Quality factor and dose equivalent in radiation protection.

Abstract

In considering the present state of radiation units for protection purposes, we shall start from proposals made by the International Commission on Radiation Units and Measurements. In ICRU Report 11 (ICRU, 1968), and again in Report 19 (ICRU, 1971), dose equivalent is defined as the product of absorbed dose, quality factor, and any other necessary modifying factors, at the point of interest in tissue. However, the quality factor is not denned, apart from indicating its dependence on linear energy transfer, and there is an apparent uncertainty relating to the dimensions of the dose equivalent. Criticism of the definitions has already appeared from some quarters. As members of the British Committee on Radiation Units and Measurements, we have discussed these issues at considerable length and come to conclusions which, while not supporting some of the criticisms made, should clarify the position.