Department of Radiation and Cellular Oncology, The University of Chicago, Chicago, Illinois 60637-1470.
Med Phys. 2013 Nov;40(11):111712. doi: 10.1118/1.4823757.
The spatial and temporal tracking performance of a commercially available 3D optical surface imaging system is evaluated for its potential use in frameless stereotactic radiosurgery head tracking applications.
Both 3D surface and infrared (IR) marker tracking were performed simultaneously on a head phantom mounted on an xyz motion stage and on four human subjects. To allow spatial and temporal comparison on human subjects, three points were simultaneously monitored, including the upper facial region (3D surface), a dental plate (IR markers), and upper forehead (IR markers).
For both static and dynamic phantom studies, the 3D surface tracker was found to have a root mean squared error (RMSE) of approximately 0.30 mm for region-of-interest (ROI) surface sizes greater than 1000 vertex points. Although, the processing period (1/fps) of the 3D surface system was found to linearly increase as a function of the number of ROI vertex points, the tracking accuracy was found to be independent of ROI size provided that the ROI was sufficiently large and contained features for registration. For human subjects, the RMSE between 3D surface tracking and IR marker tracking modalities was 0.22 mm left-right (x-axis), 0.44 mm superior-inferior (y-axis), 0.27 mm anterior-posterior (z-axis), 0.29° pitch (around x-axis), 0.18° roll (around y-axis), and 0.15° yaw (around z-axis).
3D surface imaging has the potential to provide submillimeter level head motion tracking. This is provided that a highly accurate camera-to-LINAC frame of reference calibration can be performed and that the reference ROI is of sufficient size and contains suitable surface features for registration.
评估一种商用的 3D 光学表面成像系统的空间和时间跟踪性能，以评估其在无框架立体定向放射外科头部跟踪应用中的潜力。
在 xyz 运动台上安装头部模型，并对 4 名人类受试者同时进行 3D 表面和红外 (IR) 标记跟踪。为了允许在人类受试者上进行空间和时间比较，同时监测三个点，包括上面部区域（3D 表面）、牙板（IR 标记）和额头上部（IR 标记）。
对于静态和动态模型研究，3D 表面跟踪器的感兴趣区域 (ROI) 表面大小大于 1000 个顶点时，其均方根误差 (RMSE) 约为 0.30 毫米。虽然，3D 表面系统的处理周期 (1/fps) 被发现与 ROI 顶点数量呈线性增加，但只要 ROI 足够大且包含用于注册的特征，跟踪精度就被发现与 ROI 大小无关。对于人类受试者，3D 表面跟踪和 IR 标记跟踪模式之间的 RMSE 为 0.22 毫米（x 轴）、0.44 毫米（y 轴）、0.27 毫米（z 轴）、0.29°（绕 x 轴）、0.18°（绕 y 轴）和 0.15°（绕 z 轴）。
3D 表面成像有可能提供亚毫米级别的头部运动跟踪。这是前提是可以进行高度准确的相机到 LINAC 参考框架校准，并且参考 ROI 具有足够的大小并且包含用于注册的合适的表面特征。
