Evaluation of radiation therapy for keloid using electron beam

Abstract

In radiation therapy for keloid, electron beams are delivered to the skin through a lead shield hollowed into the shape of the keloid. The shape of a postoperative keloid scar is linear, causing the irradiation shield to be long and narrow. This lead shield is put on the surface of the skin. Therefore, it is considered that beam data used in general external irradiation are not applicable to irradiation for keloid. Therefore, we used a water equivalent phantom and measured beam data by using chambers or film dosimeters. Experimental conditions were the same as those of actual radiotherapy for keloid. As a result of this procedure, the radiation technique was optimized. Electron energy and thickness of the bolus, thickness of the lead shield, margins such that the planning target volume would receive the necessary dose, and the method of MU calculation all were determined. It was suggested that these experiments were useful to establish the appropriate technique in irradiation for keloid.