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IONIZING RADIATION

IONIZING RADIATION. ….. a discussion of the health hazards associated with handling and use of materials capable of producing ionization of matter. Some basics of atomic theory…. Protons - Atomic particle found in an atom’s nucleus possessing a positive charge of +1

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IONIZING RADIATION

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  1. IONIZING RADIATION ….. a discussion of the health hazards associated with handling and use of materials capable of producing ionization of matter.

  2. Some basics of atomic theory….. • Protons - Atomic particle found in an atom’s nucleus possessing a positive charge of +1 • Electrons – Atomic particle possessing a negative charge (-1) • Neutrons – Atomic particle w/ no electric charge • Atomic weight – Sum of protons and neutrons in the nucleus of an atom • Atomic number – The number of protons in the nucleus of an atom • Isotopes – Nuclei of an element differing in atomic weight but having the same atomic number (e.g., U-235 vs U-238) • Radioactivity – The emission of energy in the form of alpha-, beta-, or gamma-radiation from then nucleus of an atom

  3. Radiation… • Radiation has no unique biological effects. • Concept of “half-life” • Time it takes for a radioisotope to lose half its strength

  4. Where is data gathered? • Early radiation workers • Medical personnel who routinely administer radiation for diagnosis or therapy • Patients treated with radiation • Workers who painted dials with luminous paints containing radium • Japanese atomic bomb survivors

  5. Where does it come from? • Natural, non man-made radiation accounts for more than half of the exposure we receive (rays from sun and stars, earthen materials, in food, etc.). • The biggest man-made contribution to radiation exposure of individuals results from the medical and dental use of x-rays and of radioactive materials to diagnose and treat disease.

  6. Ionizing vs Non-Ionizing • Ionizing radiation * • Radiation capable of producing ions • Comes from x-ray machines, nuclear reactors, and radioactive materials • Non-Ionizing radiation • Comes from microwaves, sound waves, light, lasers, radiofrequency, electromagnetic fields, etc.

  7. Forms of Ionizing Radiation • ALPHA • Travel only a short distance in air (~ 4” in air) • Stopped by dead skin, film of water, sheet of paper • Very hazardous when taken into the body • Avoid inhalation or ingestion • BETA • Penetrate human body to depth of 0.1-o.5” • Can penetrate wood to about 1.5” • Stopped by 0.5” aluminum or Plexiglas

  8. Forms of Ionizing Radiation (cont.) • GAMMA • Deep penetrating • Need steel, lead, etc. to shield • X –Radiation • Commonly thought of as electromagnetic radiation produced by an x-ray machine • Penetration depends on wavelength and material being irradiated. • Often use concrete to shield

  9. Penetrating Abilities • ALPHA - very limited ability; short range in air, stopped by skin • BETA - function of originating energy; can penetrate skin • GAMMA - highly penetrating; can reach all body organs

  10. Specific Ionization • ALPHA - large particle and short range --> high S.I. • BETA - lower S.I. • GAMMA - the lowest S.I. (ionization is a “secondary process” through electrons

  11. What occupations are at risk? • Healthcare/Medicine • Oncology • Radiation therapy • Dentistry • Researchers • Miners • Uranium, phosphate, etc. • Nuclear power plant employees

  12. Symptoms of Exposure • High level doses of radiation (generally doses of more than 100 rads), if received all at once, cause short-term effects that appear within hours, days, or weeks. Known as acute radiation syndrome • Initial symptoms: nausea, vomiting, and malaise. • After latent period: infections, fever, hemorrhage, loss of hair, diarrhea, loss of body fluid, CNS effects • >600 rads leads to death • Low level doses – risk is proportional to dose, but disagreement or uncertainty about exact responses.

  13. Adverse Effects • Cancer • Birth defects • Cataracts • Shortening of lifespan • If reproductive organs irradiated: • Genetic mutations may occur in sperm or egg cells

  14. Damage from Radiation • When radiation strikes a cell • It may pass through the cell without doing any damage • It may damage the cell, but the cell partially repairs the damage • It may damage the cell so that the cell not only fails to repair itself but reproduces in damaged form over a period of years • It may kill the cell

  15. Factors Determining Damage • Amount of radiation absorbed/penetrating ability • Amount of body area exposed • Energy of the radiation • Specific ionization associated with the radiation (how it damages/what it targets)

  16. Significant Considerations • If the radioactive source is outside the body, control strategies include 1) distance, 2) time, and 3) shielding. • If the radioactive source is inside the body, hazard is function of radiation type, energy, half-lives, radiosensitivity of tissues, etc., and control strategies must include all we know about controlling hazards.

  17. True or False? • Man-made sources of radiation, such as atomic weapons and x-rays have caused new diseases never encountered by medical science.

  18. True or False? • You can reduce the amount of radiation to which you are naturally exposed by living in a house made of brick, rather than wood.

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