health physics
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HEALTH PHYSICS
BY NADIA
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Health PhysicsHealth 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.
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IntroductionRadioactive material is a hazardous material.
Hazardous materials are managed safely every day. (i.e. gasoline; chlorine)
Radioactive materials are also safely managed daily.
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Radiation
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Electromagnetic Spectrum
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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
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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
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Radiation
Ionizing [Health Physics] Alpha Beta Gamma X-Rays Neutron
Non-Ionizing [Industrial Hygiene] microwave, radio, laser, etc.
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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
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X-Rays
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Types of Ionizing Radiation
Alpha ParticlesStopped by a sheet of paper
Beta ParticlesStopped by a layer of clothingor less than an inch of a substance
Gamma RaysStopped by inches to feet of concreteor less than an inch of lead
RadiationSource
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Properties of α, β, γ
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Radiation versus Contamination Radiation is a type of energy;
contamination is material Exposure to radiation will not
contaminate you
Radioactive contamination emits radiation
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Radiation and Radioactive Material
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Contamination
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Irradiation
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Activation/Induced Activity
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Physical Radionuclide Half-Life Activity Where Found
Cesium-137 30 y 1.5x106 Ci Food Irradiator
Cobalt-60 5 y 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 8 d 0.015 Ci Nuclear Medicine Technetium-99m 6 h 0.025 Ci Diagnostic Imaging
Americium-241 432 y 0.000005 Ci Smoke Detectors
Radon-222 4 d 1 pCi/l Environment
Examples of Radioactive Materials
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Personnel Dose Limits*Occupational Workers:
TEDE 5 rem/yr Lens of eye 15 rem/yr Extremities 50 rem/yr Skin 50 rem/yr Other organs 50 rem/yr
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Annual Exposure Limits
Whole Body = Total Effective Dose EquivalentGeneral Public Limit = 2 mrem / hr or 0.1 rem / yr
rem mrem
Whole-Body 5 5,000
Eye 15 15,000
Shallow 50 50,000
Minors & Declared Pregnant Workers*
10 % 10 %
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Radiological UnitsRadiation Exposure (rate) Measurement:
Roentgen or milliroentgen (R/h or mR/h)
rem or millirem (mrem/h) Sievert (SI unit), 1 sievert = 100 rem
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Radiological UnitsActivity Measurement:
Curie or milli or microCurie Becquerel (SI unit) or MBq Disintegrations per minute (dpm) Counts per minute (cpm)
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Half-Life
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Types of Radiation Hazards
External Exposure: whole-body partial-body
Contamination: External: radioactive
material on the skin
Internal: radioactive material inhaled, swallowed, absorbed through skin or wounds
ExternalExposure
InternalContamination External
Contamination
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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)
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Basic Radiation Safety Concepts
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ALARAA - As
L - Low
A - As
R - Reasonably
A - Achievable
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Recognition of Radiation Sources Labeling
Certain Certain exemptionsexemptions
Radiation detection
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StandardRadiation Protection
PrinciplesTime
Distance
Shielding
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Shielding Examples
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Biological EffectsPotential 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
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Detecting and Measuring Radiation Detectors or Survey Instruments:
contamination exposure rate
Personal Dosimeters – Film, TLD, Self-reading measure doses to responders
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Questions?Thank you.
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