Individualized Compensating Filters and Dose Optimization in Pelvic Irradiation

Abstract

A method is presented for design and construction of individualized, shaped, tapered split-field blocks for external beam use in combined brachytherapy and teletherapy of pelvic malignancies. Coronal plane implant calculations and a block-making device are needed. The physician specifies the total split-field dose and the radiation to supplement areas of insufficient brachytherapy. A hot wire cuts styrofoam slabs of appropriate thickness to conform to isodose zones from implant calculations. Cerrobend® alloy, the attenuating material, is cast into the spaces and the block is positioned in accordance with portal and implant radiographs. Thermoluminescent dosimetry confirms the method.