Optimization of the imaging protocol of an X-ray CT scanner for evaluation of normoxic polymer gel dosimeters

Abstract

X-ray computer tomography (CT) has previously been reported as an evaluation tool for polymer gel (PAG) dosimeters. In this study, the imaging protocol of a Siemens Emotion X-ray CT scanner was optimized to evaluate PAGAT normoxic gel dosimeters. The scan parameters were optimized as 130 kV and 150 mA with a slice thickness of 3 mm for smaller fields and 5 mm for larger fields of irradiation. The number of images to be averaged to reduce noise to an acceptable level was concluded to be 25. It was also concluded that the total monomer concentration required is 7% with 10 mM THP to obtain a maximum change in CT number at dose levels up to 15 Gy for evaluation with X-ray CT. Optimal scan parameters may vary with X-ray CT scanner. Hence the imaging protocol of each scanner to be used for evaluating polymer gels requires individual optimization for the purposes of gel dosimetry evaluation.