Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA.
Med Phys. 2012 Feb;39(2):636-42. doi: 10.1118/1.3675397.
Acquisition of laser range scans of an organ surface has the potential to efficiently provide measurements of geometric changes to soft tissue during a surgical procedure. A laser range scanner design is reported here which has been developed to drive intraoperative updates to conventional image-guided neurosurgery systems.
The scanner is optically-tracked in the operating room with a multiface passive target. The novel design incorporates both the capture of surface geometry (via laser illumination) and color information (via visible light collection) through a single-lens onto the same charge-coupled device (CCD). The accuracy of the geometric data was evaluated by scanning a high-precision phantom and comparing relative distances between landmarks in the scans with the corresponding ground truth (known) distances. The range-of-motion of the scanner with respect to the optical camera was determined by placing the scanner in common operating room configurations while sampling the visibility of the reflective spheres. The tracking accuracy was then analyzed by fixing the scanner and phantom in place, perturbing the optical camera around the scene, and observing variability in scan locations with respect to a tracked pen probe ground truth as the camera tracked the same scene from different positions.
The geometric accuracy test produced a mean error and standard deviation of 0.25 ± 0.40 mm with an RMS error of 0.47 mm. The tracking tests showed that the scanner could be tracked at virtually all desired orientations required in the OR set up, with an overall tracking error and standard deviation of 2.2 ± 1.0 mm with an RMS error of 2.4 mm. There was no discernible difference between any of the three faces on the lasers range scanner (LRS) with regard to tracking accuracy.
A single-lens laser range scanner design was successfully developed and implemented with sufficient scanning and tracking accuracy for image-guided surgery.
获取器官表面的激光距离扫描数据，有望高效地提供手术过程中软组织几何变化的测量值。本文报道了一种激光距离扫描仪的设计，该设计旨在为传统的图像引导神经外科系统提供术中更新。
该扫描仪在手术室中通过多面无源靶标进行光学跟踪。该新型设计通过单个镜头同时采集表面几何形状（通过激光照明）和颜色信息（通过可见光收集）到同一电荷耦合器件（CCD）上。通过扫描高精度的体模并将扫描中的地标之间的相对距离与相应的真实距离（已知）进行比较，评估了几何数据的准确性。通过将扫描仪放置在常见的手术室配置中并采样反射球的可见性，确定了扫描仪相对于光学相机的运动范围。然后，通过固定扫描仪和体模，在场景周围移动光学相机，并观察相对于跟踪笔探针真实位置的扫描位置的变化，分析跟踪精度。
几何精度测试的平均误差和标准偏差为 0.25±0.40mm，均方根误差为 0.47mm。跟踪测试表明，扫描仪几乎可以在手术室设置中所需的任何方向进行跟踪，整体跟踪误差和标准偏差为 2.2±1.0mm，均方根误差为 2.4mm。在跟踪精度方面，激光距离扫描仪（LRS）的三个面之间没有明显差异。
成功开发并实现了一种单镜头激光距离扫描仪设计，具有足够的扫描和跟踪精度，可用于图像引导手术。
