Polyvinyl alcohol (PVA) based bolus material for high energy photons and electrons

Abstract

The study focused on the use of fabricated bolus materials based on the polyvinyl alcohol (PVA) to increase the surface dose on high energy photons and electrons. The PVA based bolus materials were fabricated at 2.5, 5, 7.5 and 10% PVA in water at target density of 1.0 g/cm3. The PVA based boluses were scanned by using the computed tomography (CT) scanner along with the solid water phantoms. The percentage depth (PDD) dose of the solid water phantoms and the PVA based bolus materials were measured by using the treatment planning software (TPS) at 6 and 10 MV photons and 6 and 9 MeV electrons. The PDD curved obtained were compared to that of the standard bolus material and the surface dose were measured. The results showed that the PDD curves of solid water phantoms with PVA based bolus materials were consistent with that in standard bolus material within 1.4% percentage of difference for both 6 and 10 MV photons and within 2.9 and 1.4% percentage of differences in 6 and 9 MeV electrons respectively. The increment of surface dose in PVA based bolus materials were in excellent agreement to the standard bolus material and the percentage of PVA did not significantly affect the surface dose. The overall results showed the potential use of the PVA to be used as bolus material for clinical photons and electrons.