dosimeters

Dosimeters are devices used to measure exposure to ionizing radiation and to record the accumulated dose received by a person or object over time. They support radiation protection by providing data for compliance with safety limits and for risk assessment. The measurement is typically reported as absorbed dose in grays (Gy) or as equivalent and effective dose in sieverts (Sv), depending on the radiation type and regulatory context.

Two broad classes exist: passive dosimeters, which do not require power and are read out after exposure, and active (electronic) dosimeters, which provide real-time readings and alarms. Passive dosimeters include film badges, thermoluminescent dosimeters (TLDs) that store energy and emit light when heated, and optically stimulated luminescent dosimeters (OSLDs) that emit light when stimulated by a laser. Pocket ionization chambers also serve as quick, on-the-spot indicators. Active dosimeters, such as electronic personal dosimeters, continuously monitor dose rate and accumulate dose, often with audible or visual alerts for high exposure.

Dosimeters are typically worn at the collar or chest to approximate eye and thyroid doses or other critical organs, and are calibrated against national standards. Regular maintenance, calibration, and recordkeeping are required by radiation protection regulations. Occupational dose limits vary by jurisdiction but generally restrict annual exposure to a safe level, with separate limits for whole-body, eye, and extremity doses.

Standards bodies and regulators, including ICRP, NCRP, and IEC/ISO committees, provide guidance for calibration, performance, and reporting. Dosimetry data underpin safety programs in medicine, industry, and research by documenting exposure history and informing protection measures.