Background: This study was designed as a dosimetric feasibility analysis to compare hippocampal-avoidance whole-brain radiotherapy (HA-WBRT) using 3D-CRT, IMRT, and VMAT techniques, with particular attention to clinical applicability in resource-limited settings. While 3D-CRT was used as a reference for conventional WBRT, the primary aim was to determine whether IMRT can serve as an effective and accessible alternative to VMAT for HA-WBRT in centers without advanced technology infrastructure. Methods: Fifteen patients undergoing WBRT for symptom relief were planned using 3D-CRT, IMRT, and VMAT on the Elekta Monaco 6.1.4.0 system. Key organs at risk (OARs) such as the optic nerves, chiasm, eyes, and lenses were considered in the treatment planning. Plans were evaluated based on PTV dose distribution, Conformity Index (CI), Homogeneity Index (HI), and OAR dose constraints (RTOG 0933, NRG-CC001). Gamma pass rate analysis (3%/3 mm) was performed for the IMRT and VMAT plans. Results: IMRT and VMAT significantly reduced the hippocampal dose compared to 3D-CRT, with similar PTV coverage and OAR sparing. The mean Dmaxfor the hippocampus was 15.4 Gy for IMRT and 15.5 Gy for VMAT compared to 31.2 Gy for 3D-CRT. The D100% for the hippocampus was 7.5 Gy for IMRT and 7.6 Gy for VMAT, both well below the RTOG 0933 threshold of 9 Gy, while 3D-CRT delivered 30.3 Gy. Additionally, IMRT and VMAT delivered lower doses to the optic nerves and chiasm. QA results showed gamma pass rates above 96% for all plans. This study focused solely on treatment-planning and dosimetric feasibility without evaluating patient outcomes or clinical follow-up. Conclusions: HA-WBRT with IMRT and VMAT significantly reduced the hippocampal dose while maintaining optimal PTV coverage. VMAT is preferred for its balance of efficacy, protection, and treatment time, while IMRT represents a feasible approach for facilities without VMAT, though it requires stricter dose control and longer treatment times.
背景：本研究旨在进行剂量学可行性分析，比较采用三维适形放疗（3D-CRT）、调强放疗（IMRT）和容积旋转调强放疗（VMAT）技术实施海马保护性全脑放疗（HA-WBRT）的差异，特别关注其在资源有限环境中的临床适用性。研究以3D-CRT作为传统全脑放疗的参照，主要目的是探讨在缺乏先进技术基础设施的医疗中心，IMRT能否作为VMAT的有效且可及的替代方案用于HA-WBRT。 方法：在Elekta Monaco 6.1.4.0系统上，为15例接受姑息性全脑放疗的患者分别制定了3D-CRT、IMRT和VMAT计划。治疗计划设计中考虑了视神经、视交叉、眼球及晶状体等关键危及器官。计划评估基于靶区剂量分布、适形指数、均匀性指数以及危及器官剂量限制（参照RTOG 0933和NRG-CC001标准）。对IMRT和VMAT计划进行了伽马通过率分析（标准为3%/3 mm）。 结果：与3D-CRT相比，IMRT和VMAT在保持相似靶区覆盖和危及器官保护的同时，显著降低了海马区剂量。海马区平均最大剂量：IMRT为15.4 Gy，VMAT为15.5 Gy，而3D-CRT为31.2 Gy。海马区D100%剂量：IMRT为7.5 Gy，VMAT为7.6 Gy，两者均远低于RTOG 0933设定的9 Gy阈值，而3D-CRT则达到30.3 Gy。此外，IMRT和VMAT对视神经和视交叉的照射剂量也更低。质量验证结果显示所有计划的伽马通过率均高于96%。本研究仅聚焦于治疗计划与剂量学可行性，未评估患者预后或临床随访。 结论：采用IMRT和VMAT的HA-WBRT能在维持最佳靶区覆盖的同时显著降低海马区剂量。VMAT因其在疗效、器官保护和治疗时间方面的平衡性更受青睐；而对于不具备VMAT设备的机构，IMRT是一种可行的替代方案，尽管其需要更严格的剂量控制和更长的治疗时间。
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