Stochastic late effects after partial body irradiation in diagnostic radiology: evaluation for approximate data.

The paper describes a method to estimate the risk of inducing a malignant disease by the highly nonuniform partial body X-irradiation as performed in diagnostic radiological examinations. The cumulative probability, p, for the development of a radiation-induced malignant neoplasm is obtained from the equation p = Gt Es, where Es is the energy imparted to the soft tissues of trunk and head during a special radiological procedure. Gt is the mean integral incidence function for trunk and head, reflecting the cancer inducibility of organs and tissues in trunk and head, G t approximately 0;3 kJ-1; The value of Gt was obtained from mortality risk factors for the different tissues at risk, adopted in ICRP Publication 26, 1977. The energy, E, imparted to the body in typical radiographic procedures is in the range of 1--30 mJ, going up to about 1 J in an extensive fluoroscopic examination of the gastrointestinal tract. The corresponding values for p are about 10(-6) to 10(-5), in extensive examinations 10(-4). As to a radiograph of chest, the method described in this paper yields practically the same value for p as the Monte Carlo calculation, using the MIRD phantom and the relevant mortality risk factors.