Study on Star Shot Analysis for Physics Quality Assurance in Radiotherapy

摘要

Star shot analysis is one common and important module in physics quality assurance (QA) which is regularly performed on the radiotherapy machine. A star shot analysis method by image processing is proposed. First, through ROI selection and image binarization, the irrelevant image parts are excluded and the star-shots are highlighted. Then the center and beam branches of the shots are determined by iteration, coordinate transformation, threshold value's analysis and image segmentation. Finally, beam center lines and a minimum circle encompassing beam intersections are calculated by mathematic operations. The proposed method is performed on three star shot films and all beam center lines, beam intersections and minimum circles are obtained instantly and showed clearly. The results present good consistency with the commercial verification software and indicate that the proposed method provides the physicist a considerable comparison in physics QA.