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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.