Radiation

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Beta Particles: High speed electron ejected from nucleus; -1 charge, light 0.00055 AMU; Typical Energy = several KeV to 5 MeV; Range approx. 12'/MeV in air, a few mm in tissue; Low LET (QF=1) causing light damage (6-8 ion pairs/µm in tissue). Primarily an internal hazard, but high beta can be an external hazard to skin. In addition, the high speed electrons may lose energy in the form of X-rays when they quickly decelerate upon striking a heavy material. This is called Bremsstralung (or Breaking) Radiation. Aluminum and other light (<14) materials are used for shielding.

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Gamma Rays

Gamma Rays (or photons): Result when the nucleus releases energy, usually after an alpha, beta or positron transition

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X-Rays

X-Rays: Occur whenever an inner shell orbital electron is removed and rearrangement of the atomic electrons results with the release of the elements characteristic X-Ray energy

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X- and Gamma Rays: X-rays are photons (Electromagnetic radiations) emitted from electron orbits. Gamma rays are photons emitted from the nucleus, often as part of radioactive decay. Gamma rays typically have higher energy (Mev's) than X-rays (KeV's), but both are unlimited.

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Neutrons

Neutrons: Have the same mass as protons but are uncharged

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QUANTIFICATION OF RADIATION

A. Quantifying Radioactive Decay

B. Quantifying Exposure and Dose

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A. Quantifying Radioactive Decay

Measurement of Activity in disintegrations per second (dps);

1 Becquerel (Bq) = 1 dps;

1 Curie (Ci) = 3.7 x 1010 dps;

Activity of substances are expressed as activity per weight or volume (e.g., Bq/gm or Ci/l).

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B. Quantifying Exposure and Dose

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. Instruments often measure exposure rate in mR/hr.