Infuencing factors of hippocampus-sparing whole-brain radiotherapy with helical tomotherapy(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2022年第1期
- Page:
- 14-22
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Infuencing factors of hippocampus-sparing whole-brain radiotherapy with helical tomotherapy
- Author(s):
- WANG Haiyang; PI Yifei; HAN Bin; JIA Fei; LIU Lele; WANG Fangna; KONG Fanyang; PEI Yuntong; HU Jinyan; JI Chuanxian; JI Tengfei; XU Dandan; GUO Yuexin
- Department of Radiation Oncology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
- Keywords:
- Keywords: helical tomotherapy whole-brain radiotherapy hippocampus sparing influencing factors
- PACS:
- R818
- DOI:
- DOI:10.3969/j.issn.1005-202X.2022.01.003
- Abstract:
- Abstract: Objective To study the effects of various parameters on the outcome of hippocampus-sparing whole-brain radiotherapy (HS-WBRT) with helical tomotherapy (HT). Methods Eight patients receiving HS-WBRT were enrolled in the study, and the target areas and organs-at-risk (OAR) were delineated at the Varian Eclipse 13.5 doctors workstation. The left and right hippocampus was delineated based on the fusion of CT images and MR images, and the external expansion of 5 mm was taken as the hippocampus reduction region.The target area was the whole brain minus hippocampal gyrus with an uniform exteranal expansion of 5 mm and OAR included hippocampus, hippocampus reduction region, eyeballs and lens. The delineated structures and images were transmitted to the HT physicist workstation for designing plans with different parameter combinations. The prescribed dose was 25 Gy/10 F. Field widths (FW) was set at 1.0, 2.5, 5.0 cm, respectively, Pitch at 0.215, 0.287, 0.430, and modulation factors (MF) at 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, and the dose calculation grid was 0.195 cm × 0.195 cm. The other planning parameters remained consistent. Finally, the effects of various parameters on the dose distributions of target area and OARs and execution efficiency were statistically analyzed. Results Plans designed with different parameter combinations met clinical requirements. FW and MF were found to have great dosimetric effects on the target area and OAR, while Pitch had no effect on them. From the perspective of plan quality, the dose distribution was the optimal when FW was 1.0 cm, followed by FW of 2.5 cm and FW of 5.0 cm and from the perspective of treatment efficiency, the efficiency was highest when FW was 5.0 cm, followed by FW of 2.5 cm and FW of 1.0 cm. The best choice of MF was about 2.5 for FW of 1.0, and about 4.0 for FW of 2.5 cm and 5.0 cm. Reducing MF would reduce plan quality, while increasing MF was meaningless for improving the dose distribution, and it would only increase treatment delivery time and reduce treatment efficiency. Conclusion During HS-WBRT planning, appropriate planning parameters needed to be selected according to clinical requirements. When focusing on plan quality, FW should be selected at 1.0 cm or 2.5 cm, and at this time, the MF should be about 2.5 or 4.0. When focusing on treatment efficiency, FW at 5.0 cm or 2.5 cm and MF about 4.0 was the optimal choice. When considering both plan quality and execution efficiency, FW at 2.5 cm and MF about 4.0 can balance plan quality and treatment efficiency.
Last Update: 2022-01-17