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Radiation Dose Limits for Adult Subjects

Radiation Dose Limits for Adult Subjects. Henry D. Royal, M.D. Associate Director Division of Nuclear Medicine Mallinckrodt Institute of Radiology Professor of Radiology Washington University School of Medicine St. Louis, MO. FDA Meeting 11/16/04. Past and Present Experiences.

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Radiation Dose Limits for Adult Subjects

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  1. Radiation Dose Limits for Adult Subjects Henry D. Royal, M.D. Associate Director Division of Nuclear Medicine Mallinckrodt Institute of Radiology Professor of Radiology Washington University School of Medicine St. Louis, MO FDA Meeting 11/16/04

  2. Past and Present Experiences • IAEA International Chernobyl Project • Several NAS Committees • Presidential Advisory Committee on Human Radiation Experiments • Immediate Past President, SNM • Veterans Advisory Committee for Environmental Hazards • Board of Directors, NCRP • US Delegate to UNSCEAR

  3. Overview • Current Regulations • Limitations of Current Regulations • Communicating Risks • Answers to Questions • Other Comments

  4. Whole Body, Active Blood-forming Organs, Lens Of The Eye, And Gonads:

  5. Limitations • Linked to Occupational Exposure • Whole Body Dose • No Adjustment for Age • No Adjustment for Life Expectancy

  6. Linked to Occupational Exposure • Rationale Unclear • Since Subjects Will Not Directly Benefit From RDRC Studies, Risk Should be Minimal • Unfortunately, Minimal Risk is Ambiguously Defined

  7. Whole Body Dose • Should Be Replaced By ED • Dose is a Surrogate for Risk • Dose Limits Should Be Modified To Adjust For Age And Life Expectancy

  8. Females Consumer Products Cancers per 104 Person-Gy Age BEIR V 1990

  9. Latent Period Exposure Cancer Rate Baseline Cancer Rate 0 20 40 60 80 Age (Years)

  10. Communicating Risks The Magnitude of a Risk Depends on Framing Common Approach: Radiation Increases the Risk of a Fatal Cancer by 4%-5% per Sievert (100 rems)

  11. Communicating Risks For a 5 Rem ED Participation In this Research Study Will Increase Your Chances of Getting Cancer (Dying) by 2/1000

  12. What’s Wrong With This Approach? • Very Difficult For Most People to Think in Terms of Numerical Risks • Does Not Distinguish Between Immediate Deaths and Delayed Deaths • Does Not Account for Age or Life Expectancy

  13. An Alternative ApproachDays of Life Lost • 2/1000 Times 15 Years = 10.95 Days

  14. Cologne et al: Lancet 2000; 356:303-07 >

  15. Loss of Life < 1 Gy – 2 Months >1 Gy – 2.6 Years 60% Cancer 30% Other 10% Leukemia Cologne et al: Lancet 2000; 356:303-07

  16. Catalog of Risks 6,000 5,000 4,000 Loss of Life Expentancy (Days) 3,000 Grade School Drop-Out 20% Overweight 2,000 Motor Vehicle Accidents 1,000 Orpahned Smoking - Male Poor Social Status Heart Disease High Risk Job Alcoholic Poverty Cancer Cohen: Health Physics 61:317-335, 1991

  17. Catalog of Risks 300 250 200 Loss of Life Expentancy (Days) 150 Energy Conservation 100 Spouse Smoking Radiation Worker Motor Vehicle Accidents Drinking Water Pesticides Radon Natural Hazards Fire, Burns Drowning 50 Poison Air Pollution Bicycles Small Cars Murder Alcohol Suicide AIDS Cohen: Health Physics 61:317-335, 1991

  18. An Alternative Approach • Variations in Background Radiation ±100 mrem X 70 Years = 7 rem • Not Possible to Measure the Risk Directly • “…the possibility that there may be no risks from exposures comparable to external natural background radiation can not be ruled out.” BEIR V 1990 Page 181

  19. Unintended Consequences • Some Populations Will Not Benefit From Medical Research • Increased Collective Dose to Obtain the Same Information • Opportunity Costs

  20. Answers to Questions • Current Dose Limits (5 Rem Annual Dose) Are Appropriate • Should Adjust for Age and Life Expectancy So That Dose is A Better Surrogate For Risk

  21. Other Comments • Get Rid of Organ Doses • Accounted for in ED • Should be Limited Out of Concern for Deterministic Effects Only • Keep Regulations Are Simple • Avoid Unintended Consequences

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