There are several types of thermoluminescent dosimeters (TLD) badges used to detect radiation, depending on the type of operation being performed.
A whole body dosimeter badge is the most common and is always required, no matter what other type of dosimeter is worn. The whole body dosimeter must be clipped on the front of the body, below the shoulders and above the hips, and is always worn underneath any personnel protective equipment in use, especially lead aprons.
The collar dosimeter is worn on the collar and is required to determine exposures to the head and eyes, when a lead apron covers the whole body dosimeter. A neutron dosimeter is worn flat against the body's midsection, usually with a belt. A ring dosimeter is worn to determine radiation exposures to the hand and forearm, primarily in conjunction with fluoroscopy or for personnel who regularly handle radioactive materials.
A dosimeter must never leave the work area and should be stored with the area control badge when not in use. Personnel should never allow the TLD to be exposed to heat and sunlight, as this may affect the readings.
For personnel monitoring, Digital Alarm Dosimeters or DADs are used. These monitors have small ion chambers incorporated into them. They are usually required for personnel who work high radiation areas. The Digital Alarm Decimator should be used in conjunction with the TLD but never in lieu of the TLD. It is an important reminder that DADs and TLDs offer no protection for radiation exposures. They merely detect when how much exposure has occurred