Radiation Safety

Safety of Radiation - Dosimetry

A dosimeter is a device used to monitor dosage of ionization radiation.

Film or thermoluminescent dosimeter badges give radiographers a way of determining the total radiation exposure for a period of time. Radiation exposed film turns black when it is developed. Plastic, aluminum, cadmium and/or lead filters in the holder for the film packet allow determination of types of radiation and its approximate energy. Lead filters out low energy radiation so that the film records only high energy radiation exposure under the lead filters. Plastic filters out most beta particles. Aluminum and cadmium filter out different energies of X-rays as well as beta particles. Cadmium converts neutrons into gamma radiation so that the neutron exposure may be measured. Unfortunately, film also detects heat and mechanical damage so the film dosimeters must be handled carefully.

National Dosimetry Services (NDS) offers dosimetry monitor services in Canada. This service is offered by Health Canada.

Thermoluminescent Dosimetry (TLD)

The thermoluminescent dosimeter badges contain small pieces of material such as lithium fluoride or manganese sulfate which absorb the radiation in such a fashion that some of the electrons in the material remain in excited or high energy states for a long time. When the thermoluminescent dosimeter materials are heated, they release light in quantities related to their radiation exposure. The materials can be reused, are relatively rugged and give reliable information over long periods of time. Also, the badges are generally smaller than film badges.

How Does Thermoluminescent Dosimetry Work gives an excellent description on the function of TLD.

Comparison of Dose Response in Fricke Dosimeters and Thermoluminescent Detectors describes how these devices work. Under construction!!!