Clinical Photon Beam Dosimetry

Abstract

Understanding setup of relative and absolute measurements for LINAC (ELEKTA) on Radiation and Isotopes Center Khartoum (RICK) with the new dosimetry equipments, acquired necessary and sufficient skills. The aims of this study are: 1- commission the new linear accelerator and to understand the dosimetry principle underlying, 2- to verify the acquired data with published data such as British Journal of Radiology (BJR), supplementary 25, 3- to determine the absolute dose to the water using IAEA TRS 398 protocol. Computerized water phantom (Blue Phantom) was used to achieve a high accuracy and to gain the time during the measurements of the central axis data of 6 MV for ELEKTA accelerator. The total uncertainty in the determination of the dose to water during calculation of the beam was found to be < 2.5 % and this magnitude within the accepted limits of recommendation of the IAEA protocol ( 2.5%). The comparison of published data of BJR and acquired data represents deviation of 1% in PDD and no any deviation on TMR. The maximum relative difference was achieved in the deviation of 1 mm on the maximum depth and the evaluation the reasons of theses 4 deviation was represented in this study. Investigation on the software of the water phantom may need to be applied.