WE-G-213CD-03：一种用于Vero SBRT动态肿瘤追踪的双互补验证方法。

WE-G-213CD-03: A Dual Complementary Verification Method for Dynamic Tumor Tracking on Vero SBRT.

作者信息

Poels K, Depuydt T, Verellen D, De Ridder M

出版信息

Med Phys. 2012 Jun;39(6Part28):3971. doi: 10.1118/1.4736204.

DOI:10.1118/1.4736204

PMID:28519620

Abstract

PURPOSE

to use complementary cine EPID and gimbals log file analysis for in-vivo tracking accuracy monitoring.

METHODS

A clinical prototype of dynamic tracking (DT) was installed on the Vero SBRT system. This prototype version allowed tumor tracking by gimballed linac rotations using an internal-external correspondence model. The DT prototype software allowed the detailed logging of all applied gimbals rotations during tracking. The integration of an EPID on the vero system allowed the acquisition of cine EPID images during DT. We quantified the tracking error on cine EPID (E-EPID) by subtracting the target center (fiducial marker detection) and the field centroid. Dynamic gimbals log file information was combined with orthogonal x-ray verification images to calculate the in-vivo tracking error (E-kVLog). The correlation between E-kVLog and E-EPID was calculated for validation of the gimbals log file. Further, we investigated the sensitivity of the log file tracking error by introducing predefined systematic tracking errors. As an application we calculate gimbals log file tracking error for dynamic hidden target tests to investigate gravity effects and decoupled gimbals rotation from gantry rotation. Finally, calculating complementary cine EPID and log file tracking errors evaluated the clinical accuracy of dynamic tracking.

RESULTS

A strong correlation was found between log file and cine EPID tracking error distribution during concurrent measurements (R=0.98). We found sensitivity in the gimbals log files to detect a systematic tracking error up to 0.5 mm. Dynamic hidden target tests showed no gravity influence on tracking performance and high degree of decoupled gimbals and gantry rotation during dynamic arc dynamic tracking. A submillimetric agreement between clinical complementary tracking error measurements was found.

CONCLUSIONS

Redundancy of the internal gimbals log file with x-ray verification images with complementary independent cine EPID images was implemented to monitor the accuracy of gimballed tumor tracking on Vero SBRT. Research was financially supported by the Flemish government (FWO), Hercules Foundation and BrainLAB AG.

摘要

目的

运用互补的电影式电子射野影像装置（cine EPID）和万向节日志文件分析来监测体内跟踪精度。

方法

在Vero立体定向体部放疗（SBRT）系统上安装了动态跟踪（DT）的临床原型。该原型版本通过使用内部 - 外部对应模型，允许利用万向节直线加速器旋转进行肿瘤跟踪。DT原型软件允许在跟踪过程中详细记录所有应用的万向节旋转。在vero系统上集成EPID使得在DT过程中能够采集电影式EPID图像。我们通过减去目标中心（基准标记检测）和射野质心来量化电影式EPID上的跟踪误差（E - EPID）。将动态万向节日志文件信息与正交X射线验证图像相结合，以计算体内跟踪误差（E - kVLog）。计算E - kVLog和E - EPID之间的相关性以验证万向节日志文件。此外，我们通过引入预定义的系统跟踪误差来研究日志文件跟踪误差的敏感性。作为一个应用，我们计算动态隐藏目标测试的万向节日志文件跟踪误差，以研究重力效应以及万向节旋转与机架旋转的解耦。最后，计算互补的电影式EPID和日志文件跟踪误差来评估动态跟踪的临床准确性。

结果

在同步测量期间，日志文件和电影式EPID跟踪误差分布之间发现了很强的相关性（R = 0.98）。我们发现万向节日志文件能够检测到高达0.5毫米的系统跟踪误差。动态隐藏目标测试表明，在动态弧形动态跟踪期间，重力对跟踪性能没有影响，并且万向节和机架旋转高度解耦。临床互补跟踪误差测量之间发现了亚毫米级的一致性。