Radiation Safety Training for User’s

1. Radiation Safety Training for User’s Elayna Mellas Radiation Safety Officer Environmental Health & Safety Manager Clarkson University Downtown Snell 155 Tel: 315-268-6640 emellas@clarkson.edu This training course has been partially adapted from slides provided by Steve Backurz, Radiation Safety Officer of The University of New Hampshire

2. Table of Contents

3. Introduction • Radiation and radioactive materials are valuable tools used in research at Clarkson • Radio-labeling of biological materials • Sealed sources in chemistry/engineering • X-ray diffraction analysis of samples for chemistry and engineering research • Radioactive materials and X-ray machines are very safe if used properly and simple precautions are followed

4. Nucleus • Contains protons and neutrons • Small Size • Relatively large mass • Extremely large density • Large amount of stored energy • Orbiting Electrons • Large size • Low density • Orbit nucleus near speed of light • Small amount of energy relative to nucleus • Responsible for chemical bonds Review of Atomic Structure

5. "X" = Element Symbol "Z" = # Protons Each element has a unique "Z” "N” = # Neutrons Atomic Mass # = "A" "A" = Z + N = # Protons + # Neutrons Isotope: same Z, different N, thus different A Nomenclature for Elements A X Z

6. 15 Protons 17 Neutrons A = 32 Z = 15 32 P 15 Phosphorous-32 Atom

7. Definition: A collection of unstable atoms that undergo spontaneous transformation that result in new elements. • An atom with an unstable nucleus will “decay” until it becomes a stable atom, emitting radiation as it decays • Sometimes a substance undergoes several radioactive decays before it reaches a stable state • The “amount” of radioactivity (called activity) is given by the number of nuclear decays that occur per unit time (decays per minute). Radioactivity ("Activity")

8. A unit of activity defined by the number of radioactive decays from a gram of radium • 1Curie (Ci) = 2.22 E12 disintegrations/minute (dpm) • Sub-multiples of the Curie: • millicurie 1 mCi = 2.22 E9 dpm • microcurie 1 uCi = 2.22 E6 dpm • nanocurie 1 nCi = 2,220 dpm • picocurie 1 pCi = 2.2 dpm • Typical activities at Clarkson are in the Ci to mCi range The Curie

9. Disintegrations per minute (dpm) • Disintegrations per second (dps) • The SI unit for activity is the becquerel (Bq) • 1 Bq = 1 disintegration/second • 1 Curie (Ci) = 3.7 E10 Bq or 37 GBq • 1 millicurie = 37 MBq • 1 microcurie = 37 kBq Other Units of Measure

10. Any atom or molecule with an imbalance in electrical charge is called an ion • In an electrically neutral atom or molecule, the number of electrons equals the number of protons • Ions are very chemically unstable, and will seek electrical neutrality by reacting with other atoms or molecules Ion

11. Definition: Energy in the form of particles or waves • Types of Radiation • Ionizing: removes electrons from atoms • Particulate (alphas and betas) • Waves (gamma and X-rays) • Non-ionizing (electromagnetic): can't remove electrons from atoms • infrared, visible, microwaves, radar, radio waves, lasers Radiation

12. Radiation Wavelength in Angstrom Units 8 6 4 2 -2 -4 -6 10 10 10 10 1 10 10 10 Radio Infrared V Ultra-Violet X-Rays Cosmic Rays i Light s i b l Photon Energy in Million Electron Volts (MeV) e Gamma Rays 4 - 10 -8 -6 -4 -2 2 2 2 10 10 10 10 10 1 10 10 The Electromagnetic Spectrum

13. Alpha particles • High mass (4 amu) = 2 protons + 2 neutrons • High charge (+2) • High linear energy transfer (cause great biological damage) • Travel a few centimeters in air • Stopped by a sheet of paper or protective layer of skin • Not an external hazard • Concern would be for ingestion or inhalation Alpha Particles

14. Low mass (0.0005 amu) • Low charge - can be positively or negatively charged (+/- 1) • Travel 10 - 20 feet in air • Stopped by a book • Shield betas with low density materials such as lucite or plexiglass • Shielding high energy betas like P-32 with lead can generate more radiation than it shields due to Bremsstrahlung X-rays Beta Particles

15. Wave type of radiation - non-particulate • Photons that originate from the nucleus of unstable atoms • No mass and no charge • Travel many feet in air • Lead or steel used as shielding Gamma Radiation

16. 1 + 1  - n p Beta Minus Decay: 0 0 1 + 1  p n Beta Plus Decay: + 1 0 0 1 4 A-4 A +  Y Alpha Decay: X Z-2 2 Z Review of Nuclear Decay

17. 32 32 Beta Minus Decay: (neutron-excess nuclides) -  P S + Examples of Nuclear Decay 16 15 0 22 22 +  Beta Plus Decay: (neutron-deficient nuclides) Na + Ne 0 11 10 206 4 210  Alpha Decay: (Heavy nuclides above atomic number 82) Pb + Po 2 84 82

18. 93.5% 0.514 MeV  - 137 Cs 6.5% 137m Ba 55 0.662 MeV  56 1.176 MeV - 137 Ba 56 • A decay scheme is a graphical representation of radioactive decay • Depicts the parent/daughter relationship • Branching fractions and energy levels are shown Decay Scheme

19. Decay Law: 140 120 100 t A(t) = A(0) * e 80 A(o) = Initial Activity A(t) = Activity after time "t" t = Decay time λ = constant = 0.693 / t1/2 t 1/2 = half-life Activity (curies) 60 40 20 0 0 14 28 42 56 70 84 98 Time (days) • Half life: The time required to reduce the amount of a particular type of radioactive material by one-half • Example: 120 Ci of P-32 (t 1/2 = 14 days) Decay Law & Half-Life

20. Wave type of radiation - non-particulate • Photons originating from the electron cloud • Same properties as gamma rays relative to mass, charge, distance traveled, and shielding • Characteristic X-rays are generated when electrons fall from higher to lower energy electron shells • Discrete energy depending on the shell energy level of the atom • Bremsstrahlung X-rays are created when electrons or beta particles slow down in the vicinity of a nucleus • Produced in a broad spectrum of energies • Reason you shield betas with low density material X-Rays

21. Energy is lost by the incoming charged particle through a radiative mechanism Bremsstrahlung Radiation Beta Particle Bremsstrahlung Photon - + + Nucleus

22. High Voltage Power Supply Current Tungsten Filament Target Cathode Anode Glass Envelope Tube Housing X-Ray Machine Components

23. kVp - how penetrating the X-rays are • Mammography - 20 - 30 kVp • Dental - 70 - 90 kVp • Chest - 110 - 120 kVp • mA - how much radiation is produced • Time - how long the machine is on • Combination of the above determines exposure X-Ray Machine Basics

24. Mass (amu) Charge Travel Distance in Air Types of Radiation 4.0000 Alpha +2 few centimeters Beta Plus 0.0005 +1 few meters few meters Beta Minus 0.0005 -1 Gamma 0.0000 0 many meters 0.0000 X-Rays 0 many meters Neutron 1.0000 0 many meters

25. Radiation: Energy in the form of particles and waves • Radioactive Material: Material that is unstable and emits radiation • Contamination: Radioactive material where it is not wanted • Campfire example: burning logs (radioactive material), heat (radiation), burning embers that escape the controlled area (contamination) Radiation, Radioactive Material, and Contamination

26. Radiation deposits small amounts of energy, or "heat" in matter • alters atoms • changes molecules • damage cells & DNA • similar effects may occur from chemicals • Much of the resulting damage is from the production of ion pairs Interaction of Radiation with Matter

27. - - Alpha Particle + - electron is stripped from atom + The neutral atom gains a + charge = an ion - Ionization The process by which a neutral atom acquires a positive or negative charge

28. Ionization by a Beta particle: Ionization - ejected electron Beta Particle - - - Colliding Coulombic Fields The neutral absorber atom acquires a positive charge -

29. Gamma interactions differ from charged particle Interactions • Interactions called "cataclysmic" - infrequent but when they occur lot of energy transferred • Three possibilities: • May pass through - no interaction • May interact, lose energy & change direction (Compton effect) • May transfer all its energy & disappear (photoelectric effect) Gamma Interactions

30. An incident photon interacts with an orbital electron to produce a recoil electron and a scattered photon of energy less than the incident photon Compton Effect Before interaction After interaction Scattered Photon - - - - - - - - Electron is ejected from atom Incoming photon Collides with electron

31. Biological Effects of Radiation

32. Large Doses Received in a Short Time Period • Accidents • Nuclear War • Cancer Therapy • Short Term Effects (Acute Radiation Syndrome 150 to 350 rad Whole Body) Anorexia Nausea Erythema Fatigue Vomiting Hemorrhage Epilation Diarrhea Mortality Acute Exposure

33. Absorbed Dose (Rads) Effect 10,000 Death in a few hours 1,200 Death within days 600 Death within weeks 450 LD 50/30 100 Probable Recovery 50 No observable effect 25 Blood changes definite 5 1st Blood change obs Effects of Acute Whole Body Exposure on Man

34. Doses Received over Long Periods • Background Radiation Exposure • Occupational Radiation Exposure • 50 rem acute vs 50 rem chronic • acute: no time for cell repair • chronic: time for cell repair • Average US will receive 20 - 30 rem lifetime • Long Term Effects • Increased Risk of Cancer • 0.07% per rem lifetime exposure • Normal Risk: 30% (cancer incidence) Chronic Exposure

35. Cellular Effects • Ionization within body tissues: similar to water • Ionization causes many derivatives to be formed: • Peroxides • Free Radicals • Oxides • These compounds are unstable and are damaging to the chemical balance of the cell. Various effects on cell enzymes and and structures occur. • Radiation is not the only insult responsible • Pollutants • Vitamin imbalance (poor diet) • Sickness and Disease

36. Cells often recover from damage • Repeated Insults may cause damage to be permanent • Cell Death • Cell Dysfunction - tumors, cancer, cataracts, blood disorders • Mitosis (Cell Division) Delayed or Stopped • Chromosomal breaks • Organ Dysfunction at High Acute Doses Cellular Effects (con't)

37. Wide variation in the radiosensitivity of various species • Plants/microrganisms vs. mammals • Wide variation among cell types • Cells which divide are more sensitive • Non-differentiated cells are more sensitive • Highly differentiated cells (like nerve cells) are less sensitive Variations in Sensitivity

38. The fetus consists of rapidly dividing cells • Dividing cells are more sensitive to radiation effects than nondividing cells • Effects of low level radiation are difficult to measure • A lower dose limit is used for the fetus Effects on the Fetus

39. It is possible to damage the hereditary material in a cell nucleus by external influences like Ionizing radiation, chemicals, etc. • Effects that occur as a result of exposure to a hazard while in-utero are calledteratogenic effects • Teratogenic effects are thought to be more severe during weeks 8-17 of pregnancy - the period of formation of the body’s organs • A higher incidence of mental retardation was found among children irradiated in-utero during the bombings of Hiroshima and Nagasaki Genetic Effects

40. Smoking General Babies weigh 5-9 oz. Less than average < 1 pack/day Infant Death 1 in 5 > 1 pack/day Infant Death 1 in 3 Alcohol 2 drinks/day Babies weigh 2-6 oz. Less than average 1 in 10 2-4 drinks/day Fetal alcohol syndrome 1 in 3 > 4 drinks/day Fetal alcohol syndrome 1 in 3 to 1 in 2 Radiation 1 rem Childhood leukemia deaths before 12 years 1 in 3333 1 rem Other childhood cancer deaths 1 in 3571 Statistically, a radiation exposure of 1 rem poses much lower risks for a woman than smoking tobacco or drinking alcohol during pregnancy Maternal Factors & Pregnancy

41. Acute effects Chronic effects? Effects occur after a threshold Effects occur at any level = stochastic Biological effects Dose Dose The stochastic model is more conservative, and is used to establish dose limits for occupational exposure Dose Response Curves

42. Most important factor in determining when effects will occur • Recovery is less likely with higher dose rates than lower dose rates for an equivalent amount of dose = more permanent damage • More recovery occurs between intermittent exposures = less permanent damage Rate of Absorption

43. The larger the portion - the more damage (if all other factors are the same) • Blood forming organs are more sensitive • A whole body dose causes more damage than a localized dose (such as in medical therapy). • Dose limits take this into consideration Area Exposed

44. Radiation Exposure & Dose

45. Your exposure to radiation can never be zero because background radiation is always present • Natural Sources - Radon • Cosmic • Terrestrial • Technologically Enhanced Sources (Man-Made) • Healing Arts: Diagnostic X-rays, Radiopharmaceuticals • Nuclear Weapons Tests fallout • Industrial Activities • Research • Consumer Products • Miscellaneous: Air Travel, Transportation of Radioactive Material Background Exposure

46. Total exposure Man-made sources Medical X-Rays Radon 55.0% 11 Other 1% Internal 11% Consumer Products 3% Man-Made 18% Nuclear Medicine 4% Cosmic 8% Terrestrial 6% Total US average dose equivalent = 360 mrem/year Annual Dose from Background Radiation

47. 2 x 10 particles (mostly protons) per second are incident on the atmosphere • Energy greater than one BILLION ELECTRON VOLTS • Interact with atoms in the atmosphere and produce secondary particles • muons, electrons, photons, and neutrons • responsible for cosmic dose 18 Cosmic Radiation

48. Major sources • Potassium - a few grams per 100 grams of ground material • Thorium and Uranium - a few grams per 1,000,000 grams of ground material • Dose due mainly to photons originating near the surface of the ground Terrestrial

49. Naturally occurring radioactive gas • Second leading cause of lung cancer • Estimated 14,000 deaths per year • Easy to test for • short and long term tests available • EPA guideline is 4 pCi/L • Fixable • Radon in water from drilled wells can also be an entry method Radon

50. Q (charge) X = M (mass of air) • A measure of the ionization produced by X or Gamma Radiation in air • Unit of exposure is the Roentgen Exposure, X