RADIOBIOLOGICAL STUDY OF THE EFFECT OF THE NUMBER OF RADIATION BEAM DIRECTIONS IN INTENSITY MODULATED RADIATION THERAPY FOR NASOPHARYNGEAL CANCER

• Main Author: Luthfia Hazmar, Ayunda
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/77113
• Institution: Institut Teknologi Bandung

Indonesia ranks third in the world for nasopharyngeal cancer (NPC) cases, with a total of 19,934 documented cases, and second in the number of fatalities, with 13,399. One of the treatments for NPC is radiotherapy utilizing the Intensity Modulated Radiation Therapy (IMRT) approach. The goal of this study is to conduct radiobiological investigations to determine the impact of the number of radiation beams in IMRT on nasopharyngeal cancer. This study's radiobiological investigation employs the Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) methodologies, which are derived from Equivalent Uniform Dose (EUD) computations. A qualitative descriptive study approach was developed to attain this purpose, with secondary data acquired from Hasan Sadikin Hospital (RSHS) in Bandung. The data is the outcome of a Treatment Planning System (TPS) using IMRT procedures on eight patients with varying numbers of radiation beams: 5, 7, and 9 beams, all treated with a 6 MV LINAC system. Information is taken from this data in the form of Dose-Volume Histograms (DVH) and statistical DVH data. This data is used to calculate the dosage and volume for the target as well as the Organs at Risk (OAR). The DVH curve is used to calculate dosage percentiles such as TCD50 and volume V95. Statistical DVH data includes information such as maximum dose, minimum dosage, prescription dose, target volume, and the volume of organs at risk that have been exposed to radiation. In this evaluation, the parameters analyzed from the treatment planning results include DVH and its statistical data, TCP, and NTCP. To make these determinations, radiobiological parameters such as ?, ?, ????50 , and penalty parameter (a) obtained from existing literature are required. To calculate TCP and NTCP, clinical effectiveness (EQD2) is initially computed, followed by EUD, using radiobiological parameters and dose and volume information obtained from DVH data. Following the computation results, which are displayed as TCP and NTCP percentages, an analysis is performed by comparing these values to predetermined criteria derived from the available literature. TCP has a minimum requirement of > 80%, while NTCP has a maximum criterion of 5% for organs such as the brainstem, eyes, lens, and spinal cord. According to the findings of the study, all eight nasopharyngeal carcinoma patients assessed met the predefined criteria. Overall, treatment planning using 5 radiation beams produced the best accuracy rate of 95.93% when compared to 7 and 9 radiation beams. As a result, the five-way planning is the optimal planning for nasopharyngeal cancer with the IMRT approach.