Department of Radiation Physics, Unit 94, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.
Department of Radiation Physics, Unit 94, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.
Phys Med. 2020 May;73:135-157. doi: 10.1016/j.ejmp.2020.04.013. Epub 2020 Apr 29.
To verify whether Icon automatic correction is robust in preserving plan quality.
MATERIALS/METHODS: An end-to-end phantom was used to verify Icon's correction accuracy qualitatively. For quantitative assessment, two plans, a composite- and a uniform-shot-only, were created for an elliptical- (E) and a sausage-shaped (S) lesion inside a PseudoPatient head phantom with a film insert. The phantom was irradiated in the planned and three other positions under each plan: 14° pitch (B); 14° rotation + 8° pitch (C); 95° rotation + 4-cm shift (D).
Icon accurately corrects the locations of the shots. For the uniform-shot plans: all gamma index passing rates were >97%, and the differences between the planned and the delivery doses (minimum, maximum, and mean) were all ≤0.1 Gy. For the composite-shot plans, however, the dose differences increased as the phantom was shifted through positions B-D, with a gamma index passing rate of 61% for lesion-E in position D, and 92%, 79%, and 45% for lesion-S in positions B, C, and D, respectively.
Plans using only uniform shots are more robust to deviations in treatment position. The tolerance for such deviations may be lower for plans using composite shots.
验证 Icon 自动校正是否能稳定保持计划质量。
材料/方法：使用端对端体模，对 Icon 的校正准确性进行定性验证。为了进行定量评估，针对椭圆（E）和香肠形（S）两种病变，在 PseudoPatient 头部体模中创建了一个复合射野和一个纯射野计划，并在体模内插入胶片。在计划和每个计划的另外三个位置下对体模进行照射：14°螺距（B）；14°旋转+8°螺距（C）；95°旋转+4cm 偏移（D）。
Icon 能准确校正射野位置。对于纯射野计划：所有伽马指数通过率均>97%，计划剂量与实际剂量（最小、最大和平均值）的差异均≤0.1Gy。然而，对于复合射野计划，随着体模在 B-D 位置移动，剂量差异增加，病变 E 在位置 D 的伽马指数通过率为 61%，病变 S 在位置 B、C 和 D 的伽马指数通过率分别为 92%、79%和 45%。
仅使用纯射野的计划对治疗位置的偏差更具鲁棒性。对于使用复合射野的计划，这种偏差的容忍度可能更低。
