MEDRADSC 2X03 Chapter Notes - Chapter 26: Inert Gas, Geiger Counter, Projectional Radiography
11 Sep 2017
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There are three general groups of dosimetry badges: film badges, thermoluminescent detectors (tlds, electronic dosimeters. Another way to measure radiactivity is with a geiger muller counter. These use a silver-halide film (similar to that used in plain film radiography). Advantages: cheap, can distinguish between different energies of photons, can measure doses from different types of radiation, provide a permanent record, accurate for exposures > 100 millirem. This is then measured to calculate the amount of radiation the dosimeter has been the tld is heated and visible light is released from the crystal in proportion to absorbed radiation exposed to. Calcium fluoride and lithium fluoride are commonly used. The tld must be used in its casing. As this applies filters to correct for deep. Calibration post-read-out is still required to correct for differential absorption. They are changed and read-out every 3 months. Advantages: can be made very small for finger/eye doses, can be reused.
