What are Dosimeters Used For?

A dosimeter is an instrument used to measure exposure to ionizing radiation, such as alpha or beta particles, neutrons, gamma rays, or X-rays. It is used in a science called dosimetry and is a record of the radiation dose received. Modern electronic personal dosimeters can provide a continuous reading of the cumulative dose and the current dose rate, and can warn the user with an audible alarm when a specified dose rate or cumulative dose is exceeded. Other dosimeters, such as thermoluminescent or film types, require post-use processing to reveal the cumulative dose received, and cannot give a current dose indication while in use.

Metal-oxide semiconductor field-effect transistor dosimeters are now used as clinical dosimeters for radiation therapy radiation beams. The ion chamber dosimeter, like the thermoluminescent one, is reusable, but it is automatically read to immediately determine exposure. At the end of the month or quarter, dosimeters should be returned to Radiation Safety as soon as possible to expedite processing.

Commonly used routine dosimeters include poly (methyl methacrylate) (PMMA) or plexiglass, radiochromic, cellulose triacetate (CTA) films, cericcerous dosimeters, and ECB. In addition to whole-body monitoring, they are small enough that they can be mounted not only on finger rings or wrist dosimeters, but they can even be attached to the fingertips and covered with gloves. The results of prior personal monitoring can be used as an indication, noting that the external radiation dose to the fetus is unlikely to exceed 25% of the personal dosimeter measurement (ICRP, 2000).

For dosimetry, the most common base material is lithium fluoride (LiF) with certain impurities that determine its properties in detail. Regarding the risk of developing cataracts, the dose equivalent to the lens of the eye is estimated as Hp (0.0), read from the neck or head dosimeter, corrected by the attenuation of the glasses. This is an actual reading obtained from an ambient dose gamma monitor or personal dosimeter. Prior to use by the user, a dosimeter is charged to a high voltage, causing the fiber to deflect due to electrostatic repulsion.

Personnel dosimeters are devices used by laboratory personnel to monitor radiation doses from external sources. The most commonly used reference dosimeters include the Fricke, ceric—waxy, dichromate, ethanol—monochlorobenzene (ECB) and alanine dosimeters. For electron irradiation, the graphite calorimeter is the main or reference dosimeter, while the CTA film is widely used as a routine dosimeter. Such devices are known as legal dosimeters if they have been approved for use in personnel dose recording for regulatory purposes.

It can also be obtained from the reading of a single dosimeter placed outside the platform, using a different factor. Like thermoluminescence dosimeters (TLD) and optically stimulated luminescence (OSLD) dosimeters, alanine granules can be used for dosimetry verification in accredited dosimetry laboratories.