大体积脑转移瘤的立体定向放射治疗：优化剂量学参数。

Hypofractionated stereotactic radiotherapy for large brain metastases: Optimizing the dosimetric parameters.

机构信息

Department of radiation oncology, Jean-Perrin center, 63011 Clermont-Ferrand, France.

出版信息

Cancer Radiother. 2021 Feb;25(1):1-7. doi: 10.1016/j.canrad.2020.04.011. Epub 2020 Nov 27.

DOI:10.1016/j.canrad.2020.04.011

PMID:33257109

Abstract

PURPOSE

Stereotactic radiotherapy plays a major role in the treatment of brain metastases (BM). We aimed to compare the dosimetric results of four plans for hypofractionated stereotactic radiotherapy (HFSRT) for large brain metastases.

MATERIAL AND METHODS

Ten patients treated with upfront NovalisTx® non-coplanar multiple dynamic conformal arcs (DCA) HFSRT for≥25mm diameter single BM were included. Three other volumetric modulated arc therapy (VMAT) treatment plans were evaluated: with coplanar arcs (Eclipse®, Varian, VMATc), with coplanar and non-coplanar arcs (VMATnc), and with non-coplanar arcs (Elements Cranial SRS®, Brainlab, VMATnc). The marginal dose prescribed for the PTV was 23.1Gy (isodose 70%) in three fractions. The mean GTV was 27mm.

RESULTS

Better conformity indices were found with all VMAT techniques compared to DCA (1.05 vs 1.28, P<0.05). Better gradient indices were found with VMATnc and DCA (2.43 vs 3.02, P<0.001). High-dose delivery in healthy brain was lower with all VMAT techniques compared to DCA (5.6 to 6.3 cc vs 9.4 cc, P<0.001). Low-dose delivery (V5Gy) was lower with VMATnc or VMATnc than with DCA (81 or 94 cc vs 110 cc, P=0.02).

CONCLUSIONS

NovalisTx® VMAT HFSRT for≥25mm diameter brain metastases provides the best dosimetric compromise in terms of target coverage, sparing of healthy brain tissue and low-dose delivery compared to DCA.

摘要

目的

立体定向放疗在治疗脑转移瘤（BM）中起着重要作用。我们旨在比较 4 种大直径脑转移瘤立体定向适形放疗（HFSRT）分割方案的剂量学结果。

材料与方法

共纳入 10 例接受 NovalisTx®非共面多动态适形弧（DCA）HFSRT 治疗的大直径单脑转移瘤患者。评估了另外 3 种容积调制弧形治疗计划（VMAT）：共面弧（Eclipse®，Varian，VMATc）、共面和非共面弧（VMATnc）和非共面弧（Elements Cranial SRS®，Brainlab，VMATnc）。PTV 的边缘剂量为 23.1Gy（70%等剂量线），分 3 次给予。GTV 平均直径为 27mm。

结果

与 DCA 相比，所有 VMAT 技术的适形指数更好（1.05 比 1.28，P<0.05）。VMATnc 和 DCA 的梯度指数更好（2.43 比 3.02，P<0.001）。与 DCA 相比，所有 VMAT 技术均能降低健康脑组织的高剂量剂量（5.6 至 6.3cc 比 9.4cc，P<0.001）。VMATnc 或 VMATnc 比 DCA 具有更低的低剂量剂量（V5Gy）（81 或 94cc 比 110cc，P=0.02）。