使用 3D 拟人化凝胶体模对单个等中心点进行 SRS 治疗多发性转移瘤时，表面引导成像与立体 X 射线的端到端对比。

End to end comparison of surface-guided imaging versus stereoscopic X-rays for the SRS treatment of multiple metastases with a single isocenter using 3D anthropomorphic gel phantoms.

机构信息

Department of Radiation Oncology, The University of Texas Health at San Antonio, San Antonio, Texas, USA.

Department of Biomedical Sciences, Radiology and Radiotherapy Sector, University of West Attica, Athens, Greece.

出版信息

J Appl Clin Med Phys. 2022 May;23(5):e13576. doi: 10.1002/acm2.13576. Epub 2022 Mar 24.

DOI:10.1002/acm2.13576

PMID:35322526

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC9121024/

Abstract

INTRODUCTION

Two end-to-end tests evaluate the accuracy of a surface-guided radiation therapy (SGRT) system (CRAD Catalyst HD) for position verification in comparison to a stereoscopic x-ray imaging system (Brainlab Exactrac ) for single-isocenter, multiple metastases stereotactic radiosurgery (SRS) using 3D polymer gel inserts.

MATERIALS AND METHODS

A 3D-printed phantom (Prime phantom, RTsafe PC, Athens, Greece) with two separate cylindrical polymer gel inserts were immobilized in open-face masks and treated with a single isocentric, multitarget SRS plan. Planning was done in Brainlab (Elements) to treat five metastatic lesions in one fraction, and initial setup was done using cone beam computed tomography. Positional verification was done using orthogonal X-ray imaging (Brainlab Exactrac) and/or a surface imaging system (CRAD Catalyst HD, Uppsala, Sweden), and shift discrepancies were recorded for each couch angle. Forty-two hours after irradiation, the gel phantom was scanned in a 1.5 Tesla MRI, and images were fused with the patient computed tomography data/structure set for further analysis of spatial dose distribution.

RESULTS

Discrepancies between the CRAD Catalyst HD system and Brainlab Exactrac were <1 mm in the translational direction and <0.5° in the angular direction at noncoplanar couch angles. Dose parameters (D D ) and 3D gamma index passing rates were evaluated for both setup modalities for each planned target volume (PTV) at a variety of thresholds: 3%/2 mm (Exactrac≥93.1% and CRAD ≥87.2%), 5%/2 mm (Exactrac≥95.6% and CRAD ≥94.6%), and 5%/1 mm (Exactrac≥81.8% and CRAD ≥83.7%).

CONCLUSION

Dose metrics for a setup with surface imaging was found to be consistent with setup using x-ray imaging, demonstrating high accuracy and reproducibility for treatment delivery. Results indicate the feasibility of using surface imaging for position verification at noncoplanar couch angles for single-isocenter, multiple-target SRS using end-to-end quality assurance (QA) testing with 3D polymer gel dosimetry.

摘要

简介

本研究通过使用 3D 聚合物凝胶插入物，比较末端对末端测试（CRAD Catalyst HD）与立体 X 射线成像系统（Brainlab Exactrac）在单等中心、多转移立体定向放射外科（SRS）中对位置验证的准确性，评估一种表面引导的放射治疗（SGRT）系统（CRAD Catalyst HD）的准确性。该研究使用了一个带有两个独立圆柱形聚合物凝胶插入物的 3D 打印体模（Prime 体模，RTsafe PC，希腊雅典），该体模被固定在开放式面罩中，并接受单次等中心多靶 SRS 计划的治疗。计划在 Brainlab（Elements）中进行，以在一个分数中治疗五个转移性病变，初始设置使用锥形束计算机断层扫描。使用正交 X 射线成像（Brainlab Exactrac）和/或表面成像系统（CRAD Catalyst HD，瑞典乌普萨拉）进行位置验证，并记录每个治疗床角度的移位差异。照射后 42 小时，在 1.5T MRI 中扫描凝胶体模，并将图像与患者的计算机断层扫描数据/结构集融合，以进一步分析空间剂量分布。

结果

在非共面治疗床角度下，CRAD Catalyst HD 系统与 Brainlab Exactrac 的差异在平移方向上<1mm，在角度方向上<0.5°。对于每个计划靶区（PTV），在不同的阈值下（3%/2mm（Exactrac≥93.1%，CRAD≥87.2%）、5%/2mm（Exactrac≥95.6%，CRAD≥94.6%）和 5%/1mm（Exactrac≥81.8%，CRAD≥83.7%），评估了两种设置模式的剂量参数（D D）和 3D 伽马指数通过率。