Image quality and dose calculation of megavoltage computed tomography in helical tomotherapy / 中华放射肿瘤学杂志

ABSTRACT

Objective To quantitatively investigate the image quality and dose calculation accuracy of megavoltage computed tomography (CT) in helical tomotherapy.Methods The megavoltage CT was used to scan the Cheese phantom,and the geometric accuracy of images,noise,image uniformity,spatial resolution,density-CT value conversion,and dose calculation accuracy were analyzed and compared with conventional kilovoltage CT.Results The geometric accuracy of megavoltage CT images was within 2 mm in three directions.The megavoltage CT was inferior to kilovoltage CT in terms of image noise,uniformity,and spatial resolution.The dose-volume histogram (DVH) in dose reconstruction based on CT images was well consistent with DVH in the kilovohage CT plan.Conclusions The megavoltage CT can obtain images with accurate geometric dimensions and has a low imaging dose and accurate dose calculation,which meets clinical requirements.