4π 计划在保护脑皮质的放射治疗中的优化。
4π plan optimization for cortical-sparing brain radiotherapy.
机构信息
Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California, United States.
Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California, United States.
出版信息
Radiother Oncol. 2018 Apr;127(1):128-135. doi: 10.1016/j.radonc.2018.02.011. Epub 2018 Mar 5.
BACKGROUND AND PURPOSE
Incidental irradiation of normal brain tissue during radiotherapy is linked to cognitive decline, and may be mediated by damage to healthy cortex. Non-coplanar techniques may be used for cortical sparing. We compared normal brain sparing and probability of cortical atrophy using 4π radiation therapy planning vs. standard fixed gantry intensity-modulated radiotherapy (IMRT).
MATERIAL AND METHODS
Plans from previously irradiated brain tumor patients ("original IMRT", n = 13) were re-planned to spare cortex using both 4π optimization ("4π") and IMRT optimization ("optimized IMRT"). Homogeneity index (HI), gradient measure, doses to cortex and white matter (excluding tumor), brainstem, optics, and hippocampus were compared with matching PTV coverage. Probability of three grades of post-treatment cortical atrophy was modeled based on previously established dose response curves.
RESULTS
With matching PTV coverage, 4π significantly improved HI by 27% (p = 0.005) and gradient measure by 8% (p = 0.001) compared with optimized IMRT. 4π optimization reduced mean and equivalent uniform doses (EUD) to all standard OARs, with 14-15% reduction in hippocampal EUD (p ≤ 0.003) compared with the other two plans. 4π significantly reduced dose to fractional cortical volumes (V, V and V) compared with the original IMRT plans, and reduced cortical V by 7% (p = 0.008) compared with optimized IMRT. White matter EUD, mean dose, and fractional volumes V, V and V were also significantly lower with 4π (p ≤ 0.001). With 4π, probability of grade 1, 2 and 3 cortical atrophy decreased by 12%, 21% and 26% compared with original IMRT and by 8%, 14% and 3% compared with optimized IMRT, respectively (p ≤ 0.001).
CONCLUSIONS
4π radiotherapy significantly improved cortical sparing and reduced doses to standard brain OARs, white matter, and the hippocampus. This was achieved with superior PTV dose homogeneity. Such sparing could reduce the probability of cortical atrophy that may lead to cognitive decline.
背景与目的
放射治疗过程中对正常脑组织的偶然照射与认知能力下降有关，这种下降可能是由健康皮层损伤引起的。非共面技术可用于皮层保护。我们比较了 4π 放射治疗计划与标准固定龙门强度调制放射治疗（IMRT）在保护正常脑组织和皮层萎缩概率方面的差异。
材料与方法
对以前接受过脑肿瘤放射治疗的患者（“原始 IMRT”，n=13）的计划进行重新规划，使用 4π 优化（“4π”）和 IMRT 优化（“优化 IMRT”）来保护皮层。比较了同型指数（HI）、梯度测量、皮层和白质（不包括肿瘤）、脑干、光学和海马体的剂量，以及与匹配的 PTV 覆盖范围的一致性。基于以前建立的剂量反应曲线，对治疗后皮层萎缩 3 个等级的概率进行了建模。
结果
在匹配 PTV 覆盖的情况下，与优化 IMRT 相比，4π 显著提高了 HI（提高了 27%，p=0.005）和梯度测量（提高了 8%，p=0.001）。与其他两种方案相比，4π 优化降低了所有标准 OAR 的平均剂量和等效均匀剂量（EUD），其中海马体 EUD 降低了 14-15%（p≤0.003）。与原始 IMRT 计划相比，4π 显著降低了部分皮层体积（V、V 和 V）的剂量，与优化 IMRT 相比，皮层 V 降低了 7%（p=0.008）。白质 EUD、平均剂量和部分体积 V、V 和 V 也随着 4π 的应用而显著降低（p≤0.001）。与原始 IMRT 相比，使用 4π 后，1 级、2 级和 3 级皮层萎缩的概率分别降低了 12%、21%和 26%，与优化 IMRT 相比，概率分别降低了 8%、14%和 3%（p≤0.001）。
结论
4π 放射治疗显著改善了皮层保护，并降低了标准脑 OARs、白质和海马体的剂量。这是通过更好的 PTV 剂量均匀性实现的。这种保护可能会降低导致认知能力下降的皮层萎缩的概率。
Zotero 插件