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The SBRT Ch∞inIntroduction to the Complexities of SBRT delivery

THE SBRT CHAINIntroduction to the Complexities of SBRT

Daniel TanCourse DirectorAssociate ConsultantDepartment of Radiation OncologyNational Cancer Centre Singapore


Aims:

1) Provide a Basic Overview of the SBRT Process2) Set Context for Subsequent Talks3) Demonstrate the Importance of Each Link4) Deliver some Take Home Messages


WHAT IS SBRT:

STEREOTACTIC- a procedure during which a target lesion is localized relative to a know three dimensional reference system.

SBRT is a specialized form of Cancer treatment whereby high doses of radiation are delivered in large fraction sizes over a short course of treatment


WHAT IS SBRT:

By accurately Localizing the target through imaging and immobilization, and creating highly conformal doses around the target, with steep dose gradients outside of it, extremely high doses of ablative radiation can be delivered to the target with minimal side effects to normal tissue.


It is a Different Kind of Operation with the Same Objective of exterminating the enemy with minimal collateral losses


Not an Issue of Good or Bad – Just Different

Different Approaches are required In Oncology


SBRT leverages on Technology to exploit the therapeutic ratio afforded by a highly conformal dose distribution and steep dose gradients around an accurately localized target

All the bells and whistles are really only to achieve the above.Of course the optimal dose fractional matters, but we are talking about delivery here.

Since we are depending on technology and processes to achieve our therapeutic goals, we need to master them to delivery good SBRT


The greater the capability, The higher the complexity

The higher the complexity, The larger the number of steps and the greater the skills required

The larger the number of steps, The more people are involved

The more people are involved, More coordination is needed

The greater the skills required, More training is needed

To ensure the whole system functions, it actually needs to be tested as a whole and not just individual components.


Basic:

Clinical Setup-

Logistical, ManpowerFor accurate diagnosis, imaging, pathology and stagingFor discussion and decision of a sound treatment plan

Multi-Disciplinary Framework-

National, Institutional, Sub-groups evidence-based guidelines/protocols for each specific cancer and stage.


Basic Radiation Oncology Facility:

Adequate EquipmentAdequate Manpower Adequate ExpertiseAdequate SystemsAdequate Support

1D – 2D – 3D – IMRT – 4D – SBRT Can we actually skip these steps?


Getting There:

Modifying Existing Systems for SBRT delivery Purchasing Integrated System for SBRT delivery

Physics Acceptance, Commissioning, QA of these systemsClinical Implementation of Specific SBRT programs

Know how it worksProve your machine works and to what degreeMaintain it to workMaximise its capabilitiesVerify that it works on your patient.


Now the Fun part:

Immobilization

How accurate are these?What is accurate enough?


Image Acquisition and Registration:

CT Scan (4-16-64 slices)MRI – 2D vs VolumetricFusion Algorithms- Rigid, Deformable, etc

Target and OAR delineation:Anatomy, Patterns of Failure, Consensus Based

Target Prescription and OAR tolerances:Ph1 dose escalation studies, Ongoing research


Treatment Planning: Conformal Beams, Dynamic Arcs, Non-coplanar beams, Isocentric/Non-isocentric, IMRT, VMAT

IGRT and correction strategies:Image acquisition- ROI, Fusion Algorithm, Tolerance Levels

Motion Management:Passive- 4D CTActive- Abdominal Compression, Gating, Tracking

Intra-fraction Motion (non-respiratory):Prostate and Spine motionPatient intra-fraction motion


Machine QA: Are machines delivering as they should?

Process QA: Is each process robust and integrated?

Patient specific QA: Are we treating the right patient with the right plan?

Follow-Up: Is the patient responding as is expected?

Contributing to the evidence: Reporting error and results


THE RADIATION BOOMA Pinpoint Beam Strays Invisibly, Harming Instead of HealingBy WALT BOGDANICH and KRISTINA REBELOPublished: December 28, 2010

Marci Faber is nearly comatose after a treatment mistake.

Evanston Hospital in IllinoisTrigeminal NeuralgiaModified SystemCone in PlaceFailure in setting backup jaws

http://topics.nytimes.com/top/reference/timestopics/people/b/walt_bogdanich/index.html?inline=nyt-per


Others:

Florida: 2004-2005, 77 patients. Calibration Error (measurement of output factor)Toulouse, France: Apr 06-07, 145 patients – 31% 12 mth actuarial rate of trigeminal neuropathy in 32 acoustic neuromaSpringfield, Missouri late 2004-2009


Dosimetric Impact of Motion:

Spine:Precision required for dose-escalated treatment of spinal metastases and implications for image-guided radiation therapy (IGRT)Guckenberger et al Green Journal 2007

‘To keep the dose distribution to the spinal cord within ±5% (±10%) of the prescribed dose, maximum tolerable errors of 1mm (2mm) in the transversal plane, 4mm (7mm) in superior–inferior direction and maximum rotations of 3.5° (5°) were calculated on average. The translational and rotational component of clinically observed set-up errors increased D5spine by 23±14% and 3±2% on average, respectively.’


Dosimetric Impact of Motion:

Brain: Dosimetric consequences of translational and rotational errors in frame-less image-guided radiosurgery.Guckenberger et al Green Journal 2012

‘Each 3D set-up error of 1 mm decreased target coverage and dose conformity by 6% and 10% on average, respectively, with a large inter-patient variability. Pre-treatment correction of translations only but not rotations did not affect target coverage and conformity. Post-treatment errors reduced target coverage by >5% in 14% of the patients. A 1 mm safety margin fully compensated intra-fractional patient motion.’


Multi-Stepped ProcessEvery link in the Chain MattersEvery link can be quite sophisticatedEach Institution needs to design its own program according to its aims and specifications- Cannot cut and paste protocol

Understand Concept, Understand Key Principles, Understand Equipment and Put them all together to achieve the intended Goal


Making Sense of the Course Program:

Clinical Setup: Learn from Yamanashi, MSKCC, NCC experience and also existing setups in RCA states

Multi-disciplinary Oncological Framework: Appreciate the Body of Evidence supporting SBRT and its current acceptance in the management of specific subsites

Integrated Delivery System and Quality Assurance: Machine Talks to appreciate state-of-the-art delivery systems, Physics talks to show the efforts required to keep these systems operationally ready

Technical Specifications unique to SBRT of each subsite: Case presentations, NCC DRO Visit, Journal Club to demonstrate specific requirements for site-specific SBRT


Can you buy a plane and go to war?


Can you buy a machine and do SBRT?


So much coordination required just to land a plane-Unlike infantry Ops


COORDINATION

INTEGRATION


Don’t Forget Your Wingman!

PilotWSO (Weapons System Officer)

Radiation OncologistMedical Physicist

F16DRSAF


It is more than RO and MPRTTs, Nurses, Technicians etc etcEveryone in the chain can contributeEveryone in the chain can do harm


Take Home Messages:

1) A Sexy Machine alone cannot delivery SBRT2) SBRT delivery is a highly complex process3) Successful SBRT delivery depends on the expertise of the WHOLE team4) Developing SBRT capabilities requires capital and commitment 5) This RTC aims to demonstrate the breadth of a clinical SBRT program6) With this knowledge, National Project Teams can work in an informed

manner in coordinating the setup of their respective programs

the sbrt ch ∞ in

Documents

sbrt chinintroduction

delivery good sbrt

d sbrt ca

sbrt processset context

localized target

high doses of radiation

target lesion

steep dose gradients