Motion monitoring for cranial frameless stereotactic radiosurgery using video-based three-dimensional optical surface imaging
Motion monitoring for cranial frameless stereotactic radiosurgery using video-based three-dimensional optical surface imaging
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DOI：
10.1118/1.3596526
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发表时间：
2011-07-01
期刊：
影响因子：
3.8
通讯作者：
Amols, Howard
中科院分区：
文献类型：
--
作者：
Li, Guang;Ballangrud, Ase;Amols, Howard
目的：建立一个新的临床程序，在无框架立体定向放射外科（SRS）的患者设置验证治疗床的角度，以及在治疗过程中使用基于视频的光学表面成像（OSI）的头部运动监测方法：一个基于视频的三维（3D）OSI系统与三个天花板安装的摄像头吊舱验证设置在治疗床的角度，以及在治疗过程中监测头部运动。使用了无创头部固定装置，包括一个α头模和一个带真空抽吸的牙套;两者都锁定在治疗床上。锥形束计算机断层扫描（CBCT）被用作图像引导设置的标准。在治疗前、治疗床旋转之间和治疗床角度为零的治疗后，应用正交2D-kV成像进行设置验证。在各种治疗床角度下，通过坐标变换进行CBCT设置后，相对于零治疗床角度下的初始OSI设置验证，进行OSI设置验证。对于运动监测，通过将现场表面图像作为新的参考来解耦设置不确定性，以近实时地（每秒1-2帧）检测运动引起的未对准。对实时监测的初始热不稳定性基线进行了修正。使用一个拟人头部模型和一个1D定位平台来评估OSI在纵向和横向方向上运动检测的准确性。2例低分割（9戈伊x 3和6戈伊x 5）无框架立体定向放射治疗（SRT）患者以及2例单分割（21和18戈伊）无框架SRS患者使用该无框架手术进行治疗。为了进行比较，使用OSI监测11名传统的基于框架的SRS患者，作为临床标准。多个非共面共形光束被用于规划无框架和基于框架的SRS与micromultileaf collimator.Results：OSI在1D运动检测的准确性被发现是0.1毫米的不确定性+/- 0.1毫米使用头部幻影。针对模拟计算机断层扫描（CT）外部轮廓的OSI配准被发现依赖于CT皮肤定义，具有类似于0.4 mm的变化。对于基于帧的SRS患者，头部运动幅度被检测为
Purpose: To establish a new clinical procedure in frameless stereotactic radiosurgery (SRS) for patient setup verification at treatment couch angles as well as for head-motion monitoring during treatment using video-based optical surface imaging (OSI).Methods: A video-based three-dimensional (3D) OSI system with three ceiling-mounted camera pods was employed to verify setup at treatment couch angles as well as to monitor head motion during treatment. A noninvasive head immobilization device was utilized, which includes an alpha head mold and a dental mouthpiece with vacuum suction; both were locked to the treatment couch. Cone beam computed tomography (CBCT) was used as the standard for image-guided setup. Orthogonal 2D-kV imaging was applied for setup verification before treatment, between couch rotations, and after treatment at zero couch angle. At various treatment couch angles, OSI setup verification was performed, relative to initial OSI setup verification at zero couch angle after CBCT setup through a coordinate transformation. For motion monitoring, the setup uncertainty was decoupled by taking an on-site surface image as new reference to detect motion-induced misalignment in near real-time (1-2 frames per second). Initial thermal instability baseline of the real-time monitoring was corrected. An anthropomorphous head phantom and a 1D positioning platform were used to assess the OSI accuracy in motion detection in longitudinal and lateral directions. Two hypofractionated (9 Gy x 3 and 6 Gy x 5) frameless stereotactic radiotherapy (SRT) patients as well as two single-fraction (21 and 18 Gy) frameless SRS patients were treated using this frameless procedure. For comparison, 11 conventional frame-based SRS patients were monitored using the OSI to serve as clinical standards. Multiple noncoplanar conformal beams were used for planning both frameless and frame-based SRS with a micromultileaf collimator.Results: The accuracy of the OSI in 1D motion detection was found to be 0.1 mm with uncertainty of +/- 0.1 mm using the head phantom. The OSI registration against simulation computed tomography (CT) external contour was found to be dependent on the CT skin definition with similar to 0.4 mm variation. For frame-based SRS patients, head-motion magnitude was detected to be