Published on March 3, 2014
HEALTH PHYSICS BY NADIA 1
Health Physics Health physics is the development, dissemination, and application of both the scientific knowledge of, and the practical means for radiation protection. The objective of health physics is the protection of people and the environment from unnecessary exposure to radiation. 2
Introduction Radioactive material is a hazardous material. Hazardous materials are managed safely every day. (i.e. gasoline; chlorine) Radioactive materials are also safely managed daily. 3
Electromagnetic Spectrum 5
Radiation and Radioactivity Radiation = emission and propagation of energy through space or through a material in the form of waves or, by extension, corpuscular emissions Radioactivity = spontaneous emission of radiation from the nucleus of an unstable atom 6
Electromagnetic Spectrum of Radiation Non-ionizing radiation = does not contain sufficient energy to produce ions Ionizing Radiation = particles or photons with sufficient energy to produce ions in the medium 7
Radiation Ionizing [Health Physics] Alpha Beta Gamma X-Rays Neutron Non-Ionizing [Industrial Hygiene] microwave, radio, laser, etc. 8
Ionizing Radiation • Ionizing radiation is radiation capable of imparting its energy to the body and causing chemical changes • Ionizing radiation is emitted by - Radioactive material - Some devices such as x-ray machines 9
Types of Ionizing Radiation Alpha Particles Stopped by a sheet of paper Radiation Source Beta Particles Stopped by a layer of clothing or less than an inch of a substance Gamma Rays Stopped by inches to feet of concrete or less than an inch of lead 11
Properties of α, β, γ 12
Radiation versus Contamination Radiation is a type of energy; contamination is material Exposure to radiation will not contaminate you Radioactive contamination emits radiation 13
Radiation and Radioactive Material 14
Activation/Induced Activity 17
Examples of Radioactive Materials Physical Radionuclide Half-Life Activity Where Found Cesium-137 30 y 1.5x106 Ci Food Irradiator Cobalt-60 5y 15,000 Ci Cancer Therapy Plutonium-239 24,000 y 600 Ci Nuclear Weapon Iridium-192 74 d 100 Ci Ind. Radiography Hydrogen-3 12 y 12 Ci Exit Signs Strontium-90 29 y 0.1 Ci Ocular Therapy Iodine-131 Technetium-99m 8d 6h Americium-241 432 y Radon-222 4d 0.015 Ci 0.025 Ci 0.000005 Ci 1 pCi/l Nuclear Medicine Diagnostic Imaging Smoke Detectors Environment 18
Personnel Dose Limits* Occupational Workers: TEDE Lens of eye Extremities Skin Other organs 5 rem/yr 15 rem/yr 50 rem/yr 50 rem/yr 50 rem/yr 20
Annual Exposure Limits rem mrem Whole-Body 5 5,000 Eye 15 15,000 Shallow 50 50,000 10 % 10 % Minors & Declared Pregnant Workers* Whole Body = Total Effective Dose Equivalent General Public Limit = 2 mrem / hr or 0.1 rem / yr 21
Radiological Units Radiation Exposure (rate) Measurement: Roentgen or milliroentgen mR/h) (R/h or rem or millirem (mrem/h) Sievert (SI unit), 1 sievert = 100 rem 22
Radiological Units Activity Measurement: Curie or milli or microCurie Becquerel (SI unit) or MBq Disintegrations per minute (dpm) Counts per minute (cpm) 23
Types of Radiation Hazards Internal Contamination External Exposure: whole-body partial-body External Contamination External Exposure Contamination: External: radioactive material on the skin Internal: radioactive material inhaled, swallowed, absorbed through skin or wounds 25
RADIATION AND PREGNANCY Time dependence first 2 weeks of pregnancy-resorption and termination of pregnancy 2nd week to 10th week period of major organogenesis=possible congenital abnormalities 2nd and 3rd trimesters, responses above are unlikely. Malignant disease during childhood a likely response. This also possible with exposure in 1st trimester Responses likely only with high rad doses (above 25 rad) 26
Basic Radiation Safety Concepts 27
ALARA A - As L - Low A - As R - Reasonably A - Achievable 28
Recognition of Radiation Sources Labeling Certain exemptions Radiation detection 29
Standard Radiation Protection Principles Time Distance Shielding 30
Shielding Examples 31
Biological Effects Potential effects on the human body from ionizing radiation: No damage Cells repair damage and operate normally Cells are damaged and operate abnormally Cells die as a result of the damage 32
Detecting and Measuring Radiation Detectors or Survey Instruments: contamination exposure rate Personal Dosimeters – Film, TLD, Self-reading measure doses to responders 33
Questions? Thank you. 34
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