medical exposure to patients from diagnostic equipments in

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1

Medical Exposure to Medical Exposure to

Patients from Diagnostic Patients from Diagnostic

Equipments in TaiwanEquipments in Taiwan

HuiHui--Yu Tsai, Ph.D.Yu Tsai, Ph.D.

Assistant professorAssistant professor

School of Medical Imaging and Radiological SciencesSchool of Medical Imaging and Radiological Sciences

Chung Shan Medical University Chung Shan Medical University

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ImportanceImportance

Quality Control Quality Control

in Diagnostic Radiologyin Diagnostic Radiology20022002AAPM Report AAPM Report

No. 74No. 74

Patient Patient DosimetryDosimetry for X Rays used in for X Rays used in

Medical ImagingMedical Imaging20052005ICRU ICRU

report 74report 74

Managing Patient Dose in Digital Managing Patient Dose in Digital

Radiology Radiology 2005/42005/4ICRP ICRP

publicationpublication 9393

Managing Patient Dose in MultiManaging Patient Dose in Multi--

Detector Computed Tomography Detector Computed Tomography 2007/112007/11ICRP ICRP


Managing Patient Dose in ComputedManaging Patient Dose in Computed

TomographyTomography2001/122001/12ICRP ICRP


TitlesTitlesYearsYears

2

3

UNSCEAR 2000UNSCEAR 2000

�� Contributions to Contributions to

frequencyfrequency�� Contributions to Contributions to

collective dosecollective dose

Chest

15%

GI tract

17%CT

34%

Other

8%

Head

1%

Abdomen

2%

Mammography

1%

Angio/

Interventional

10%

Spine/bone

12%

Collective dose

Chest

42%

Spine/bone

29%

Angio/

Interventional

1%

Mammography

2%

Abdomen

5%

Head

6%

Other

5%CT

5%

GI tract

5%

Frequency


4

Contributions to Contributions to

global collective doseglobal collective dose


3

5

Effective dosesEffective doses

77Ba enemaBa enema

1.51.5Ba swallowBa swallow

0.70.7PelvisPelvis1010--2020PelvisPelvis

1.01.0AbdomenAbdomen1010--2020AbdomenAbdomen

0.020.02Chest PAChest PA88ChestChest

0.070.07SkullSkull22HeadHead

Effective Effective

dose (mSv)dose (mSv)Radiographic Radiographic

examinationexaminationEffective Effective

dose (mSv)dose (mSv)CT CT

examinationexamination

ICRP-87

6

Dose Indexes

Radiology Mammography CTFluoro/

Angio

DAPCTDI

DLPESDESD

Effective

Dose

Effective

DoseMGD

Effective

Dose

4

7

Frequency distribution Frequency distribution

of radiographic proceduresof radiographic procedures

Chest

41.32%

Spine/bone

23.14%

GI tract

10.54%

CT

4.34% Other

2.48%

Head

5.99%

Abdomen

11.98%

Mammography

0.04%

Angio/

Interventional

0.18%

Frequency

Taiwan (1991-1996)

UNSCEAR 2000 (Taiwan)UNSCEAR 2000 (Taiwan)

RadiographyRadiography

Tung Tung et. alet. al., Med. Phys. (2001)., Med. Phys. (2001)

8

Chest PA procedureChest PA procedureRadiographyRadiography


5

9

kVpkVp and and mAsmAsRadiographyRadiography


a. These values are survey findings for hospitals.

b. These values are survey findings for private practice.

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Entrance surface doses &Entrance surface doses &

Guidance level determinationGuidance level determination



6

11

Guidance levelsGuidance levelsRadiographyRadiography


12

Effective dosesEffective doses



7

13

25None CCT-W seriesHITACHI

1GE.i

GE QX/i, LightSpeed,

LightSpeed Plus

7GE.gFGE Prospeed

8GE.c

GE HiLight, HiSpeed, CT/i (No

SmB)

9GE.eGE Max

9GE.d

B and B’GE HiSpeed CT/i with

SmartBeam

12GE.fDGE Pace, Sytec

12GE.hAGE FX/i, LX/i

General

Electric

NumberImPACT

Code

Measured

CodeScannerManufactures

146 CT scanner survey 146 CT scanner survey CTCT

Tsai Tsai et. alet. al., Med. Phys. (2007)., Med. Phys. (2007)

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NumberImPAC

T Code

Measured

CodeScannerManufactures

1TO.eXpress HS1

4TO.dXvision / EX

6TO.iToshiba Auklet

19TO.aTCT 600

Toshiba

1SI.hHi Q

1SI.gPlus, DXP, Plus-S

4SI.jHVolume Zoom, Access

5SI.iGBalance, Emotion

5SI.dSomatom Plus 4 Series

7SI.e

Somatom AR-C, AR.SP,

AR-T

Siemens

3SH.aSCTShimadzu

7PI.bEPQ SeriesPicker

CTCT

8

15

592 (191)17 (4)335 (80)222 (60)121 (3)Abdomen-

pelvis

410 (308)22 (15)187 (53)295 (228)121 (4)Pelvis

453 (349)22 (15)204 (54)292 (229)121 (3)Abdomen

456 (33)20 (15)223 (87)271 (223)122 (5)Chest

665 (377)55 (31)122 (24)343 (223)121 (5)Head

DLP (mGy cm)CTDIw(mGy)L (cm)mAskVpExamination

Technical factors and Technical factors and

dose descriptors dose descriptors

CTCT


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10 (3.1)8.4 (2.7)12 (3.7)2.2 (2.5)18 (5.8)7.8 (2.4)Abdomen-

pelvis

7.6 (5.7)5.7 (4.3)9.5 (7.1)3.6 (3.2)23 (17)6.0 (4.7)Pelvis

7.4 (5.8)7.0 (5.4)7.9 (6.2)0.1 (0.1)4.5 (6.7)5.2 (4.3)Abdomen

8.4 (6.5)6.4 (5.2)Chest

1.6 (0.9)2.5 (1.5)Head

Effective

(Average)

Effective

(Male)

Effective

(Female)TestesOvariesRBMExamination

Organ and Effective Doses Organ and Effective Doses CTCT


9

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Guidance level determinations Guidance level determinations


CTCT

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Guidance levelsGuidance levels

250 (87 %)24 (86 %)Adrenals

320 (77 %)24 (80 %)Kidneys

900420 (77 %)3524 (81 %)Liver-Spleen-Pancreas

570520 (83 %)3525 (80 %)Routine Pelvis

780750 (89 %)3525 (80 %)Routine Abdomen

650580 (80 %)3024 (83 %)Routine Chest

1050850 (83 %)6072 (85 %)Routine Head

ECThis Work*ECThis Work*

Guidance Level on

DLP (mGy cm)

Guidance Level on

CTDIw(mGy)

Examination

CTCT


10

19

Estimates of effective dosesEstimates of effective doses

DLP DLPE E= ×

CTCT


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CTDICTDIww, DLP, & effective dose, DLP, & effective doseCTCT


11

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What can operators doWhat can operators do……??�� Limit the scanned volumeLimit the scanned volume

�� ReduceReduce mAsmAs valuesvalues

�� Use automatic exposure Use automatic exposure ��1010--50% dose reduction in documented50% dose reduction in documented

��without any loss of image qualitywithout any loss of image quality

�� Use of spiral CT with pitch factor>1 and calculation of Use of spiral CT with pitch factor>1 and calculation of overlapping images instead of acquiring overlapping single scansoverlapping images instead of acquiring overlapping single scans

�� ShieldShield superficial organs superficial organs

�� Separate factors for children. Can reduce dose by a factor of 5 Separate factors for children. Can reduce dose by a factor of 5 or or moremore

�� Use partial rotation e.g. 270 degree in Head CT Use partial rotation e.g. 270 degree in Head CT

�� Adequate selection of image reconstruction parametersAdequate selection of image reconstruction parameters

�� Use of zUse of z--filtering with multifiltering with multi--slice CT systemsslice CT systems

�� Record of dose, exposure factorsRecord of dose, exposure factors

ICRP-87

CTCT

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SummarySummary

�� Dose indexesDose indexes

�� Guidance levelsGuidance levels

�� Effective dosesEffective doses

�� Survey resultsSurvey results

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ReferencesReferences

�� UNSCEAR (2000), UNSCEAR (2000), ““Sources and Effects of Ionizing Radiation.Sources and Effects of Ionizing Radiation.””

�� ICRP (2001), ICRP (2001), ““Managing Patient Dose in Computed Managing Patient Dose in Computed Tomography,Tomography,”” Report No. 87.Report No. 87.

�� C. J. Tung C. J. Tung et. al. et. al. (2001), (2001), ““Determination of Guidance Levels of Determination of Guidance Levels of Dose for Diagnostic Radiography in TaiwanDose for Diagnostic Radiography in Taiwan, , ”” Med. Phys. Med. Phys. 28:85028:850--857.857.

�� H. Y. Tsai H. Y. Tsai et. al. et. al. (2007), (2007), ““Survey of Computed Tomography Survey of Computed Tomography Scanners in Taiwan: Dose Descriptors, Dose Guidance Levels, Scanners in Taiwan: Dose Descriptors, Dose Guidance Levels, and Effective Doses,and Effective Doses,”” Med. Phys. 34: 1234Med. Phys. 34: 1234--1243.1243.

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