Abstract：Objective To study the dosimetry effect of volumetric modulated arc therapy (VMAT) with different collimator
angles for eEndometrial carcinoma. Methods A double full-arc VMAT plan was designed for 2 patients at first. The plan with
collimator angle of Arc1 was set to 0-45° with 5° intervals. Arc2 was divided into A (Arc2=360°-Arc1) and B (Arc2=90°-Arc1) two
groups. The line graphs of two groups with the HI, CI, Dmax, V30 and Dmean of the rectum and bladder, and V20 and Dmean of the femoral
heads were drawn as Arc1 to analyze the trend. Then 9 patients were selected for the same plan design, and the dose parameters of
11 patients were tested by t test to obtain the grouping with better results, and the dose parameters under different Arc1 angles in the
better group were statistically analyzed. Results The first 2 patients selected adopted group B plan with small Arc1 Angle, which
could obtain better conformation and uniformity of target area, and effectively reduce the dose of rectum and bladder. A comparison
between groups A and B showed that when Arc1 was 0 and 5°, the CI of group B was better than group A (P<0.05). When
Arc1≤25°, the HI of group B was better than group A (P<0.05). The rectum dose of group B was lower than that of group A (P<0.05)
except for Arc1=45°. The bladder dose of group B was lower than that of group A (P<0.05) when Arc1≤30°. The result analysis
indicated that the plan of group B was better than group A. Then the analysis of the plan of Group B with different Arc1 angles found
that Compared with Arc1=5°, when Arc1≥35°, the CI value became lower (P<0.05). When Arc1≥30°, the HI value became lager
(P<0.05). When Arc1≥25°, Dmax value became larger (P<0.05). When Arc1 was 5° and 10°, the bladder dose was lower than other
angles (P<0.05), and when Arc1=5°, the rectum dose was lower than Arc1=10°(P<0.05). Conclusion In the design of the doublearc
plan for endometrial carcinoma, the collimator angle can be prioritized to use the combination of Arc1 and 90°-Arc1. Compared
with other collimator angles, when the collimator angles Arc1=5° and Arc2=85°, it can effectively improve the conformity and
homogeneity of the target area, and reduce the rectum and bladder dose.
钟思瑶，徐程，孙斌，高玉艳. 准直器角度对子宫内膜癌VMAT计划剂量的影响[J]. 中国医疗设备, 2022, 37(2): 51-56.
ZHONG Siyao, XU Cheng, SUN Bin, GAO Yuyan. Dosimetry Effect of VMAT with Different Collimator Angles for Endometrial Carcinoma. China Medical Devices, 2022, 37(2): 51-56.
