Rachel Lane August 26, 2014 15:30-17:00 RGN 3248

1. Rachel LaneAugust 26, 201415:30-17:00RGN 3248 Applications: Epidemiology, Radiation and Health Department of Epidemiology and Community Medicine Faculty of Medicine University of Ottawa

2. Question 1 Ionizing radiation and cancer in professions such as aircrew and healthcare workers Radiation protection of aircrew exposed to cosmic radiation and patients exposed to thoracic imaging procedures

3. The principles of radiological protection: Justification, Optimisation of Protection and Application of Dose Limits Linear no-threshold (LNT) assumption for radiation protection purposes (around 5% per Sv) Occupational dose limit: 20 mSv/year Public dose limit: 1 mSv/year Doses should be kept “as low as reasonably achievable” (ALARA principle) taking into account economic and social factors International System of Radiological Protection (ICRP 60, 1991)

4. Sources and Distribution of Average Radiation Exposure to the World Population WHO, 2014 http://www.who.int/ionizing_radiation/env/en/

5. Radiation Risk Models CNSC, 2013: http://www.nuclearsafety.gc.ca/eng/resources/health/linear-non-threshold-model/index.cfm

6. Cosmic Radiation Exposures in Aircrew Cosmic Radiation: Altitude, Latitude (geomagnetic latitude effect), Flight Time In 1991, the International Commission on Radiological Protection Publication 60 (1991) identified airline flight crew as an occupational exposed group Justification, Optimisation, Dose Limits Natural background: 2.4 mSv/year Public dose limit: 1 mSv/year Occupational dose limit: 20 mSv/year Aircrew can receive low doses from cosmic radiation at levels similar to radiation-exposed occupational groups a range of 0-6 mSv per year cumulative exposures of ~ 80 mSv in a career

7. Aircrew: Health Effects of Radiation Lower rates of all-cause mortality, overall cancer, and lung cancer compared to the general population (healthy worker effect) Increased rates of female breast cancer and malignant melanoma compared to the general population Indication of increased brain cancer among pilots and prostate and leukemia among aircrew compared to the general population These excesses are not likely related to cosmic radiation but may be due to circadian rhythm, reproductive factors, lifestyle and other risk factors.

8. Do Aircrew Need Radiation Protection? Yes! Regulatory: 1996 European Commission has developed and implemented regulations to protect their aircrew Voluntary: Transport Canada have guidance measures for managing aircrew’s exposure to cosmic radiation, and aircrew are monitored and dose records are recorded, however; they are currently not regulated in Canada With increases in air travel, planes flying at greater altitudes and over longer distances, transpolar routes, and changes in fuselage materials, radiation protection regulations and dose monitoring of aircrew is crucial

9. Medical Workers: Health Effects of Radiation British radiologists, US radiologic technologists, and medical diagnostic workers in China exposed to X-rays < 1950: radiation equipment was less sophisticated and radiation protection less stringent so occupational radiation exposures were higher (~ 50 mGy) Elevated risk of leukaemia, breast cancer and melanoma and nonmelanoma skin cancers and circulatory disease and eye cataracts > 1950: improvements in radiation technology and stringent radiation protection resulted in consistent decreasing occupational radiation exposures No evidence of an increase in cancer or non-cancer mortality

10. Breakdown of Annual Doses by Job Category for all of Canada, 2007 2007 Preliminary Analysis: National Dose Registry, 2007

11. Estimated Annual Collective Effective Dose of Ionizing Radiation due to Diagnostic Medical Examinations, 1997-2007 (Adapted from (3), Table 4 of IV. Scientific Report to GA)

12. Trend in Radiation Exposure from Diagnostic Radiology (Adapted from (3), Table 2 of IV. Scientific Report to GA)

13. High Doses from Medical Imaging and Widespread Use Pose Public Health Cancer Risk • Medical exposures largest artificial source of radiation (98%) and is growing at a remarkable rate • Between 1980 and 2006, the annual per-capita effective radiation dose in the United States nearly doubled • Almost all of this increased dose came from exposure through medical imaging (especially CT), which increased by about 600 percent • CT scans give extremely detailed images doses per procedure can be 50-500 times greater dose than standard X-rays and can range from 1.5 - >25 mSv • Multiple procedures can quickly be at levels of observed cancer effects • Patients are not regulated (Figure adapted from Mettler et al., Radiology 253(2), 2009)

14. Do Patients Need Radiation Protection? Yes! 2006 Ontario Health Technology Advisory Committee (OHTAC ) 2007 Recommendations Report of the Diagnostic Imaging Committee for Computed Tomography 2012 ICRP Publication 105 focusing on radiological protection in medicine was published which consolidates the current advice OHTAC Recommendations General CT Recommendations Create CT Radiation Safety Committee Healing Arts Radiation Protection Act/Regs (CT) CT Scatter Testing and Inspections Radiation Dose Reduction Recommendations Develop best practices Collect and analyse radiation dose information across Ontario Diagnostic Reference Levels (UK and US) Guidelines for patient shielding Develop training program for CT medical staff

15. Radiation Risk and Protection in Perspective • Patients • Justification • Optimization • Reference Levels • Workers • Justification • Optimization • Dose Limits

16. Thank you!