不同扫描条件下CBCT图像剂量计算准确性

摘要

分别设计Catphan模体均匀性与非均匀性组织模块扇形束CT计划,利用OBI系统对模体在不同临床条件下进行扫描得到CBCT图像,采用相应CBCT图像HU-ED曲线进行剂量计算并与其扇形束CT计划比较,不同扫描条件下两模块CBCT计划剂量均匀性指数均与其相应扇形束CT计划无差别;均匀组织模块CBCT计划剂量适形指数更接近于扇形束CT计划.不同扫描条件下CBCT图像剂量计算能够满足剂量要求,为其直接用于自适应放疗奠定一定基础.%The treatment plans were designed based on planning CT of Catphan phantom's homogenic and heterogenetical module, respectively. With the OBI system, Catphan phantom was scanned under different scanning conditions. The dose was recalculated by applying treatment plans based on planning CT to the CBCT images with its individual hounsfield unit-electron density calibration curve. The dose distributions were compared with those of the original plan, the results ofHI showed a good agreement.CIs in the homogenic module were superior to those in the heterogenetical one. There is a good dose distribution for CBCT images under different scanning conditions. It is helpful for CBCT images directly used for dose re-calculation in adaptive radiation therapy (ART).