THE INFLUENCE OF ION CHAMBER ON LINAC BEAM QUALITY BASED ON THE PERCENTAGE DEPTH DOSE AND DOSE PROFILE PRODUCED

• Main Author: Gurning, Dwita
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/83793
• Institution: Institut Teknologi Bandung

This Monte Carlo simulation-based research using PHITS, in the LINAC commissioning process aims to know the beam quality based on the dose distribution, which is PDD and dose profile. The type of LINAC to be modeled is the Siemen Primus with energies of 6 and 10 MV. There are two conditions to be compared, i.e. LINAC using an ion chamber and without an ion chamber. The ion chamber used is Al2O3. The fieldsize used in this study is 10×10 cm2 and 20×20 cm2 . The PDD and dose profile were obtained using tally deposit, then processed with Ms. Excel. The method used in data processing is quantitative, by calculating the Dmax, flatness, symmetry, and penumbra values generated from the PDD and dose profile curve. Dmax value ranged from 1.5-2.4 cm. The greater the LINAC energy, the greater the Dmax obtained. The symmetry and penumbra values obtained around 0.38-2.04% and 10-27 mm, respectively, showing results in accordance with the standard conditions of AAPM TG 45. However, the flatness value is around 8-15%, does not meet the AAPM TG 45 standard. A good result of flatness, symmetry, and penumbra value is obtained by LINAC with an ion chamber. Therefore, it’s recommended to add an ion chamber to the LINAC head in radiotherapy to ensure better quality of the radiation beam, so the dose delivered is optimal and the therapeutic effect of the therapy is achieved.