Effect Of Shielding Thickness On The Transmission Factor Of 4 And 8 Mev Electron Beams: A Comparison Of Cerrobend, Silicone-Pb, And Plasticine

Abstract

Electron radiotherapy using a Linear Accelerator (LINAC) requires effective shielding materials to reduce radiation transmitted to tissues or areas that are not targeted for treatment. This study aimed to analyze the effects of material type and thickness variation on the electron transmission factor and to compare the effectiveness of Cerrobend, Silicone-Pb, and Plasticine at 4 MeV and 8 MeV. The study was conducted at the Radiotherapy Sub-Installation of Prof. I.G.N.G. Ngoerah Hospital, Denpasar, using a LINAC. The materials had thickness variations of 0.5, 1, 1.5, 2, and 2.5 cm, with a 10 × 10 cm field size and an SSD of 100 cm. Dose measurements were performed using the IAEA TRS-398 protocol, and the transmission factor was calculated as the ratio of the dose after passing through the material to the dose without the material. The results showed that increasing material thickness reduced the transmission factor at both energies. Cerrobend produced the lowest transmission factor across all thickness variations. At 4 MeV, Cerrobend met the <5% transmission limit starting at 0.5 cm, whereas Silicone-Pb and Plasticine met the criterion at 1 cm and 1.5 cm, respectively. At 8 MeV, Cerrobend met the criterion starting at 0.5 cm, Silicone-Pb at 1.5 cm, and Plastisine at 2 cm. Increasing electron energy increased the transmission factor. Cerrobend showed the best shielding effectiveness compared with Silicone-Pb and Plasticine.