Klaus Bacher Ghent University Department of Basic Medical Sciences

1. DAP as a tool for analysis of effective dose and maximum skin dose:finalised and current projects Klaus Bacher Ghent University Department of Basic Medical Sciences Patient Dosimetry in Radiology, Management Center Europe, June 26 2010

2. Dose area product (DAP) • Easy online measurement of patient radiation exposure • Quantity is directly used for: • Definition of diagnostic reference levels (DRLs) • Optimization • Possible use of DAP for further (risk) analysis: • Stochastic effects: correlation with effective dose • Deterministic effects: correlation with maximum skin dose •  not straightforward!

3. DAP and effective dose Effectivedose • 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)

4. DAP and effective dose Effectivedose for optimization? • 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 From: L. Struelens, Optimisation of Patient Doses linked to Image Quality in Vascular Radiology, 2005

5. DAP and effective dose Project supported by FANC • 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

6. DAP and effective dose Effectivedose simulation • 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) From: M. Zankl et al., Organ dose conversion coefficients for external photon irradiation of male and female voxel models, 2002

7. DAP and effective dose Effectivedose simulation • Male and female reference voxel phantoms (Zankl et al.) X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

8. DAP and effective dose Effectivedose simulation • ICRP 103 publication (2007) • Sex averaging of organ doses From: ICRP Publication 103: The 2007 recommendations of the International Commission on Radiological Protection, 2007

9. DAP and effective dose Effectivedose simulation • 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 X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

10. DAP and effective dose Results X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

11. DAP and effective dose Results X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

12. DAP and effective dose Results • Final report available on: www.fanc.fgov.be (section medischestralingsfysica/radiophysiquemédicale)

13. DAP and maximum skin dose Belgian multi-centre study (2005) • 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 From: E. Bogaert et al., Multicenter study on skin doses of patients, treated with prolonged cardiological interventions, 2005 X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

14. DAP and maximum skin dose Belgian multi-centre study (2005) • Multicenter study on skin doses of patients, treated with prolonged cardiological interventions: • Identification maximum skin doses From: E. Bogaert et al., Multicenter study on skin doses of patients, treated with prolonged cardiological interventions, 2005 X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

15. DAP and maximum skin dose Belgian multi-centre study (2005) • Multicenter study on skin doses of patients, treated with prolonged cardiological interventions: • Investigation of correlation of maximum skin dose with DAP • → establishing “trigger levels” 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 X-ray Characteristics for Imaging and Radioprotection Klaus Bacher

16. DAP and maximum skin dose Project supported by FANC • 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) DAP as a tool for risk analysisKlaus Bacher

17. DAP and maximum skin dose Project supported by FANC • 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