Comparison of dose distributions among five radiotherapy apparatuses in stereotactic body radiation therapy for pancreatic cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective:To compare the dose distribution among CyberKnife, Tomotherapy, Edge, Triology and γ-knife in stereotactic body radiation therapy (SBRT) for pancreatic cancer.Methods:Clinical data of 10 panreatic cancer patients receiving CyberKinife treatment were retrospectively analyzed. The treatment plans were designed by five apparatuses from five centers according to the uniform requirement. All plans were transferred to MIM system for the extraction of parameters, which mainly included D min, D mean and D max of PTV, conformity index (CI), new conformity index (nCI), homogeneity index (HI), gradient index (GI), coverage, D max and dose-volume of the stomach and bowel. Results:The best CI and nCI were obtained in Triology ( P<0.001), and the worst HI was found in γ-knife ( P<0.001). The best GI was found in CyberKnife, followed by γ-knife and Tomotherapy, and Edge showed the worst GI ( P<0.001). The highest D min of PTV was found in both Edge and Triology, while lower D min of PTV was found in CyberKnife and Tomotherapy ( P<0.001). Additionally, γ-knife provided the highest D mean and D max of PTV ( P<0.001). Regarding the organs at risk, the lowest D max and D 5cm 3 of the bowel ( P<0.001), D max of the stomach ( P=0.003), D max( P=0.001), D 5cm 3 ( P<0.001) and D 10cm 3 ( P=0.005) of the duodenum, D max( P<0.001) and D 0.35cm 3 ( P<0.001) of the spinal cord were found in CyberKnife. The highest D max of the bowel was found in γ-knife. Furthermore, the highest D 5cm 3 of the duodenum was demonstrated in Edge ( P<0.001) and Tomotherapy provided the highest D max( P<0.001) and D 0.35cm 3 of the spinal cord ( P<0.001). Conclusions:All five radiotherapy apparatuses can meet the requirement of SBRT for pancreatic cancer. More rapid dose fall-off could be obtained via CyberKnife and γ-knife. Triology and Edge provide better target conformity. CyberKnife can better protect the gastrointestinal tract.