Dose quantities and units for radiation protection

Abstract

Absorbed dose, dose equivalent (ICRP) and equivalent dose (ICRU) are the basic physical quantities in the medical application of ionising radiation and for the radiation protection and safety work. In radiation protection, doses and dose rates are normally low, and the dose equivalent is considered to be correlated with the probability of cancer incidence during the rest of the person’s life. Only in exceptional cases, the dose is so high that cell killing and tissue damage occur, so-called deterministic (or tissue) effects. ICRP has also developed a specific dosimetric quantity, effective dose, that allows the exposure to whole-body as well as partial-body external radiation and from intake of radionuclides to be taken into account by one quantity, which is also designed to provide a correlation with risk of radiation-induced cancer. Neither the dose equivalent (equivalent dose) nor the effective dose can be measured directly. In the case of external exposure, they can be approximated by so-called operational quantities based on the equivalent dose. There are specific operational quantities developed for individual and workplace monitoring.