评估单靶点直线加速器放射外科治疗转移瘤和颅底病变。

Assessment of single isocenter linear accelerator radiosurgery for metastases and base of skull lesions.

机构信息

Department of Radiation Oncology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA.

出版信息

Phys Med. 2021 Jan;81:1-8. doi: 10.1016/j.ejmp.2020.11.011. Epub 2020 Dec 3.

DOI:10.1016/j.ejmp.2020.11.011

PMID:33278764

Abstract

BACKGROUND

Newer technology for stereotactic radiosurgery (SRS) should be assessed for different multi-leaf collimators (MLC).

OBJECTIVE

Assess plan quality of an automated, frameless, linear accelerator based (linac) planning and delivery system (HyperArc) for SRS using both standard MLC (SMLC) and high definition MLC (HDMLC) compared to a cobalt-60 based SRS system (Gamma Knife, GK).

METHODS

We re-planned twenty GK Perfexion-treated SRS patients (27 lesions) for HyperArc using SMLC and HDMLC. We assessed plan quality using the following metrics: gradient index (GI), Paddick and RTOG conformity indices (CI, CI), volume receiving half of prescription isodose (PIV) and maximum dose to 0.03 cc for brainstem, optic chiasm and optic nerves, and V12Gy for brain-GTV.

RESULTS

Linac plans had better conformity with HDMLC being most conformal. GK exhibited better GI. PIV demonstrated no statistically significant difference between HDMLC and GK, and SMLC was nominally worse than GK. Mean PIV was generally 0.85 cc larger for SMLC than HDMLC. For TV > 1.0 cc, the relative differences in CI, GI, and PIV for SMLC vs. HDMLC were less than 21%. For TV less than < 1.0 cc, there were more obvious relative differences for SMLC vs. HDMLC in CI (mean 146%, max 700%), GI (mean 49%, max 162%), and PIV (mean 77%, max 522%). Organ at risk doses were met in all plans.

CONCLUSIONS

New linac-based plans positively compare to GK plans overall. HDMLC should be strongly considered for treatment of lesions < 1.0 cc given the significant improvements in conformity and PIV over SMLC.

摘要

背景

立体定向放射外科（SRS）的新技术应针对不同的多叶准直器（MLC）进行评估。

目的

使用标准多叶准直器（SMLC）和高分辨率多叶准直器（HDMLC）评估基于无框架直线加速器（linac）的自动计划和递送系统（HyperArc）用于 SRS 的计划质量，并与基于钴-60 的 SRS 系统（伽玛刀，GK）进行比较。

方法

我们使用 SMLC 和 HDMLC 为 HyperArc 重新规划了 20 例接受 GK Perfexion 治疗的 SRS 患者（27 个病灶）。我们使用以下指标评估计划质量：梯度指数（GI）、Paddick 和 RTOG 适形指数（CI、CI）、接受处方等剂量线的体积（PIV）和脑干、视交叉和视神经的 0.03 cc 最大剂量，以及脑-GTV 的 V12Gy。

结果

直线加速器计划具有更好的适形性，HDMLC 最适形。GK 表现出更好的 GI。PIV 在 HDMLC 和 GK 之间没有统计学上的显著差异，而 SMLC 则略逊于 GK。SMLC 的平均 PIV 通常比 HDMLC 大 0.85 cc。对于 TV > 1.0 cc，SMLC 与 HDMLC 相比，CI、GI 和 PIV 的相对差异小于 21%。对于 TV < 1.0 cc，SMLC 与 HDMLC 相比，CI（平均 146%，最大 700%）、GI（平均 49%，最大 162%）和 PIV（平均 77%，最大 522%）的相对差异更为明显。所有计划均满足危及器官剂量。