Radiation Protection Basics

1. Radiation Protection Basics http://www.ansto.gov.au/__data/assets/image/0005/8762/Training_DSC_0114.jpg

2. Internal Dose • Routes of entry • Inhalation • Ingestion • Percutaneous (skin absorption) • Wounds (through openings in skin) • Bioassay: measurement of radioisotope burden • Products for sampling: urine, nail clippings, sweat, exhaled air, hair, etc. • In vivo: various whole body scanners

3. A snapshot • Radioisotope burden at time of measurement is just that. • Actual amount of radioactivity at time of uptake will be greater • Decay • Excretion • Chemical form of radioisotope is important • Especially, whether soluble or insoluble

4. Fate of contaminants • Insoluble • If inhaled, trapped in mucus layer • Eventually shuttled to GI tract • Particle size, pulmonary rates important • Pass through GI tract if ingested. • Soluble • Evenly dispersed through body fluid, or • Seeks specific organ (testis, thyroid, colon) • Seeks bone

5. Kinetics of soluble contaminants • Body fluids • Filtered by kidneys • Exponential decrease in concentration • Organ uptake • Rapidly cleared with sizeable portion take up by organ • Slower, long term release from organ • Bone uptake • Much slower turnover, long term deposition

6. Uptake of commonly used radioisotopes • Note: levels of interest range from organ system down to molecular • Tritium (3H) • Readily exchangeable element • Absorbed through skin, enters total body fluid • Limits on how much can be used before bioassay is required; urine samples • 14C • Critical organ: fat tissue (high C concentration?) • Entry depends on chemical form

7. continued • 32P, 33P • 20% of ingested or inhaled soluble isotope taken up by bone. Lungs and GI tract also affected, depending on route of entry. • Rapidly dividing cells incorporate isotope into nucleic acids, long retention. • 35S • Entry depending on exposure • Testis most at risk

8. continued • 125I, 131I • Sizeable amount absorbed by thyroid gland. • Iodine isotopes are gamma emitters • Work with Iodine usually requires monitoring by thyroid scan. • 51Cr • Used in immunology research • Excreted through GI tract, so accumulated and concentrated there.

9. Terms related to dose calculations • Effective dose • Like rem calculations, except in addition to the radiation type getting a fudge factor, the target organ gets one also. • The rem x the organ sensitivity factor, all added to get a whole body equivalent dose. • Committed dose • Dose received from an intake, calculated on the basis of 50 years (70 for children or members of public)

10. Basic Tenets of Radiation Safety • ALARA • As Low As Reasonably Achievable • Reflects uncertainty re dangers of low dose radiation. • All work to be carried out in ways that minimize dose as much as possible without huge inconvenience or expense.

11. The 3 Guiding Principlesof Radiation protection • Shielding • Know the radiation you are working with; choose a barrier that is suitable. • Lead for gammas, wax for neutrons; avoid lead for high energy betas • Time • The less time you spend in a radiation field, the lower your dose. • Distance • The inverse square rule: intensity = 1/r2 The farther you are away, the lower your dose.

12. Rules reflect concerns • Danger: internal contamination • Radioisotopes used in biological research seldom irradiate much, so internal exposure bigger problem • NO EATING, DRINKING, SMOKING or applying of cosmetics. All actions that potentially produce internal exposures. • Loss of Control • Careful record keeping • Frequent swipe tests, surveys • Locking of doors, challenging the unauthorized

13. Emergency actions • 1. health is first • 2. cordon off area • 3. maintain constant monitoring • 4. contact RSO- he makes further decisions on calling ADH, instructing on cleanup. http://www.georgetown.edu/gumc/ehs/chemsafe/images/spill.gifhttp://www.worldprayer.org.uk/images/user/Footsteps%20web1.gif

14. Regulatory Issues • Society’s changing views and historical events • Pre-1945: Drinks & baths in radium salts for health • 1945: Boom; 1950’s mutants in the movies • 1960’s: counterculture + industry arrogance + earthquake zones in California, epicenter of counterculture. “The Atom and the Fault”- good reading • March 1979: Three Mile Island, Pennsylvania • April 1986: Chernobyl, the Ukraine • September 11, 2001: Terrorist attack on NYC • Increasing fear, so increased regulatory pressure

15. Who’s in charge? • Nuclear Regulatory Commission (NRC) • Reports to Congress • Oversees programs of “agreement states” • Oversees nuclear power industry and governement research facilities. • Agreement states • Make up their own rules, within NRC guidelines • Administer their own programs • 34 out of 50 currently • Arkansas is an agreement state

16. Who’s in charge-2 • Arkansas Department of Health (ADH) • Not as reasonable as in the past • The BIG YELLOW BOOK • Rules and Regulations for Control of Sources of Ionizing Radiation” • Universities, hospitals, industries • Issue a license to use and possess radioactive materials • On campus: the Radiation Safety Committee

17. The License • The license spells out our responsibilities as an institution • We spell out how we will meet the requirements specified by ADH • We get to write the license (within certain guidelines), but we are held explicitly to it! • Examples: how much radioactive material we will have on hand, who gets to use it, how we will police its use and check for contamination, etc.

18. Radiation Safety Manual • Mostly for benefit of faculty and staff • Shows ADH that we are in control of program • Lists a variety of useful information • Summary of state regulations • License requirements • Administrative structures • General practices and requirements • Online: • http://ehc.astate.edu/Radiation.htm

19. To use radioactivity on campus • Provide proof of training • Specific requests for isotope and amounts • Clearly described experimental procedures • So committee can evaluate safety • Promise to be in compliance with all rules, regulations, and procedures • Includes records of receipt, use, disposal, wipe tests.

20. The biggest issue on campus:Control of material Safety obviously important, but danger posed by isotopes used on campus is minimal.