A Comparative Study of Dosimetric Characterization of Bolus Based on Natural Rubber (Hevea Brasiliensis) and Clinical Bolus for Therapy with Megavolt Electron Radiation

Abstract

The aim of this study is to evaluate the dosimetry properties of the synthesized bolus material from natural rubber compared to clinical boluses (Play-Doh and Paraffin Wax), involving the values of relative electron density (RED), transmission factor value (TF), mass attenuation coefficient (MAC), percentage surface dose (PSD), and curve of percentage depth dose. In this study, all boluses have dimensions of 11×11×0.5 cm3. Bolus density was measured and analyzed using a CT SCAN and treatment planning system. On the other side, the dosimetry test was performed using Linear Accelerator (LINAC) and detector plan parallel chamber (PPC-40) with an electron beam energy source (6, 9, 12 MeV). Relative electron density for natural rubber bolus, Play-Doh, and paraffin wax were obtained around 0.80, 0.91, and 0.79, respectively. These results indicate that the natural rubber bolus has close to the value of soft tissues such as the lung. Based on the calculation, the transmission factor and the mass attenuation coefficient of natural rubber have the best absorber properties achieved at 12 MeV energy with the results of 99.83% and 0.0045 cm2/g; this also occurred in the clinical boluses. The surface dose experienced an increase in each addition of energy as much as 8.73, 5.35, and 4.79% for energy sources 6, 9, and 12 MeV, respectively. Therefore it can be concluded that the bolus synthesized by natural rubber can be used as an alternative bolus alongside the clinical bolus in this study (paraffin wax and Play-Doh) in the treatment of superficial cancer using megavolt electron energy.