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

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

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

The Numbers Game  How much is dangerous?  Deterministic/somatic effects  Stochastic effects

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

Quality Factors  Damage Coefficient  Relative Biological Effectiveness  Ave weighting factors Rad X QF = Rem  Gamma & X rays X 1  Beta X 1  AlphaX 20  NeutronsX 20

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

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

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

Symptoms of acute exposure  Onset within minutes to hours  Psychological effect  Blood Counts, lymph platelets  Gastro-Intestinal Synfdrome 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

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?

Dose Effect Models

The Odds  1 mRem of exposure ^ risk by 1 in 10 6  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 ft1 mRem/hr  Normal fatal CA incidence1 in 7

2007 Estimated US Cancer Deaths* ONS=Other nervous system. Source: American Cancer Society, Men 289,550 Women 270,100 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%

Bone Cancer  Radium Dial Painters c  First epidemiological study linking radioactive material to cancer  Discovered by high incidence of anemia and bone cancers of the jaw

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.

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

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

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

Fetal Effects of Radiation  Embryonic death  Teratogen  Mutagen  Carcinogen

Fetal Rat Study  400 Rad during gestation LD 50/30

Growth Stunting  days gestation