Abstract：
This study aimed to clarify the differences in radiotherapy dose characteristics and delivery efficiency between the supine and prone positions in patients with prostate cancer using the CyberKnife. The planning computed tomography (CT) and delineations of the prone position were obtained by rotating the supine CT images with delineations of 180° using image processing software. The optimization parameters for planning target volume (PTV) and organs at risk (OARs) were based on the prone position. The optimization parameters determined for the prone position were applied to the supine position for optimization and dose calculation. The dosimetric characteristics of the PTV and OARs, and delivery efficiency were compared between the two different patient positions. The plans in the prone position resulted in better PTV conformity index (nCI), rectum V90%, V80%, V75%, V50% and bladder V50%. A significant difference was observed in treatment time and depth along the central axis (dCAX) between the two plans. The mean treatment time per fraction and dCAX for the supine and prone positions were 20.9 ± 1.7 min versus 19.8 ± 1.3 min (P = 0.019) and 151.1 ± 33.6 mm versus 233.2 ± 8.8 mm (P < 0.001), respectively. In this study the prone position was found to improve dosimetric characteristics and delivery efficiency compared with the supine position during prostate cancer treatment with the CyberKnife.
摘要：
本研究旨在阐明使用射波刀的前列腺癌患者仰卧位和俯卧位之间放疗剂量特征和递送效率的差异。通过使用图像处理软件旋转仰卧位CT图像以180°的轮廓来获得计划计算机断层扫描（CT）和俯卧位的轮廓。计划目标体积（PTV）和危险器官（OAR）的优化参数基于俯卧位。将针对俯卧位确定的优化参数应用于仰卧位以进行优化和剂量计算。PTV和OAR的剂量学特性，比较了两种不同患者体位之间的分娩效率。俯卧位的计划导致更好的PTV符合性指数(nCI)，直肠V90%,V80%,V75%,V50%和膀胱V50%。在两个计划之间，沿中心轴（dCAX）的治疗时间和深度存在显着差异。仰卧位和俯卧位的平均每分治疗时间和dCAX分别为20.9±1.7min和19.8±1.3min（P=0.019）和151.1±33.6mm和233.2±8.8mm（P<0.001），分别。在这项研究中，与使用射波刀治疗前列腺癌期间的仰卧位相比，俯卧位被发现可以改善剂量学特征和递送效率。
