Dosimeter

A dosimeter is a device that measures exposure to ionizing radiation. It is used to assess the absorbed dose or dose equivalent received by a person or object, and to ensure that exposure remains within prescribed limits.

Most dosimeters are passive devices worn by individuals or installed for area monitoring. Passive types include film dosimeters, thermoluminescent dosimeters (TLDs), and optically stimulated luminescence (OSL) dosimeters. Active or electronic dosimeters provide real-time readings, such as electronic personal dosimeters (EPDs) or solid-state detectors.

Operation and readings vary by type. Film dosimeters rely on changes in photographic film after exposure, requiring chemical processing to read the dose. TLDs use crystals that store energy from radiation and emit light when heated, with light yield proportional to dose. OSL dosimeters use light to release stored energy from luminescent centers. Electronic dosimeters measure ionization current or diode response and display dose in real time.

Units commonly used are the gray (Gy) for absorbed dose and the sievert (Sv) for dose equivalent, which accounts for radiation type and tissue sensitivity. Readings are typically calibrated to national or international standards. Applications include occupational monitoring in healthcare, nuclear facilities, and research, patient dosimetry in radiology, and environmental or area monitoring, including aviation exposure.

Calibration and regulation: Dosimeters are traceable to national or international standards, requiring periodic calibration and maintenance. Worn or installed devices must be replaced or recalibrated according to manufacturer guidance and regulatory requirements. Exposure data are recorded and retained for compliance and dose management.