Objectives:Although hippocampal-sparing whole-brain irradiation (HS-WBI) offers potential neurocognitive benefits, it poses challenges in treatment planning. This study aimed to compare the dose distributions of biaxially rotational dynamic radiation therapy (BROAD-RT) with a novel O-ring-type linear accelerator (OXRAY) and conventional non-coplanar volumetric modulated arc therapy (VMAT) planning (Conv-VMAT) in HS-WBI treatment plans.Methods:This study included 10 patients with brain metastases from lung cancer at our institution. The hippocampus was contoured using gadolinium-based contrast-enhanced magnetic resonance imaging, and hippocampal-sparing regions were created using a 5 mm margin around the hippocampus. Two virtual plans (BROAD-RT and Conv-VMAT) with 30 Gy in 10 fractions were created to compare the dose distributions in the planning target volume (PTV), hippocampus, eyes, and lens. All plans were analyzed using a pairedt-test.Results:The mean (standard deviation [SD]) hippocampus-Dmax, -Dmean, -D100%, and -V10 were 11.10 (0.61), 7.95 (0.20), 7.01 (0.19), and 0.42 (0.34) for BROAD-RT and 16.10 (0.57), 9.89 (0.75), 8.24 (0.34), and 39.05 (25.89) for Conv-VMAT, respectively. All hippocampal parameters were significantly better with BROAD-RT than with Conv-VMAT (p< 0.01). The PTV-D98, -D50, -D2, -V35, and -homogeneity index did not exhibit significant differences between BROAD-RT and Conv-VMAT. Although lens-Dmax was significantly better in BROAD-RT than in Conv-VMAT (p< 0.01), no significant differences were observed in the eye-Dmax and chiasm-Dmax between BROAD-RT and Conv-VMAT. The mean (SD) BROAD-RT beam delivery time was 313.60 (34.91) s.Conclusions:BROAD-RT improved hippocampal sparing with acceptable PTV coverage and PTV homogeneity in HS-WBI planning. In addition, BROAD-RT has a clinically acceptable treatment duration.
目的：尽管海马保护性全脑放疗（HS-WBI）具有潜在的神经认知获益优势，但其在治疗计划制定方面存在挑战。本研究旨在比较新型O形环直线加速器（OXRAY）的双轴旋转动态放疗（BROAD-RT）与常规非共面容积旋转调强放疗（Conv-VMAT）在HS-WBI治疗计划中的剂量分布差异。 方法：本研究纳入我院10例肺癌脑转移患者。基于钆对比剂增强磁共振成像勾画海马结构，并以海马外扩5毫米边界创建海马保护区域。分别制定30Gy/10次分割的两种虚拟计划（BROAD-RT与Conv-VMAT），比较计划靶区（PTV）、海马、眼球及晶状体的剂量分布。所有计划均采用配对t检验进行统计分析。 结果：BROAD-RT组海马Dmax、Dmean、D100%及V10的平均值（标准差[SD]）分别为11.10（0.61）、7.95（0.20）、7.01（0.19）和0.42（0.34），而Conv-VMAT组分别为16.10（0.57）、9.89（0.75）、8.24（0.34）和39.05（25.89）。所有海马剂量学参数均显示BROAD-RT显著优于Conv-VMAT（p<0.01）。PTV的D98、D50、D2、V35及均匀性指数在两组间无显著差异。虽然BROAD-RT的晶状体Dmax显著优于Conv-VMAT（p<0.01），但两组在眼球Dmax和视交叉Dmax方面未见显著差异。BROAD-RT的平均（SD）束流照射时间为313.60（34.91）秒。 结论：在HS-WBI计划中，BROAD-RT在保证PTV覆盖度和均匀性可接受的前提下，显著提升了海马保护效果。此外，BROAD-RT具有临床可接受的治疗时长。
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