High Energy Beams Dosimetric Intercomparison Study at Institute of Nuclear Medicine and Oncology (INMOL) Lahore, Pakistan

This study involved the measurement of high energy photon beams output from high energy linear accelerator to ensure Quality Assurance (QA) by INMOL. The dosimetric research study enabled us to use combinations of ionization chambers and electrometers to measure the absolute output of various high energy beams i.e., 6MV and 15MV photon beams using the TRS 398 absorbed dose-to-water dosimetry [1-2]. Absorbed dose to water was determined with SSDL dosimetry system using 6MV and 15MV energy beams and measurements parameters at field size of (10x10) cm² , 100cm source to water phantom surface distance (SSD), while 10cm and 110cm source to ionization chamber distances (SCD) for respective radiation energy beams. IAEA water phantom of (30x30x30) cm³ dimension having (10x10) cm² window with 3mm thick Perspex sheet and Perspex inserter of 2mm thick at wall position of thimble of farmer ionization calibrated chambers was used. Depth in water was 5cm and 10cm at respective high energy beam output real time measurement. Ionization chambers were being aligned by using cross laser beams fixation on front walls, cross wires of beam collimator and scale lighted on phantom surface.