DAP as a tool for analysis of

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DAP as a tool for analysis of

  1. 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. 2. • 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!
  3. 3. • 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 dose Effective dose ∑= T TT HwE .
  4. 4. • 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 0 20 40 60 80 100 120 140 160 180 A B C D E F1 F2 G H I DAP(Gy.cm²) 0 2 4 6 8 10 12 14 16 18 A B C D E F1 F2 G H E(mSv) From: L. Struelens, Optimisation of Patient Doses linked to Image Quality in Vascular Radiology, 2005 Effective dose for optimization?
  5. 5. 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
  6. 6. • 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 dose Effective dose simulation From: M. Zankl et al., Organ dose conversion coefficients for external photon irradiation of male and female voxel models, 2002
  7. 7. 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.)
  8. 8. • ICRP 103 publication (2007)  Sex averaging of organ doses DAP and effective dose Effective dose simulation From: ICRP Publication 103: The 2007 recommendations of the International Commission on Radiological Protection, 2007
  9. 9. 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
  10. 10. DAP and effective dose X-ray Characteristics for Imaging and Radioprotection Klaus Bacher Results
  11. 11. DAP and effective dose X-ray Characteristics for Imaging and Radioprotection Klaus Bacher Results
  12. 12. DAP and effective dose • Final report available on: www.fanc.fgov.be (section medische stralingsfysica/radiophysique médicale) Results
  13. 13. 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
  14. 14. 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
  15. 15. 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
  16. 16. DAP and maximum skin dose DAP as a tool for risk analysis Klaus 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
  17. 17. 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

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