SHIELDING SMALL-FIELD HIGH-ENERGY ELECTRON-BEAMS IN CANCER-TREATMENT

The purpose of this study was to find an effective material that can be prepared quickly and easily prior to small-held electron-beam treatments so that lesions of the head and neck can be treated with minimal irradiation of the surrounding healthy tissue. Conventional preparation of custom anatomical prosthetic radiation shields, which are usually metal alloy masks, has been time-consuming and uncomfortable for the patients. New materials, made from light-body Reprosil(TM) (L. L. Caulk) filled with fine metal powder consisting of 70% Ag-30% Cu alloy, can be made by blending 90% (w/w) metal powder with 10% polysiloxane base and adding the polymerization catalyst separately. These combinations were mixed to form comfortably fitted shielding composites of different thicknesses. The electron-beam attenuation properties of slabs of this material were studied by irradiating calibrated radiochromic him (GafChromic(TM)) dosimeters behind different thicknesses of composite samples with small-held 13-, 15- and 18-MeV electron beams from a therapeutic linear accelerator. The results showed that this material can suitably attenuate high-energy electron beams when used in reasonable thicknesses.