In 1973, International Commission on Radiological Protection Publication 22 recommended that the acceptability of radiation exposure levels for a given activity should be determined by a process of cost–benefit analysis. It was felt that this approach could be used to underpin both the principle of ALARA as well for justification purposes. The net benefit, B, of an operation involving irradiation was regarded as equal to the difference between its gross benefit, V, and the sum of three components; the basic production cost associated with the operation, P; the cost of achieving the selected level of protection, X; and the cost Y of the detriment involved in the operation: B = V - (P + X + Y). This article presents a theoretical cost–risk–benefit analysis that is applicable to the diagnostic accuracy (Levels 1 and 2) of the hierarchical efficacy model presented by National Council on Radiation Protection and Measurements in 1992. This enables the costs of an examination to be related to the sensitivity and specificity of an X-ray examination within a defined clinical problem setting and introduces both false-positive/false-negative diagnostic outcomes into the patient radiation protection framework.