New Dose Limits for the Lens of the Eye Implications and Implementation Industrial Radiography

Transcription

1 New Dose Limits for the Lens of the Eye Implications and Implementation Industrial Radiography ISEMIR WGIR Richard VAN SONSBEEK 1, John C. LE HERON 2, Gonzague ABELA 3, Francisco C.A. DA SILVA 4, Razak HAMZAH 5, Thomas A. LEVEY 6, Matthias PURSCHKE 7, Kamal SAHAIMI 8, Christian LEFAURE 9 1 Applus RTD; richard.vansonsbeek@applusrtd.com 2 International Atomic Energy Agency, Vienna, Austria; J.Le.heron@iaea.org 3 EDF; Saint Denis, France; gonzague.abela@edf.fr 4 Institute of Radiation Protection and Dosimetry; Rio de Janeiro, Brazil; dasilva@ird.gov.br 5 Malaysia Nuclear Agency; Kajang, Malaysia; Razak_hamzah@nuclearmalaysia.gov.my 6 Acuren Group Inc.; Edmonton, Canada; tlevey@acuren.com 7 German Society for Non-Destructive Testing (DGZfP); Berlin, Germany; pm@dgzfp.de 8 CNESTEN, Rabat, Morocco, sahaimi@cnesten.org.ma 9 consultant; Paris, France; clefaureconsult@free.fr International Atomic Energy Agency

2 Industrial Radiography A method of Non-Destructive Testing Radiation sources: Radioactive sources X-ray tubes Linear accelerators Location: Shielded enclosures / Radiation Bunkers In the field / on the customer' s site

3 Gamma Radiography Exposure Device

4 Radioactive sources Energy and Thickness

5 Radioactive Sources Activities and Dose Rates

6 X-ray Radiography Equipment Typical specification: 300 kvp 6 ma Dosisrate (@ 1 m) 6 tot 20 Sv/h

7 Background to ISEMIR Information System on Occupational Exposure in Medicine, Industry & Research There are some areas in medicine, industry and research where radiation uses can lead to significant occupational exposures Both in normal operations and in accident situations But detailed information at the operational level is lacking

8 ISEMIR the launch January 2009, for an initial 3 year period, to help improve occupational radiation protection in targeted areas 2 Working Groups, initially Interventional Cardiology, commenced Feb 2009 Industrial Radiography, commenced Jan 2010

9 Working Group Industrial Radiography (WGIR) From left to right: Christian Lefaure, Francisco Da Silva, Kamal Sahaimi, Gonzague Abela, Richard van Sonsbeek, Matthias Purschke, A. Razak Hamzah, John Le Heron (Thomas Levey is not on the picture) 10/8/2012 9

10 Objectives of the efforts of WGIR Supporting the Industry in keeping ALARA: 1. the dose due to normal exposure if normal exposure is justified! 2. the risk of exposure due to accidents (risk: combination of chance and consequence) 10/8/

11 Site Radiography Gamma Radiography Typical Stages during Normal Exposure 1. Storage of gamma source in storage facility 2. Movement of gamma source from store to vehicle 3. Transport of gamma source in vehicle to field location / client site 4. Movement of gamma source from vehicle to work site 5. Exposure(s) (after set up of equipment a) Wind-out (gamma source in guide tube) b) Exposure (gamma source in collimator) c) Wind-in (gamma source in guide tube) 6. Movement of gamma source from work site to vehicle 7. Transport of gamma source in vehicle to store 8. Movement of gamma source from vehicle to store 9. Go to 1. 11

12 When using databases on individual doses, be aware that in general we are comparing Apples with Pears 12

13 Differences in average dose per person Relatively high(er) dose Relatively low(er) dose Single disciplinary technicians (RT) Multi disciplinary technicians (RT, UT,.) Only RT technicians included Non RT technicians included High workload (# films, # hours) Low workload (# films, # hours) Mobile radiography (less shielding) Fixed Radiography (more shielding) Thick objects tested Thin objects tested High source strength Low source strength High production requirement Low production requirement Exposure due to accident Normal exposure 13

14 Dose distribution The radiographer data are for 234 radiographers, the NDT company data are for nearly 3500 radiographers, and the regulatory body data are for over 16,000 radiographers Average dose Radiographer data: 3.4 msv RB data: 2.9 msv 2% of radiographers in 2009 Effective doses > 20 msv Causes? 10/8/

15 Dose versus workload No correlation found Radiation protection in industrial radiography is not being effectively optimized Mean occupational dose per radiographic exposure 4.8 ± 2.3 μsv for all operators 2.9 ± 1.2 μsv for operators with workload > 100 exposures No effect on dose per exposure found with: level of NDT training type of sources being used, activity of sources, use of collimation, or incidence of events But limited data numbers 10/8/

16 Eye Lens Dose Industrial Radiography Not monitored No information available

17 New Dose Limits for the Lens of the Eye Implications for Normal Exposures Current consensus of WGIR for Normal Exposures during Industrial Radiography (After reading SSK report Monitoring the Eye Lens Dose ) No need for additional monitoring Body is exposed uniformly (large distance to source) Effective Dose is a good estimate for Eye Lens Dose No need for additional protective measures Eye Lens Dose would obviously also benefit from Dose Constraints / Action Levels put on Effective Dose

18 New Dose Limits for the Lens of the Eye Implications for Accidental Exposures General Accident Scenarios Source not retrieved in shielded position Observed (proper survey) or not (improper survey) Source is lost at worksite Source is rupted Effective dose probably not good estimate Shorter distances between source and body No uniform exposure of body Higher exposure to eye lens very likely

19 New Dose Limits for the Lens of the Eye Implications for Accidental Exposures Additional monitoring and protective measures in case of radiation incidents? Emergency preparedness and response Emergency equipment / tools Reconstruction of Eye Lens Dose in case of radiation accidents? Is there any real benefit?

20 Thank you! 10/8/