Comparative Study on the Surface Dose of Some Bolus Materials

Abstract

In order to investigate the possibility of using different materials as bolus in radiotherapy, five samples denoted by S2-S6 were prepared and analyzed by comparison with one available commercial bolus denoted by S1. Sample S1 was a thermoplastic material from Qfix; S2 was a moldable silicon rubber (RTV-530 from Prochima); S3 and S4 were obtained by adding micrometric particles of Al and Cu respectively (at the same mass concentration of 5.5%); S5 was another molda-ble silicon rubber (GSP400 from Prochima) and S6 was a mixture of GSP400 and micrometric particles of Cu (at the mass concentration of 5.5%). The measurements of normalized transmitted dose as a function of sample thickness were performed for all samples (S1-S6) at two values of electron beam energy (6 and 9 MeV) produced by a linear accelerator VARIAN 2100SC. The results showed that the maximum of the normalized transmitted dose of manufactured samples (S2-S6) is registered at smaller sample thicknesses than for the analyzed commercial bolus (sample S1). The smallest sample thickness corresponding to normalized maximum point dose is obtained for sample S2 (RTV-530). Measurements performed for electron beam energy of 6 and 9 MeV have proven the possibility of using the manufactured samples as bolus in radiotherapy.