School of Basic Medical Sciences, Anhui Medical University, Hefei, P.R. China.
Anhui Province Key Laboratory of Medical Physics and Technology, Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Hefei Cancer Hospital, Chinese Academy of Sciences, Hefei, P.R. China.
J Appl Clin Med Phys. 2024 Apr;25(4):e14243. doi: 10.1002/acm2.14243. Epub 2024 Jan 16.
To develop a radiotherapy positioning system based on Point Cloud Registration (PCR) and Augmented Reality (AR), and to verify its feasibility.
The optimal steps of PCR were investigated, and virtual positioning experiments were designed to evaluate its accuracy and speed. AR was implemented by Unity 3D and Vuforia for initial position correction, and PCR for precision registration, to achieve the proposed radiotherapy positioning system. Feasibility of the proposed system was evaluated through phantom positioning tests as well as real human positioning tests. Real human tests involved breath-holding positioning and free-breathing positioning tests. Evaluation metrics included 6 Degree of Freedom (DOF) deviations and Distance (D) errors. Additionally, the interaction between CBCT and the proposed system was envisaged through CBCT and optical cross-source PCR.
Point-to-plane iterative Closest Point (ICP), statistical filtering, uniform down-sampling, and optimal sampling ratio were determined for PCR procedure. In virtual positioning tests, a single registration took only 0.111 s, and the average D error for 15 patients was 0.015 ± 0.029 mm., Errors of phantom tests were at the sub-millimeter level, with an average D error of 0.6 ± 0.2 mm. In the real human positioning tests, the average accuracy of breath-holding positioning was still at the sub-millimeter level, where the errors of X, Y and Z axes were 0.59 ± 0.12 mm, 0.54 ± 0.12 mm, and 0.52 ± 0.09 mm, and the average D error was 0.96 ± 0.22 mm. In the free-breathing positioning, the average errors in X, Y, and Z axes were still less than 1 mm. Although the mean D error was 1.93 ± 0.36 mm, it still falls within a clinically acceptable error margin.
The AR and PCR-guided radiotherapy positioning system enables markerless, radiation-free and high-accuracy positioning, which is feasible in real-world scenarios.
开发一种基于点云配准（PCR）和增强现实（AR）的放射治疗定位系统，并验证其可行性。
研究了 PCR 的最佳步骤，并设计了虚拟定位实验来评估其准确性和速度。AR 通过 Unity 3D 和 Vuforia 实现初始位置校正，通过 PCR 实现精确配准，从而实现所提出的放射治疗定位系统。通过体模定位测试和真人定位测试来评估该系统的可行性。真人测试包括屏气定位和自由呼吸定位测试。评估指标包括 6 自由度（DOF）偏差和距离（D）误差。此外，通过 CBCT 和光学交叉源 PCR 来设想 CBCT 和该系统之间的交互作用。
确定了 PCR 过程中的点到平面迭代最近点（ICP）、统计滤波、均匀下采样和最佳采样比。在虚拟定位测试中，单次配准仅需 0.111s，15 位患者的平均 D 误差为 0.015±0.029mm。体模测试的误差处于亚毫米级，平均 D 误差为 0.6±0.2mm。在真人定位测试中，屏气定位的平均精度仍处于亚毫米级，X、Y 和 Z 轴的误差分别为 0.59±0.12mm、0.54±0.12mm 和 0.52±0.09mm，平均 D 误差为 0.96±0.22mm。在自由呼吸定位中，X、Y 和 Z 轴的平均误差仍小于 1mm。虽然平均 D 误差为 1.93±0.36mm，但仍在临床可接受的误差范围内。
基于 AR 和 PCR 引导的放射治疗定位系统实现了无标记、无辐射和高精度的定位，在实际场景中是可行的。
