IMPROVEMENT OF IMAGE QUALITY IN MEGAVOLTAGE CT SCANNING

FIRST REPORT: EXPERIMENTAL EVALUATION WITH THE SECOND GENERATION SCANNING

Abstract

The authors developed a third generation mode megavoltage CT scanner for accelerator treatment beams with a detector unit installed opposing to the gantry head. They intended to improve the accuracy of patient positioning and collimator opening in the rotational conformal radiotherapy. However, insufficient spatial resolution caused by heavy metal collimator to eliminate scanning doses limits its availability. A second generation mode megavoltage scanner using a turn-table has been developed, and spatial resolution of 0.5mm and contrast resolution of 2% as well as visually better image quality were advantageous as compared to those reported with the third generation mode megavoltage scanner.