为 Versa HD 进行颅单次共面多靶放射外科治疗的委托。

Commissioning cranial single-isocenter multi-target radiosurgery for the Versa HD.

机构信息

Department of Radiation Oncology, Beaumont Health, Royal Oak, MI, 48073, USA.

出版信息

J Appl Clin Med Phys. 2021 Apr;22(4):108-114. doi: 10.1002/acm2.13223. Epub 2021 Mar 23.

DOI:10.1002/acm2.13223

PMID:33756044

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC8035552/

Abstract

PURPOSE

Brainlab's Elements Multiple Brain Mets SRS (MBMS) is a dedicated treatment planning system for single-isocenter multi-target (SIMT) cranial stereotactic radiosurgery (SRS) treatments. The purpose of this study is to present the commissioning experience of MBMS on an Elekta Versa HD.

METHODS

MBMS was commissioned for 6 X, 6 FFF, and 10 FFF. Beam data collected included: output factors, percent depth doses (PDDs), diagonal profiles, collimator transmission, and penumbra. Beam data were processed by Brainlab and resulting parameters were entered into the planning system to generate the beam model. Beam model accuracy was verified for simple fields. MBMS plans were created on previously treated cranial SRS patient data sets. Plans were evaluated using Paddick inverse conformity (ICI), gradient indices (GI), and cumulative volume of brain receiving 12 Gy. Dosimetric accuracy of the MBMS plans was verified using microDiamond, Gafchromic film, and SRS Mapcheck measurements of absolute dose and dose profiles for individual targets. Finally, an end-to-end (E2E) test was performed with a MR-CT compatible phantom to validate the accuracy of the simulation-to-delivery process.

RESULTS

For square fields, calculated scatter factors were within 1.0% of measured, PDDs were within 0.5% past dmax, and diagonal profiles were within 0.5% for clinically relevant off-axis distances (<10 cm). MBMS produced plans with ICIs < 1.5 and GIs < 5.0 for targets > 10 mm. Average point doses of the MBMS plans, measured by microDiamond, were within 0.31% of calculated (max 2.84%). Average per-field planar pass rates were 98.0% (95.5% minimum) using a 2%/1 mm/10% threshold relative gamma analysis. E2E point dose measurements were within 1.5% of calculated and Gafchromic film pass rates were 99.6% using a 5%/1 mm/10% threshold gamma analysis.

CONCLUSION

The experience presented can be used to aid the commissioning of the Versa HD in the Brainlab MBMS treatment planning system, to produce safe and accurate SIMT cranial SRS treatments.

摘要

目的

Brainlab 的 Elements Multiple Brain Mets SRS（MBMS）是一种专用于单中心多靶（SIMT）颅立体定向放射外科（SRS）治疗的治疗计划系统。本研究的目的是介绍在 Elekta Versa HD 上进行 MBMS 的调试经验。

方法

对 6X、6FFF 和 10FFF 进行了 MBMS 调试。收集的光束数据包括：输出因子、百分深度剂量（PDD）、对角轮廓、准直器传输和半影。光束数据由 Brainlab 处理，生成的参数输入到计划系统中以生成光束模型。通过对简单场进行验证来验证光束模型的准确性。MBMS 计划是根据以前治疗过的颅 SRS 患者数据集创建的。使用 Paddick 逆适形性（ICI）、梯度指数（GI）和 12Gy 累积脑体积来评估计划。使用 microDiamond、Gafchromic 胶片和 SRS Mapcheck 对各个靶区的绝对剂量和剂量分布进行测量，以验证 MBMS 计划的剂量准确性。最后，使用与 MR-CT 兼容的体模进行端到端（E2E）测试，以验证模拟到治疗过程的准确性。

结果

对于方形野，计算的散射因子与实测值相差在 1.0%以内，PDD 超过 dmax 的值在 0.5%以内，临床相关的离轴距离（<10cm）的对角线轮廓在 0.5%以内。MBMS 为大于 10mm 的靶区生成了 ICI<1.5 和 GI<5.0 的计划。使用 microDiamond 测量的 MBMS 计划的平均点剂量与计算值相差在 0.31%以内（最大 2.84%）。使用 2%/1mm/10%相对伽马分析，平均每个野的平面通过率为 98.0%（最小 95.5%）。E2E 点剂量测量值与计算值相差在 1.5%以内，伽马分析使用 5%/1mm/10%阈值时胶片通过率为 99.6%。