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

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!

DAP and effective dose Effective dose 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)

Effective dose for optimization? DAP and effective dose Effective dose 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

Project supported by FANC 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

Effective dose simulation DAP and effective dose Effective dose 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

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

Effective dose simulation DAP and effective dose Effective dose 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

Effective dose simulation DAP and effective dose Effective dose 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

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

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

DAP and effective dose Results Final report available on: www.fanc.fgov.be (section medische stralingsfysica/radiophysique médicale)

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

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

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

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 analysis Klaus Bacher

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