web.pdf

n Managing Regulatory Body Competence. IAEA Safety Reports Series 79,

STI/PUB/1635; December 2013. http://www-pub.iaea.org/MTCD/

Publications/PDF/Pub1635_web.pdf

n Establishing a National Nuclear Security Support Centre. IAEA TECDOC

1734; February 2014. http://www-pub.iaea.org/MTCD/Publications/PDF/

TE-1734_web.pdf

n The Information Systems on Occupational Exposure in Medicine, Industry

and Research (ISEMIR): Interventional Cardiology. IAEA TECDOC 1735;

February 2014. http://www-pub.iaea.org/MTCD/Publications/PDF/TE-

1735_web.pdf

n Survey into the Radiological Impact of the Normal Transport of

Radioactive Material by Air. HPA (Public Health England), PHE-CRCE-006;

January 2014. http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/

1317140693852

n Safer Radiotherapy (September to November 2013 RT error data

analysis). Radiotherapy newsletter of Public Health England; January

2014. http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/

1317140696724

n European Guidelines on Medical Physics Expert (MPE). European Union,

Radiation Protection Number 174; February 2014. http://ec.europa.eu/

energy/nuclear/radiation_protection/doc/publication/174.pdf

n Radiation Protection in Nuclear Medicine. IPEM Report; March 2014.

n Metastatic Spinal Cord Compression (QS56). NICE.

http://www.nice.org.uk/nicemedia/live/14094/63861/63861.pdf

n Children and Young People with Cancer (QS55). NICE; February 2014.

http://www.nice.org.uk/nicemedia/live/14097/63824/63824.pdf

n Vision For Radiotherapy: 2014–2024. Cancer Research UK/NHS England;

March 2014. https://www.cancerresearchuk.org/sites/default/files/

policy_feb2014_radiotherapy_vision2014-2024_final.pdf

n Public Accounts Committee – Thirty-Sixth Report on Confidentially Clauses

and Special Severance Payments. December 2013.

http://www.publications.

parliament.uk/pa/cm201314/cmselect/cmpubacc/477/47702.htm

n Standard Practice for Marking Medical Devices and Other Items for Safety

in the Magnetic Resonance Environment. IEC 62570, ed1.0; February 2014.

n Radiation Protection Instrumentation – Security Screening of Humans –

Measuring the Imaging Performance of X-ray Systems. IEC 62709, ed1.0;

February 2014.

n Scaling the Heights: An Overview of Higher Specialist Scientific Training

(HSST) in Healthcare Science, Modernising Scientific Careers. Health

Education England; January 2014. http://hee.nhs.uk/wp-content/uploads/

sites/321/2014/01/Scaling-the-Heights-final.pdf

n Modernising Scientific Careers Curricula, Network Update, Scientific

Training Programme (STP) Curricula (2013/14), Practitioner Training

Programme, HSST Curricula for 2014/15.

http://www.networks.nhs.uk/nhs-networks/msc-framework-curricula

http://www.nhsemployers.org/planningyourworkforce/modernising-

scientific-careers/msc/pages/msc.aspx

http://www.nhsemployers.org/PLANNINGYOURWORKFORCE/MODERNISIN

G-SCIENTIFIC-CAREERS/TOOLSRESOURCES/Pages/Toolsandresources.aspx



The Physics of Radiation Therapy, 5thedition by Faiz M. Khan and John P.Gibbons (Lippincott Williams & Wilkins)helps you expand your understanding ofthe physics and practical clinicalapplications of advanced radiationtherapy technologies. This title also helpsthe entire radiation therapy team –radiation oncologists, medical physicists,dosimetrists and radiation therapists.

Electro-Magnetic Tissue Properties MRIby Jin Keun Seo, Eung Je Woo and UlrichKatscher (Imperial College Press) is the firstbook that presents a comprehensiveintroduction to and overview ofelectromagnetic tissue property imagingtechniques using MRI, focussing onmagnetic resonance electrical impedancetomography (MREIT), electricalproperties tomography (EPT) andquantitative susceptibility mapping(QSM).

Handbook of Ultra-Short Pulse Lasersfor Biomedical and MedicalApplications by Joseph Neev (McGraw-HillEducation) is written for biophotonics

scientists and engineers who arecollaborating with medical professions indeveloping the medical tools which utiliseultra-short pulse lasers.

The History of Physics in Cuba by AngeloBaracca, Helge Wendt and Jürgen Renn(Springer) brings together a broadspectrum of authors, both from inside andoutside of Cuba, who describe thedevelopment of Cuba’s scientific systemfrom the colonial period to the present.

Novum Organum II – Going Beyond theScientific Research Model by ChrisEdwards (Rowman & Littlefield) shows thatthe West’s university and its scientific andmedical systems all stem from Bacon’sphilosophy. Thinkers who can studyacross disciplines and form analogies havebeen making impressive breakthroughs.

Pattern Recognition and Signal Analysisin Medical Imaging, 2nd edition by AnkeMeyer-Baese and Volker J. Schmid (AcademicPress) delves deep into the details ofstatistical and syntactic patternrecognition, the theory and applications of


neural networks, fuzzy logic, computer-aided diagnosis systems and much more.

The Cambridge Companion to Einstein byMichel Janssen and Christoph Lehner(Cambridge University Press) is the firstsystematic presentation of the work ofAlbert Einstein, comprising 14 essays byleading historians and philosophers ofscience that introduce readers to his work.

Smashing Physics by Jon Butterworth(Headline) is the first insider account of thework at the Large Hadron Collider atCERN, the discovery of the Higgs particle –and what it all means for ourunderstanding of the laws of nature.

Clinical Engineering – A Handbook forClinical and Biomedical Engineers byAzzam Taktak, Paul Ganney, David Long andPaul White (Elsevier) is intended forprofessionals and students in the clinicalengineering field who need to successfullydeploy medical technologies. The bookprovides a broad reference to the coreelements of the subject and draws from theexpertise of a range of experienced authors.

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In the 17th and 18thcentury, electricity was aphenomenon associated

with friction“

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HISTORICAL FEATURE: A HISTORY OF BIOMEDICAL ENGINEERING

Stanley Salmons brings the second part of his historical series, showing how

research into the nature of electricity led to improved measurement techniques

PART 2:Discoveries at thedawn of the electronic era

he nature of the electric charge took someyears to emerge. In the 17th and 18thcenturies, electricity was a phenomenonassociated with friction between substanceslike amber and fur, and glass and silk. In fact

the Greek word for amber, elektron, and its Latinequivalent, electricus, are the origins of our words‘electron’ and ‘electricity’. In 1733, C.F. Du Faydistinguished two kinds of electricity: vitreouselectricity, generated by rubbing glass with silk, andresinous electricity, generated by rubbing amber withfur. It was Benjamin Franklin who, with characteristiclucidity, applied Occam’s razor to make the leap fromthis ‘two-fluid’ theory to a single-fluid theory (1747): ‘Toelectrise plus or minus no more needs to be known thanthis, that the parts of the tube or sphere that are rubbeddo, in the instant of the friction, attract the electrical fire,and therefore take it from the thing rubbing; the sameparts, immediately as the friction upon them ceases, aredisposed to give the fire they have received to any bodythat has less’.1

This extraordinary insight was also arrived at byWilliam Watson. It was nearly 150 years before GeorgeJohnstone Stoney described the quantised nature of thecharge. He proposed the name ‘electron’ for it, and thiscame to be applied to the subatomic particle itself afterJ.J. Thomson discovered it in 1897 (Thomson’s initialterm was ‘corpuscle’).

Thomson reached his conclusions throughexperiments on the electrostatic and magnetic deflectionof cathode rays, which were generated within anevacuated glass apparatus known as a Crookes tube(figure 1). In the same year as Thomson’s discovery, KarlFerdinand Braun added a phosphor coating to theCrookes tube, so inventing the first cathode ray tube.Braun went on to devote himself to wireless telegraphy,inventing among other things the crystal diode (or cat’swhisker diode) and the inductively coupled antenna; heshared the 1909 Nobel Prize with Marconi.

Braun’s cathode ray tube employed a cold cathode.Subsequently such tubes were fitted with a heatedcathode, based on the so-called ‘Edison effect’. Edisonhad shown in 1880 that a heated wire in an evacuatedglass bulb gave rise to a current if presented with apositively, but not a negatively, charged foil; aphenomenon now known as thermionic emission. Theheated cathode, and other improvements, would lead

gradually to cathode ray tubes that were moredependable and commercially viable. This wasparticularly true of the 1931 design by V.K. Zworykin,which was adopted by General Radio. Later we willdescribe Zworykin’s profound influence on thedevelopment of biomedical engineering.

John Ambrose Fleming exploited thermionicemission in the vacuum diode, which he patented in1904. He showed that this device could be used to detectradio waves. Lee de Forest added a further electrode,the control grid. The de Forest valve, patented in 1908(and known after 1919 as the triode), was a moresensitive detector of radio waves. The valve amplifierhad been born.

Valve amplifiersThe potential of thermionic valves began to be exploitedduring the First World War for communicationspurposes. After the war their ability to amplify the weakelectrical signals generated by excitable tissues meantthat they were quickly recruited for both physiologicalresearch and clinical applications. The speed of thisadoption is well illustrated by ground-breaking workon the generation and conduction of nerve impulses.H.S. Gasser and J. Erlanger built a three-stage valveamplifier (figure 2)2 and in 1922 used it to display anerve impulse on a cathode ray tube.3 E.D. Adrian(figure 3), returning to Cambridge after clinical workduring the war, began his own experiments, extendingBowditch’s work of 50 years earlier on the ‘all-or-nothing’ character of the nerve impulse.4 In 1922 he wasusing a string galvanometer. Four years later he waspublishing results obtained with a three-stage RC-coupled valve amplifier.5 This was based on detailssupplied by Gasser and was built for him by Messrs.W.G. Pye & Company.

Adrian recorded the amplified signals with acapillary electrometer designed by Keith Lucas.6

Following Gasser’s pioneering use, however, thecathode ray tube soon became the display device ofchoice. When combined with a valve amplifier it couldrecord high-speed phenomena with much greaterfidelity than previously possible, since the essentiallyweightless beam of electrons eliminated inertia. InBraun’s original tube the signal deflected the beam inthe vertical direction but there was no horizontaldeflection; instead, he used a rotating mirror to spread

T

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the display. The horizontal sweep was introducedsoon afterwards by Jonathan Zenneck in 1899, usingmagnetic deflection. If this was generated by a saw-tooth waveform of known frequency then thehorizontal travel of the beam could be related directlyto time.

While such devices could record repetitivephenomena such as the electrocardiogram and trains ofnervous impulses (figure 4), it was tricky to study thefeatures of the individual waveforms, as these wouldcrop up at different intervals after the start of the traceand therefore at any point across the sweep. Otto H.Schmitt solved this problem for the Biophysics ResearchUnit at University College London (UCL) bydeveloping a circuit which was to find much widerapplication. Schmitt had joined the Unit as a PhDstudent in about 1937. The configuration,7 which isknown even after the passing of the valve era as aSchmitt Trigger, was incorporated into the timebasecircuit of his electrophysiological recording system. Thisapparatus was used by Bernard Katz for nerve potentialstudies and by J.Z. Young at Oxford for his fundamentalwork on the giant squid axon. In 1946, oscilloscopesincorporating the triggered sweep were introduced bythe Tektronix company and this has been a feature ofsuch instruments ever since. Interestingly, Schmitt’srecording system at UCL was restored after the SecondWorld War and remained in use until the end of the1950s.

The early valve amplifiers presented problems forphysiologists. Bioelectric signals were small and had tobe detected in the presence of amplifier noise andelectromagnetic interference, both high- and low-frequency, the former from increasingly powerful andprevalent radio waves, and the latter from the mainselectricity supplies introduced around the turn of the19th century. (Aware of this problem, Keith Lucas hadarranged for some rooms in the new PhysiologicalLaboratory at Cambridge to receive their electricitysupply entirely from a storage battery!) Even underideal experimental conditions the apparatus amplifiedboth the signals and the interference (note the noiselevel in figure 4, for example). It was helpful to earththe preparation or subject, to shield the apparatus as faras possible, and to detect the signal between twoindependent electrodes, but the real answer required afurther step. The biological source generates adifference in potential between the electrodes (anti-phase signal), whereas the interference appears at eachelectrode in an almost identical way (in-phase, or‘common mode’ signal). The solution was therefore adifferential amplifier that would be inherently lesssensitive to in-phase signals (rejection) and wouldamplify the anti-phase signals more than the in-phasesignals (discrimination). Starting in the 1930s a varietyof configurations were developed to achieve this.8–12

Most, but not all, of these configurations were based onsymmetry of the circuit, and even companies such asTektronix had to select the valves to achieve it. (Theauthor’s first Eureka moment, and the subject of hisfirst full paper, was a configuration that obviated theneed for such selection.13)

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FIGURE 1. Crookes Tube (Wellcome Images)

FIGURE 3. E.D. Adrian

FIGURE 2. Gasser’s three-stage triode amplifier

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Artificial pacemakersI should mention at this point the evolution of theartificial cardiac pacemaker. Despite the rapiddevelopments in electronics, it seems that the possibilityof using valves for anything other than amplification wasinitially overlooked. Thus what is popularly regarded asthe first artificial pacemaker was purely mechanical.Figure 5 illustrates this device, which was reported byAlbert S. Hyman in 1932. Nearly 20 years would elapsebefore an external pacemaker based on valve technologywas built by John A. (‘Jack’) Hopps at the University ofToronto; figure 6 is believed to show this mains-poweredapparatus. The convenience, comfort and relative safetyof implantable pacemakers would await developments inthe semiconductor field.

Diagnostic applicationsThanks at least in part to the new valve amplifiers, the1930s was a time of rapid progress in the study of thecentral nervous system, notable strides being made byE.D. Adrian, J.C. Eccles, Charles Scott Sherrington andothers. These studies had their clinical counterpart.

Electroencephalography (EEG) would be an obviousbeneficiary of progress in amplifier design because thesignals were so small, in the region of 100 μV. Thescepticism that had originally surrounded alpha waveswas dispelled at a meeting of the Physiological Society in1934 when E.D. Adrian, working with B.H.C. Matthewsand using an improved amplifier, proved that the so-called Berger Rhythms could be recorded through theintact skull, and they mapped them to the occipitalregion.14 This work led to the description of EEG changesin epilepsy and other neurological conditions. EEGrecording began to be used clinically around 1936. Eventhese small and variable signals were capable of furtheranalysis. One of the first methods was that of Grass andGibbs, who recorded the signal on 35 mm film, whichthey spliced to form a loop. This was passed at 100 timesthe recording speed between a slit light source and aphotoelectric cell to reproduce the signal repeatedly. Byusing a variable filter they could then construct afrequency spectrum.15 Albert M. Grass went on toestablish the Grass Instrument Company, which made arange of instruments for physiological and biomedicaluse, and which continued as Grass Technologies after itbecame a subsidiary of first Astro-Med Inc. and thenNatus Neurology.

Electromyography underwent a parallel development,but although the signals were an order of magnitudelarger, their interpretation initially presented a challenge.The first extensive clinical study of electrical potentialsgenerated by muscle was described in a book by HansPiper in 1912.16 In 1929, E.D. Adrian and Detlev Bronkdemonstrated the functional activity of single motor unitsto the American Physiological Society, using the coaxialelectrode invented by Bronk and a valve amplifierconnected to a loudspeaker.17 At the same time DerekDenny-Brown’s insightful studies were laying thefoundations for the clinical use of the technique; anexample is his lucid distinction between fibrillation andfasciculation.18

And then came the war.

FIGURE 4. Nerve impulses recorded by Adrian from the central nerve cord of acaterpillar (Wellcome Images)

▼

FIGURE 5. Hyman’s artificial pacemaker (1932)▼

FIGURE 6. Apparatus believed to be the external valve-based pacemakerdeveloped by John A. Hopps at the University of Toronto (1951)

▼

‰



The Second World WarWars change many things. They determine the futureof peoples, their governance and their national borders.They also accelerate technical and scientificdevelopment and put a premium on man’s ingenuityfor achieving urgent objectives.

In September 1939, along the Eastern coastline of theUK from the Orkneys to the Isle of Wight stood silentsentinels. The 360-foot-high steel towers and 240-foot-high wooden towers were the CH (Chain Home) RDFstations, RDF (Range, Direction Finding) being whatwe know today as RADAR. The decision of thegovernment in 1934 to give priority to the developmentof RDF was prompted by ‘Three Wise Men’: HenryTizard, a chemist, A.V. Hill, a physiologist, and P.M.S.Blackett, a physicist. All had served during the FirstWorld War and they formed part of a small committeefor the Scientific Survey of Air Defence. The fate of thecountry, and the lives of thousands of civilians andmilitary personnel, were to depend heavily on theadvice accepted from these eminent scientists and frommany others, including the physicist R.V. Jones(scientific counter-intelligence)19 and the zoologist SollyZuckermann (air operational research).20

Scientists and technologists were key to the wareffort at every level. Mention may be made here ofJohn Randall and Harry Boot, whose development ofthe cavity magnetron made possible compactcentimetre-wavelength radar sets which could beinstalled on ships and aircraft. A.D. Blumlein, arguablythe greatest British electronic engineer of the century,designed the circuitry of the world’s first high-definition (405 lines, high definition at that time)television system, and patented circuits such as theMiller integrator, the long-tailed pair and the cathodefollower (versions of which have propagated throughall the semiconductor revolutions which have occurredsince). Tragically he was killed in 1942 when theHalifax bomber in which he was testing the new H2Sradar equipment crashed, killing all on board. Inpassing, we may note that the leader of the teamcharged with developing this S-band airbornetargetting radar was Bernard Lovell, who subsequentlybecame a pioneer of radio astronomy and the firstDirector of the Jodrell Bank Observatory.

Such people served alongside undergraduates whohad been reading subjects as disparate as zoology,mineralogy, mathematics, metallurgy and chemistry,and who had been recruited with the assurance thatthey would be allowed to return to their studies whenthe emergency was over. The contribution ofmathematicians within the Government Code andCypher School (later GCHQ) at Bletchley Park is nowwell recognised. So is the development by Post Officeengineer Tommy Flowers of the Colossus computer, a2,400-valve behemoth, to decipher the Ultra codes. Butthe success of this entire enterprise depended on thereliable interception of radio messages from as faraway as the Russian front. This required receivers ofever-increasing sensitivity. Thus, radio engineers wererubbing shoulders with physiologists, chemists andmathematicians, all of whom were developing

techniques and technical devices for protecting thepopulace and furthering the country’s offensive ordefensive capability.

When the war was over, many of these deployed theirnewly acquired skills and knowledge in industry inacademic departments of mathematics, physics andengineering – and in the life sciences. And by a variety ofroutes the fruits of the frenetic wartime pace ofdevelopment began to trickle into biology and medicine.



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REFERENCES1 Glenn WWL. Benjamin Franklin: physician and

philosopher. Am J Surg 1985; 149: 426–34.

2 Gasser HS, Newcomer HS. Physiological action currents

in the phrenic nerve. An application of the thermionic

vacuum tube to nerve physiology. Am J Physiol 1921; 57:

1–26.

3 Gasser HS, Erlanger J. A study of the action currents of

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