No abstract

Bolus is a material equivalent to tissue and used in radiotherapy process to increase a dose surface using electron beam. The bolus synthesis from a material equivalent to tissue is not easy, one of the alternative materials used is silicone rubber (SR). In this research bolus was synthesized with dimension of length x width x thickness is (17 x 17 x 1) cm3. Bolus has been characterized by CT-Scan to find relative electron density (RED) and linear accelerator (LINAC) to investigate percentage of surface dose (PSD) with two energy (8 MeV and 10 MeV). The RED value for bolus is 1.176, these results show the RED value for bolus between soft tissue and solid tissue. The PSD value at 8 MeV and 10 MeV are 102.32% and 101.32%, respectively. These results indicate that the silicone rubber material can be used as an alternative bolus material because it corresponds to the bolus function in radiotherapy.

Bolus is a material that equal with the tissue and functions to increase the dose radiation in surface area in external radiotherapy, which uses electron beam. In this research, bolus was made using silicone rubber (SR) material, which was mixed with silicacomposites material. The bolus with a dimension of 12 x 12 x 0,5 cm3 was successfully made with a various amount of silica composite (2%, 4%, 6%). Bolus was then characterized using linear accelerator (LINAC) with an electron beam for percentage of surface dose (PSD) and using CT-Scan to measurement relative electron density (RED). The energy of electron beam used in this research was5 and 7 MeV. The result shows that RED value increased with increasing the amount of silica composite with higher RED value amounted to 1.186. PSD value increased with increasing the amount of silica composite, higher PSD value of energy in 5 and 7 MeV amounted 106.82% and 106.82% and 100.34%, respectively. The result certified that the silica composite material can increase the percentage of surface dose on electron beam radiotherapy.

Imaging using CT Scan utilizes the nature of the material that can absorb X-rays so the intensity of X-rays that penetrate the material will be attenuated. The attenuation coefficient of the material will provide information on the physical properties of it, in the image produced by CT Scan, the attenuation coefficients of the material is related to the number of Hounsfield Unit (HU). Alginate impression material is an irreversible hydrocolloid molding material that will form a gel when reacted with water without heating treatment process. The nature of alginate gel is elastic and has a fast setting time, often used in the manufacture of dentures. Alginate scanning using CT scan can provide information on alginate gel equivalents with human body tissue by comparing the HU values obtained. Alginate impression material that has been set up by using water is formed with a size of 11 x 11 cm with a thickness varying 5 mm, 7 mm and 9 mm and then scanned using CT Scan obtained an average HU of -51, which is equivalent to soft tissue such as lipid or breast.