bushong, stewart - ahra.org filestewart carlyle bushong, sc.d. baylor college of medicine houston,...

8/3/2010

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Stewart Carlyle Bushong, Sc.D.Baylor College of Medicine

Houston, Texassbushong@bcm.edu

…because one size does not fit all

Stewart Carlyle Bushong, Sc.D.Baylor College of Medicine

Houston, Texassbushong@bcm.edu

8/3/2010

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ObjectivesRadiation Sources and IntensityRadiation Dose-Response RelationshipsALARA C di l P i i lALARA – Cardinal PrinciplesDeterministic/Stochastic Imaging Modalities (R&F, CT, DR)Imaging Economics

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ObjectivesRadiation Sources and IntensityRadiation Dose-Response RelationshipsALARA C di l P i i lALARA – Cardinal PrinciplesDeterministic/Stochastic Imaging Modalities (R&F, CT, DR)Imaging Economics

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…because one size does not fit allThe Alliance for Radiation

Safety in Pediatric Imaging13 societies with representation from radiology, pediatrics, and medical physicsThe risk of death from cancer is about 1 in 5The risk is cumulative; each CT increases risk by 1/1000

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ObjectivesRadiation Sources and IntensityRadiation Dose-Response RelationshipsALARA C di l P i i lALARA – Cardinal PrinciplesDeterministic/Stochastic Imaging Modalities (R&F, CT, DR)Imaging Economics

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Radiation UnitsExposure……….. mR …… mGyTissue Dose………mrad…...mGyEff ti D SEffective Dose… mrem…..mSv

Resp

onse

Dose

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Resp

onse

BB

DoseDeterministic

Stochastic

NaturalIncidence

20%

0%

DeterministicNon-LinearThresholdS it i ith dSeverity increases with dose

StochasticLinearNon-ThresholdI id i ith dIncidence increases with dose

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Resp

onse

BB

DoseDeterministic

Stochastic

20%

0%

NaturalIncidence

Resp

onse

BB

DoseDeterministic

Stochastic

20%

0%50mSv

NaturalIncidence

Resp

onse

BB

DoseDeterministic

Stochastic

20%

0%50mSv

NaturalIncidence

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Resp

onse

BB

LymphocyteDepression

DoseDeterministic

Stochastic

20%

0%50mSv 100mSv

NaturalIncidence

Resp

onse

BB

LymphocyteDepression Local

TissueEffects

DoseDeterministic

Stochastic

20%

0%50mSv 100mSv 1000mSv

NaturalIncidence

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Resp

onse

BB

LymphocyteDepression Local

TissueEffects

DoseDeterministic

Stochastic

20%

0%50mSv 100mSv

DeterministicEffects

1000mSv

NaturalIncidence

Resp

onse

BB

LymphocyteDepression Local

TissueEffects

StochasticEffects

DoseDeterministic

Stochastic

20%

0%50mSv 100mSv

DeterministicEffects

1000mSv

NaturalIncidence

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Resp

onse

BB

LymphocyteDepression Local

TissueEffects

StochasticEffects

Hormesis

DoseDeterministic

Stochastic

20%

0%50mSv 100mSv

DeterministicEffects

1000mSv

Hormesis

NaturalIncidence

Resp

onse

BB

LymphocyteDepression Local

TissueEffects

StochasticEffects

Hormesisdi l

DoseDeterministic

Stochastic

20%

0%50mSv 100mSv

DeterministicEffects

1000mSv

o es sMedical imaging

NaturalIncidence

ObjectivesRadiation Sources and IntensityRadiation Dose-Response RelationshipsALARA C di l P i i lALARA – Cardinal PrinciplesDeterministic/Stochastic Imaging Modalities (R&F, CT, DR)Imaging Economics

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ALARAAt Last Another Raise AlreadyAny Little Annoyance Requires AttentionAfter Love in the Afternoon Repeat AgainAfter Love in the Afternoon Repeat AgainAs Long as Repeating AllowsAs Low As Reasonably Achievable

Cardinal PrinciplesTimeDistanceShieldingShielding

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More Is Not Often Better…

When CT is the right exam:Child size the kVp and mAOne scan (single phase) is often enoughScan only the indicated area

ObjectivesRadiation Sources and IntensityRadiation Dose-Response RelationshipsALARA C di l P i i lALARA – Cardinal PrinciplesDeterministic/StochasticImaging Modalities (R&F, CT, DR)Imaging Economics

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DeterministicNon-LinearThresholdS it i ith dSeverity increases with dose

StochasticLinearNon-ThresholdI id i ith dIncidence increases with dose

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ObjectivesRadiation Sources and IntensityRadiation Dose-Response RelationshipsALARA C di l P i i lALARA – Cardinal PrinciplesDeterministic/Stochastic Imaging Modalities (R&F, CT, DR)Imaging Economics

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Frush – Strategies for Dose Reduction

Consider other modality: MRI, USLimit IV contrast phasesLimit scan rangeLimit scan rangeReduce mAReduce kVpMinimize use of pitch <1.0Consider shielding: thyroid, breast, gonadsUse tube current modulation

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Effective Dose

Radiography ….. 0.1 mSvNuclear Medicine ….. 1 mSv

Fluoroscopy ….. 5 mSvComputed Tomography ….. 10 mSv

ObjectivesRadiation Sources and IntensityRadiation Dose-Response RelationshipsALARA C di l P i i lALARA – Cardinal PrinciplesDeterministic/Stochastic Imaging Modalities (R&F, CT, DR)Imaging Economics

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Inflation……………….3%/yr

Healthcare…………....9%/yr

Medical Imaging........18%/yr

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ObjectivesRadiation Sources and IntensityRadiation Dose-Response RelationshipsALARA C di l P i i lALARA – Cardinal PrinciplesDeterministic/Stochastic Imaging Modalities (R&F, CT, DR)Imaging Economics

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