Application of geometric uncertainty-based robust optimization in stereotactic body radiotherapy for liver cancer(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2022年第2期
- Page:
- 162-168
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Application of geometric uncertainty-based robust optimization in stereotactic body radiotherapy for liver cancer
- Author(s):
- LIU Denghong; WANG Xuetao; ZHONG Renming
- Department of Radiotherapy (State Key Laboratory of Biotherapy), Cancer Center, West China School of Medicine (West China Hospital), Sichuan University, Chengdu 610041, China
- Keywords:
- Keywords: liver cancer stereotactic body radiotherapy robust optimization geometric uncertainty
- PACS:
- R318；R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2022.02.006
- Abstract:
- Abstract: Objective To analyze the effects of robust optimization plan based on geometric uncertainty on the dose distribution of stereotactic body radiotherapy (SBRT) for liver cancer. Methods Twelve patients treated by SBRT for liver cancer were enrolled in the study. For each case, 3 different kinds of plans were designed by different optimization methods, including ① conventional optimization (PTV-Based Plan) based on PTV (ITV-PTV 5 mm), ② robust optimization (Robust Planactual) based on non-uniform geometric uncertainty for ITV (the uncertainties calculated by our center were 7 mm in superior-inferior direction, 4 mm in medial-lateral and anterior-posterior directions), ③ robust optimization (Robust Plan5 mm) based on uniform geometric uncertainty of 5 mm for ITV. All plans were based on the target that 95% ITV met the prescribed dose, and the perturbation dose was calculated with uniform uncertainties of 4, 5, 7 mm from the isocenter to evaluate the robustness. Results The homogeneity index of plans ①②③ was 0.083±0.027, 0.099±0.035 and 0.096±0.026, respectively, without statistical significance and the conformity index of plans ②③ was 1.02±0.05, 1.00±0.04, significantly different from that of plan ① which was 0.98±0.02. Compared with those in plans ①②, the average dose to normal liver tissues in plan ③ was decreased by 4.1% and 2.5% (P=0.034, P=0.021), and V2500 was decreased by 5.4% and 3.0% (P=0.004, P=0.004), respectively. The average dose to normal liver tissue and V2500 in plan ② were not statistically different from those in plan ① (P=0.308 and P=0.182), but decreased by 1.6% and 2.5%. For robustness, the differences in dose-volume histogram bandwidth (DVHBW) of 5 mm-D99%, 5 mm-D98%, 5 mm-D95% in plans ②③ were smaller than those in plan ①. With the increase of setup uncertainty, the difference in DVHBW became greater. Conclusion In liver SBRT, robust optimization can optimize target dose distribution. Even if the setup uncertainty increases, it can still ensure the dose coverage of ITV, without increasing the irradiation dose to normal tissues.
Last Update: 2022-03-07