dosimetrie

Dosimetry is the science of measuring and assessing ionizing radiation doses absorbed by matter, with emphasis on human tissue. It supports radiation protection, medical diagnosis and therapy by quantifying exposure and guiding dose optimization. Medical dosimetry involves planning and verification of dose delivery in radiology and radiotherapy, while environmental and occupational dosimetry monitor exposures in workplaces and the broader environment.

The fundamental physical quantity is absorbed dose, expressed in grays (Gy), representing energy deposited per unit mass. For health risk assessment, absorbed dose is converted to equivalent dose (sieverts, Sv) by radiation weighting factors, and to effective dose by accounting for tissue sensitivities. Operational quantities used in monitoring include ambient dose equivalent H*(10) and personal dose equivalent Hp(d).

Measurement methods employ personal dosimeters, including thermoluminescent dosimeters (TLDs), optically stimulated luminescence (OSL) devices, film badges, and electronic personal dosimeters. Internal dosimetry estimates doses from ingested or inhaled radionuclides through bioassays and biokinetic models, using urine, feces and imaging data to infer organ doses.

Dosimetry relies on calibration and standards from bodies such as the ICRU and ICRP. Dose measurements are traceable to national standards, with quality assurance and uncertainty analysis essential for reliability. Computational methods, including Monte Carlo simulations, are increasingly used to model dose distributions in complex geometries and to support treatment planning.

Applications span occupational protection in medical, nuclear, and research facilities; patient dose verification in imaging and radiotherapy; environmental monitoring and emergency response. Ongoing developments aim to improve sensitivity, reduce uncertainties, and enable real-time dose monitoring, while expanding Monte Carlo-based dosimetry and personalized treatment planning.