Analisis Distribusi Dosis Berkas Foton pada Kanker Nasofaring dengan Teknik Intensity Modulated Radiation Therapy (IMRT) menggunakan Pesawat Linear Accelerator di Sub Instalasi Radioterapi RSUP Prof. Dr. I.G.N.G. Ngoerah

Abstract

Analysis for the distribution of photon beam doses in nasopharyngeal cancer has been carried out with the Intensity Modulated Radiation Therapy (IMRT) technique at the Sub-Installation of RSUP Prof. Dr. I.G.N.G. Ngoerah. Calculations were carried out by analyzing the values of the Homogeneity Index (HI) and Conformity Index (CI) as well as radiation dose in Organs a t Risk (OAR). Data from 20 nasopharyngeal cancer patients were used, and a 6 MV energy photon beam with a total dose of 7000 cGy was used, using seven beams of irradiation direction. The data used are radiation doses of 2%, 50%, and 98%, target volume and 95%, and doses at OAR. These data are obtained from the Dose Volume Histogram (DVH) curve in the Treatment Planning System (TPS) process. The results obtained were the average dose distribution on cancer targets in the form of HI and CI values for 20 patients, namely the average HI value of 0.1231±0.0244, while the average CI value was 0.9856±0.022 which, when compared to ICRU report 83 of 2010 HI and CI values were still within the allowable standard limits. The average dose distribution in OAR for 20 patients was the mean spinal cord (4683.9±216.47) cGy, the average right eye (3909.7±605.45) cGy, the average left eye (3683.885±659.89) cGy, the average right optic nerve (4149.01±1099.68) cGy, the average left optic nerve (4174.355±1219.96) cGy, the average right lens (746.29±149.85) cGy, and the average left lens (753.03±144.32) cGy, all average values obtained by OAR are still within the allowable limits. Keywords: nasopharyngeal cancer, 6 MV, IMRT, homogeneity index, conformity index, organ at risk