Radiation

Radiation as relevant to Medcicne

1. radiation

2. Radiation is an energy in the form of electro-magnetic waves or particulate matter, traveling in the air.”

3. 1895 - Wilhem Conrad Roentgen discovered X-rays and in 1901 he received the first Nobel Prize for physics. 1903 - Marie Curie and Pierre Curie, along with Henri Becquerel were awarded the Nobel Prize in physics for their contributions to understanding radioactivity, including the properties of uranium. 1942 - Enrico Fermi and others started the first sustained nuclear chain reaction in a laboratory beneath the University of Chicago football stadium. 1945 – Nuclear bombs dropped on Japan. History

4. Radiation Sources

5. Sources of radiation can be divided into two categories: Natural Background Radiation Man-Made Radiation

6. Natural Background Radiation Cosmic Radiation Terrestrial Radiation Internal Radiation

7. Cosmic Radiation The earth, and all living things on it, are constantly bombarded by radiation from outer space Charged particles from the sun and stars interact with the earth’s atmosphere and magnetic field to produce a shower of radiation . The amount of cosmic radiation varies in different parts of the world due to differences in elevation and to the effects of the earth’s magnetic field . 35 mrad / yr normal altitude Jet pilots – 300 mrad / yr

8. Atmospheric Radiation Terrestrial Radioactive material is also found throughout nature in soil, water, and vegetation. Important radioactive elements include uranium, thorium, radium & isotopes of potassium(K 40 ) Some radioactive material is ingested with food and water. The amount of terrestrial radiation aprox . 50 mrad / yr Atmospheric Gases like Radon & thorum – 2 mrad / yr

9. Internal Radiation People are exposed to radiation from radioactive material inside their bodies. Besides radon, the most important internal radioactive element is naturally occurring potassium-40. Others - uranium, thorium, strontium & carbon. 25 mrad / yr. May go up to 70 or 80. Total natural radiation - 0.1 rad / yr.

10. Man-Made Radiation Sources Examples of man-made sources of radiation to members of the public: Lantern mantles Medical diagnosis Building materials Nuclear power plants Coal power plants Tobacco Phosphate fertilizers T V sets Radium watches

11. Annual Average Dose (mrem/year) man-made source

12. Nuclear fall out Fallout  is the residual radioactive material propelled into the upper atmosphere following a  nuclear blast Carbon C 14 , iodine I 131 , cescium Cs 137 & strontium Sc 90 The Chernobyl disaster was a nuclear reactor accident in the Chernobyl Nuclear Power Plant in the Soviet Union on 26 April 1986.

13. Radiation Ionizing Radiation Higher energy electromagnetic waves (gamma) or heavy particles (beta and alpha). High enough energy to pull electron from orbit. Non-ionizing Radiation Lower energy electromagnetic waves. Not enough energy to pull electron from orbit, but can excite the electron.

14. Electromagnetic Spectrum 10 -14 10 -12 10 -10 10 -8 10 -6 10 -4 10 -2 1 10 2 10 4 10 6 10 8 Wavelength in Meters 10 10 10 8 10 6 10 4 10 2 1 10 -2 10 -4 10 -6 10 -8 10 -10 10 -12 10 -14 Broadcast Short wave TV FM Radar Infrared Near Far Visible Ultraviolet X Rays Gamma Rays Cosmic Rays Power Transmission Ionizing Radiation Nonionizing Radiation Energy - Electron Volts High Low

15. Non-ionizing Radiation

16. Definition: “ They are electromagnetic waves incapable of producing ions while passing through matter, due to their lower energy .” Sources Ultraviolet light Visible light Infrared radiation Microwaves Radio & TV Power transmission

17. Nonionizing Examples Ultraviolet – Black light – induce fluorescence in some materials Vision – very small portion that animals use to process visual information Heat – infrared – a little beyond the red spectrum Radio waves – beyond infrared Micro waves Electrical power transmission – 60 cycles per second with a wave length of 1 to 2 million meters.

18. Ionizing Radiation

19. Ionizing Radiation D efinition “ It is a type of radiation that is able to disrupt atoms and molecules on which they pass through, giving rise to ions and free radicals”. Sources – x-rays, radioactive material produce alpha, beta, and gamma radiation, cosmic rays from the sun and space.

20. Ionizing Radiation Paper Wood Concrete Alpha Beta Gamma Energy Low Medium High

21. Radioactive Material Either natural or created in nuclear reactor or accelerator Radioactive material is unstable and emits energy in order to return to a more stable state (particles or gamma-rays) Half-life – time for radioactive material to decay by one-half

22. Alpha Particles Two neutrons and two protons Charge of +2 Emitted from nucleus of radioactive atoms Transfer energy in very short distances (10 cm in air) Shielded by paper or layer of skin Primary hazard from internal exposure Alpha emitters can accumulate in tissue (bone, kidney, liver, lung, spleen) causing local damage

23. Beta Particles Small electrically charged particles similar to electrons Charge of -1 Ejected from nuclei of radioactive atoms Emitted with various kinetic energies Shielded by wood, body penetration 0.2 to 1.3 cm depending on energy Can cause skin burns or be an internal hazard of ingested

24. Gamma-rays Electromagnetic photons or radiation (identical to x-rays except for source) Emitted from nucleus of radioactive atoms – spontaneous emission Emitted with kinetic energy related to radioactive source Highly penetrating – extensive shielding required Serious external radiation hazard

25. X-rays Overlap with gamma-rays Electromagnetic photons or radiation Produced when electrons strike a target material inside and x-ray tube Emitted with various energies & wavelengths Highly penetrating – extensive shielding required External radiation hazard

26. Radiation Units Exposure: Roentgen 1 Roentgen (R) = amount of X or gamma radiation that produces ionization resulting in 1 electrostatic unit of charge in 1 cm3 of dry air . Absorbed Dose : rad (Roentgen absorbed dose) = absorption of 100 ergs of energy from any radiation in 1 gram of any material ; 1 Gray ( Gy ) = 100 rads = 1 Joule/kg; Exposure to 1 Roentgen approximates 0.9 rad in air. Biologically Equivalent Dose : Rem (Roentgen equivalent man) = dose in rads x QF , where QF = quality factor. 1 Sievert ( Sv ) = 100 rems .

27. SI Unit for radiation exposure Coulombs/kilogram (C/Kg) 1 Roentgen = 2.58 X 10^-4 C/Kg SI unit for absorbed dose Gray ( Gy ) 1 Gy =100 Rad SI Unit for activity Becquerel ( Bq ) = 1 disintegration/ second Curie ( Ci ) = 3.7 X 10^10 disintegrations/ second

28. Biological effects

29. Acute Effects 0-25 No observable effect. 25-50 Minor temporary blood changes. 50-100 Possible nausea and vomiting and reduced WBC. 150-300 Increased severity of above and diarrhea, malaise, loss of appetite. 300-500 Increased severity of above and hemorrhaging, depilation. Death may occur > 500 Symptoms appear immediately, then death has to occur .

30. Delayed Somatic Effects : Delayed effects to exposed person include: Cancer, leukemia, cataracts, life shortening from organ failure, and abortion. Probability of an effect is proportional to dose (no threshold). Severity is independent of dose. Doubling dose for cancer is approximately 10-100 rems . Genetic Effects : Genetic effects to off-spring of exposed persons are irreversible and nearly always harmful. Doubling dose for mutation rate is approximately 50-80 rems . (Spontaneous mutation rate is approx. 10-100 mutations per million population per generation.)

31. Dose Response Tissue Examples of tissue Sensitivity Very High White blood cells (bone marrow) Intestinal epithelium Reproductive cells High Optic lens epithelium Esophageal epithelium Mucous membranes Medium Brain – Glial cells Lung, kidney, liver, thyroid, pancreatic epithelium Low Mature red blood cells Muscle cells Mature bone and cartilage

32. Organ Specific Skin Erythema – desquamation (reversible) Hair loss Mucous Membranes Fibrin Plaquing Urinary and Bladder Changes Visceral Changes (secretory) Reproductive Organs Irreversible damage to gametes Sterility Bone Suppress osteoblast activity Decrease number of osteocytes

33. Permissible dose from man made < 5 rad/ yr X- ray greatest hazard – 4 rad in one minute standards

34. Radiation protection

35. Time Reduce the spent near the source of radiation. Distance Increase the distance from the source of radiation. Shielding Place shielding material between you and the source of radiation. Reducing Exposure

36. Monitoring Personal Dosimeters: Provide a record of accumulated exposure for an individual worker over extended periods of time and are small enough for measuring localized exposures Common types: Film badges; pocket dosimeters, & Thermoluminescence detectors (TLD );

37. Direct Reading Survey Meters and Counters : Useful in identifying source of exposures and in evaluating potential sources, such as surface or sample contamination, source leakage, inadequate decontamination procedures, background radiation. Common types:   Alpha  Proportional or Scintillation counters Beta, gamma  Geiger-Mueller or Proportional counters X-ray, Gamma  Ionization chambers Neutrons  Proportional counters

38. Continuous Monitors : Continuous direct reading ionization detectors (same detectors as above) can provide read-out and/or alarm to monitor hazardous locations and alert workers to leakage, thereby preventing exposures . Long-Term Samplers : Used to measure average exposures over a longer time period. For example, charcoal canisters or electrets are set out for days to months to measure radon in basements (should be <4 pCi /L).