DAP as a tool for analysis of effective dose and maximum skin dose:

finalised and current projects

Klaus Bacher

Ghent UniversityDepartment of Basic Medical Sciences

Patient Dosimetry in Radiology, Management Center Europe, June 26 2010

• Easy online measurement of patient radiation exposure• Quantity is directly used for:

Definition of diagnostic reference levels (DRLs) Optimization

Dose area product (DAP)

• Possible use of DAP for further (risk) analysis: Stochastic effects: correlation with effective dose Deterministic effects: correlation with maximum skin

dose

not straightforward!

• Weighted sum of equivalent organ doses HT

• Risk-related quantity (not for individual risk assessment!)• Comparison of risks of different imaging modalities is possible

• No in vivo measurement possible• To be calculated/simulated according to ICRP 103 publication

(2007)

DAP and effective doseEffective dose

T

TT HwE .

• Intercomparisons of different procedures: same DAP in different X-ray procedures same effective dose

• Intercomparisons within a specific procedure: lower DAP in specific X-ray procedure lower effective dose

DAP and effective dose

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A B C D E F1 F2 G H I

DA

P (G

y.cm

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A B C D E F1 F2 G H

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From: L. Struelens, Optimisation of Patient Doses linked to Image Quality in Vascular Radiology, 2005

Effective dose for optimization?

DAP and effective dose

• Use of effective dose for further optimization, especially for interventional procedures→ need for accurate conversion coefficients based on DAP

• Project: DAP to effective dose conversion in cardiology and vascular/interventional radiology

Project supported by FANC

• ICRP 103 publication (2007) Taking into account the extended organ list (<-> ICRP 60) New organ weighting factors Use of reference voxelized computer model (<-> mathematical

models)

DAP and effective doseEffective dose simulation

From: M. Zankl et al., Organ dose conversion coefficients for external photon irradiation of male and female voxel models, 2002

DAP and effective dose

X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

Effective dose simulation

• Male and female reference voxel phantoms (Zankl et al.)

• ICRP 103 publication (2007) Sex averaging of organ doses

DAP and effective doseEffective dose simulation

From: ICRP Publication 103: The 2007 recommendations of the International Commission on Radiological Protection, 2007

DAP and effective dose

X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

• Simulations taking into account 12 projections for interventional cardiology procedures 20 projections for vascular/interventional radiology

procedures Different X-ray spectra (mm Al HVL)→ 256 DAP to effective dose conversion coefficients

Effective dose simulation

DAP and effective dose

X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

Results

DAP and effective dose

X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

Results

DAP and effective dose

• Final report available on: www.fanc.fgov.be (section medische stralingsfysica/radiophysique médicale)

Results

DAP and maximum skin dose

X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

• Multicenter study on skin doses of patients, treated with prolonged cardiological interventions (supported by FANC):

Skin dose measurements in 318 adult patients in 8 Belgian hospitals

Investigation of correlation of maximum skin dose with DAP

Belgian multi-centre study (2005)

From: E. Bogaert et al., Multicenter study on skin doses of patients, treated with prolonged cardiological interventions, 2005

DAP and maximum skin dose

X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

• Multicenter study on skin doses of patients, treated with prolonged cardiological interventions:

Identification maximum skin doses

Belgian multi-centre study (2005)

From: E. Bogaert et al., Multicenter study on skin doses of patients, treated with prolonged cardiological interventions, 2005

DAP and maximum skin dose

X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

• Multicenter study on skin doses of patients, treated with prolonged cardiological interventions:

Investigation of correlation of maximum skin dose with DAP→ establishing “trigger levels”

Belgian multi-centre study (2005)

From: E. Bogaert et al., A large-scale multicentre study of patient skin doses in interventional cardiology: dose-area product action levels and dose reference levels, 2009

DAP and maximum skin dose

DAP as a tool for risk analysisKlaus Bacher

• 2005 project: DAP trigger levels for cardiological interventions→ need for DAP trigger levels in other interventional procedures

• Current project: Determination of trigger levels for patient doses for interventional procedures (TRIR)

Project supported by FANC

DAP and maximum skin dose

• Measurements of skin dose distribution and maximum skin dose in 12 hosptitals and for different procedures: Radiofrequency (RF) ablations Transjugular Intrahepatic Portosystemic Shunt (TIPS) Chemo embolizations of the liver Cerebral embolizations Embolizations of vena spermatica Creation or treatment of AV fistula for hemodialysis Endoscopic retrograde cholangiopancreaticography (ERCP) Biliary drainages

• End of measurements: june 2010• Final report by july 2010

X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

Project supported by FANC