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Radiation & Health Risks

Radiation & Health Risks. Neal M. Boucher, CNMT, CSI(ML) Radiation Safety Officer Dartmouth Hitchcock Medical Center. History of Exposure. Pioneer Radiologists Atomic Bomb Survivors Radium Dial Painters Uranium Miners Medical Irradiation Animal Studies Criticality Accidents Chernobyl .

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Radiation & Health Risks

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  1. Radiation & Health Risks Neal M. Boucher, CNMT, CSI(ML) Radiation Safety Officer Dartmouth Hitchcock Medical Center

  2. History of Exposure • Pioneer Radiologists • Atomic Bomb Survivors • Radium Dial Painters • Uranium Miners • Medical Irradiation • Animal Studies • Criticality Accidents • Chernobyl

  3. We know more about Radiation & its effects than any other agent • Research tool • Medicine Dx & Rx • Military weapons • Industry precision gauges • Irradiator sterilizer • Accidents • The accumulated knowledge is immense

  4. Uncertainties • Natural Background • Other carcinogens, mutagens • Genetic predisposition • Thresholds • Precise dosimetry • Clean data • Adequate follow up • Long time lines • Other health issues

  5. The Numbers Game • How much is dangerous? • Deterministic/somatic effects • Stochastic effects

  6. Radiation Types & Origin • X-rays from atom outer shells • e- transitions • Gamma rays from nuclear decay • Higher E photons • Beta particles wide E range • e- and e+ ejections from nucleus • Alpha particles stripped He+2 • Very Energetic MeV short range

  7. Quality Factors • Damage Coefficient • Relative Biological Effectiveness • Ave weighting factors Rad X QF = Rem • Gamma & X rays X 1 • Beta X 1 • Alpha X 20 • Neutrons X 20

  8. Radiation Biology • Interaction with matter/tissue • Ionization path LET > free radicals • Absorption tolerance / Tissue sensitivity • Cell damage • No effect • Repairable damage, free radicals • Dysfunctional proteins, enzymes, hormones • Cell death by DNA or cellular function

  9. Radiation Biology • Genetic Effects • Somatic cells precancerous • Congenital defects during organogenesis • Stem cell disruption • Germ Cells • Cell Death early in Meiosis • Genetic defect passed on • Expression early, late, next generation • Dominant /recessive

  10. Deterministic Effects • LD50/30 (Lethal Dose 50%/30 days) • RAD/REM definition • WB systemic vs local irradiation • Acute vs chronic exposures • Minimum detectable response • GSD Genetically Significant Dose

  11. Symptoms of acute exposure • Onset within minutes to hours • Psychological effect • Blood Counts, lymph platelets • Gastro-Intestinal Synfdrome 300-500 Rad • Neuro-Vascular Syndrome >1000 Rad • Central Nervous Sys. shutdown 10,000 Rad • Untreated, aplastic anemia, infection 30 days 500 Rad LD 50/30 • Dermal effects if localized

  12. Low Level Cancer Induction • Where’s the data? • How does it translate to occupational exposures? • What are the odds compared to natural background radiation? • What impact does Medical exposure have? • What about longevity?

  13. Dose Effect Models

  14. The Odds • 1 mRem of exposure ^ risk by 1 in 106 • Natural Background (NH) 350 mRem • 1 Chest film PA & Lat 25 mRem • 1 CT Scan 3000 mRem • 1 Mammogram 10 mRem • Trans-Atlantic flight 35K ft 1 mRem/hr • Normal fatal CA incidence 1 in 7

  15. 2007 Estimated US Cancer Deaths* Men289,550 Women270,100 26% Lung & bronchus 15% Breast 10% Colon & rectum 6% Pancreas 6% Ovary 4% Leukemia 3% Non-Hodgkin lymphoma 3% Uterine corpus 2% Brain/ONS 2% Liver & intrahepatic bile duct 23% All other sites Lung & bronchus 31% Prostate 9% Colon & rectum 9% Pancreas 6% Leukemia 4% Liver & intrahepatic 4%bile duct Esophagus 4% Urinary bladder 3% Non-Hodgkin 3% lymphoma Kidney 3% All other sites 24% ONS=Other nervous system. Source: American Cancer Society, 2007.

  16. Bone Cancer • Radium Dial Painters c 1920-50 • First epidemiological study linking radioactive material to cancer • Discovered by high incidence of anemia and bone cancers of the jaw

  17. Leukemia • Most sensitive indicator • Only shows up statistically after large doses • Other Causes • Benzene, formaldehye • Chemo Rx alkylating agents • Downs Syn & other genetic disease • Human T-cell Virus & Myelodysplastic Dis.

  18. The Case of I-131 Therapy • First radionuclide widely used • Long history circa 1940 • Activity 30-200 mCi • WB dose 15 Rem • Thyroid dose 30-40,000 Rads • No increase in head & neck Ca’s subsequent to treatments • Why?

  19. I-131 fallout • Principal Fission fragment • Easily ingested and inhaled • Long half life @ 8.02 days • Food chain contaminant • Children and pregnant women vulnerable to thyroid uptake • Stable Iodine can block uptake • Widely debated public health issue

  20. Radiation Hormesis • European spas and natural springs • Uranium, Thorium, Radium, Radon Gas • Patent medicines prior to 1920 • Immune system stimulation @ 5 Rem • Diagnostic studies • Long Term studies of Survivors • Cancer statistics are less than expected

  21. Fetal Effects of Radiation • Embryonic death • Teratogen • Mutagen • Carcinogen

  22. Fetal Rat Study • 400 Rad during gestation LD 50/30

  23. 150 Rad @ 13 days gestation Growth Stunting

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