背景:研究摩纳哥治疗计划系统(摩纳哥TPS)的机架角度增量(Inc)参数设置对直肠癌体积调节电弧治疗(VMAT)计划的剂量学和质量参数的影响。
方法:对2020年至2021年使用摩纳哥TPS系统接受调强放疗的50例直肠癌患者进行了回顾性分析。在相同的优化功能配置和其他参数设置下,VMAT放疗计划中的Inc参数设置为10°,20°,30°,40°。使用剂量-体积直方图(DVH)评估靶区的剂量分布和高危器官(OAR)的辐射剂量。计划目标体积(PTV)和OAR的剂量学差异,以及伽马通过率(GPR)进行了比较。
结果:就目标剂量而言,D98,Dmin,HI,Inc10组的一致性指数(CI)显著低于Inc20、30、40组(P<0.05),Inc10组D2显著高于Inc20组(P=0.009)。我们还发现Inc20和30的CI明显优于Inc40(均P<0.05)。就OAR剂量而言,研究发现Dmean,Dmin,V50%,V45%,Inc10组膀胱V40%低于其他组(均P<0.05),Inc20组的股骨头Dmean低于Inc30组(P<0.05),Inc20对股骨头有较好的保护作用。随着Inc参数设置的增加,MU趋于减少。Inc10组的监测单位(MU)显著高于Inc20、Inc30、Inc40组,Inc20组的MU明显高于Inc40组(均P<0.05)。我们发现,对于3%/3毫米和2%/2毫米标准,每个计划的GPR>90%,符合临床要求。
结论:Inc参数的不同设置对目标剂量有不同程度的影响,OAR剂量,机器MU。重要的是医生根据不同的临床需求选择不同的Inc参数。
BACKGROUND: To investigate the effect of the Increment of gantry angle (Inc) parameter setting of the Monaco Treatment planning system (Monaco TPS) on the dosimetry and quality parameters of the volumetric modulated arc therapy (VMAT) program for rectal cancer.
METHODS: A retrospective analysis was conducted on 50 patients with rectal cancer who underwent intensity modulated radiation therapy using the Monaco TPS system from 2020 to 2021. Under the same optimization function configuration and other parameter settings, the Inc parameters in the VMAT radiotherapy plan were set to 10°, 20°, 30°, and 40°. The dose-volume histogram (DVH) was used to evaluate the dose distribution of the target area and the radiation dose of the organs at risk (OAR). The differences in the dosimetry of the planning target volume (PTV) and OAR, as well as the gamma pass rate (GPR) were compared.
RESULTS: In terms of target dose, D98, Dmin, HI, and conformity index (CI) of Inc10 group was significantly lower than those of Inc20, 30, and 40 groups (P < 0.05), and D2 of Inc10 group was significantly higher than that of Inc20 group (P = 0.009). We also found CI of Inc20 and 30 were significantly better than that of Inc40 (both P < 0.05). In terms of OAR dose, the study found that the Dmean, Dmin, V50%, V45%, and V40% for the bladder of the Inc10 group were lower than those of the other groups (all P < 0.05), the Dmean for femoral head of the Inc20 group was lower than that of the Inc30 group (P < 0.05), and Inc20 showed a better protective effect on the femoral head. The MUs tend to decrease as the Inc parameter setting is increased. The monitor unit (MU) in Inc10 group were significantly higher than those in Inc20, Inc30, and Inc40 groups, and the MU of Inc20 group was significantly higher than that of Inc40 group (both P < 0.05). We found that for the 3%/3 mm and 2%/2 mm standards, the GPRs of each plan were > 90%, which met clinical requirements.
CONCLUSIONS: Different settings of Inc parameters have varying degrees of impact on target dose, OAR dose, and machine MU. It is important for doctors to choose different Inc parameters according to different clinical needs.