dosiometer

A dosiometer, more commonly called a dosimeter, is a device used to measure the absorbed dose of ionizing radiation received by a material or person. Dosiometers can be passive, recording dose over a period for later readout, or active, providing real-time dose measurements. The operating principle varies by type: film badges rely on changes in photographic film, thermoluminescent dosimeters (TLDs) store energy in a crystal lattice and release light when heated, optically stimulated luminescence (OSL) dosimeters use light to read stored energy, and electronic or semiconductor dosimeters measure charge collection or ionization current for immediate results.

Dosiometry is used in occupational safety, medical radiology and radiotherapy, nuclear power, space research, and environmental monitoring. Personal dosimetry tracks an individual’s exposure, while area dosimetry monitors ambient dose rates. Calibration against national standards and traceability to metrology institutes are essential to ensure accuracy and comparability across systems.

Common units associated with dosimetry are the gray (Gy) for absorbed dose and the sievert (Sv) for dose equivalent, with dosimeters typically reporting in millisieverts (mSv) for occupational exposure. Each type of dosimeter has specific advantages: film and TLDs are passive and require processing, OSL dosimeters enable relatively quick readouts, and electronic dosimeters provide real-time feedback and alarms.

Historically, film-based dosimetry emerged in the early 20th century, followed by the development of TLDs in the mid-20th century and OS L technology later, expanding the range of options for monitoring radiation doses in various settings.