Method of calculating side scatter factor for diagnostic X-rays

When computing the amount of leakage from a diagnostic X-ray room, the amount of scattered radiation released from the irradiated body in the lateral direction must be evaluated correctly. The side-scatter factor varies owing to change in the area and/or shape of the field, but the amount of variation is not always linearly proportional to the area of the field. Because the X-ray spectrum depends on the total filtration of the X-ray tube even if the irradiation geometry, X-ray equipment, and tube potential are the same, the side-scatter factor, too, is subject to change. In this paper, we propose a new method of calculation that uses the differential side-scatter factor computed by means of a Monte Carlo simulation, for obtaining the side-scatter factor of diagnostic X-rays. This method, which can calculate the side-scatter factor under any conditions of irradiation, is useful in evaluating the side-scatter factor of diagnostic X-rays. (author)