Application of a Pencil Ionization Chamber (0.34 cm src='/images/tex/1030.gif' alt='^{3}'> Volume) for src='/images/tex/20576.gif' alt='^{60}'> Co Beams: Experimental and Monte Carlo Results

摘要

Ionization chambers are the most utilized dosimeters for precise measurements of absorbed dose, as required e.g., in radiotherapy. The most common type, for this application, is the Farmer type with a wall made of PMMA and/or graphite. With the aim to test new materials and configurations of ionization chambers, using low-cost and easily-available components, this work presents the study of a device developed at the Calibration Laboratory of IPEN (São Paulo). This dosimeter is a pencil-type cylindrical ionization chamber, with a wall of PVC coated with graphite, for routine use in $^{60}$Co beams. Following international recommendations, several characterization tests were conducted, and all achieved results were found to fulfill those recommendations. The influence of the chamber components on its response was also studied using the PENELOPE Monte Carlo code. According to the obtained results, this prototype presents potential usefulness for routine dosimetric procedures in radiotherapy.