Abstract：
Objective.A robotic needle implant device for MR-guided high-dose-rate (HDR) prostate brachytherapy was developed. This study aimed to assess the feasibility and spatial accuracy of HDR brachytherapy using the robotic device, for a single intraprostatic target point.Approach.Five patients were treated from November 2019-June 2022 with the robot. The robot fits a 1.5 T MR scanner and the needle can be shifted and angulated. An intraprocedural MR scan was fused with the diagnostic MR and one preplanned needle position was selected for robotic insertion. The needle entry point and angles were set for a needle tip target point within the intraprostatic target volume. The needle was tapped stepwise towards the target point pneumatically. Final needle position was verified with MR, followed by plan optimization and dose delivery. Any remaining planned needles were inserted manually. Needle tip to geometrical target error (NTG-error) was defined as the deviation of the actual tip position relative to the predefined geometric target point, using MR-coordinates. Needle tip to treatment target error (NTT-error) was defined as the deviation of the actual tip position relative to the treatment target point, using fused MR-images pre- and post-needle implantation taking into account prostate deformation. Difference between NTT-error and NTG-error and fiducial marker shifts indicated prostate movement. For determining prostate deformation, the Jaccard index and prostate volumes were assessed.Main results.The robotic device was able to tap the needle to the planned depth for all patients. Mean robotic procedure duration was 142 min. NTG-error was 3.2 (range 1.1-6.7) mm and NTT-error 4.5 (range 2.6-9.6) mm. Marker displacements were smaller than 3 mm. No treatment-related acute toxicity was reported. Feasibility of needle placement within the prostate was considered adequate.Significance.MR-guided robotic needle insertion is feasible with a mean geometric accuracy of 3.2 mm and <3 mm prostate movement.
摘要：
目的开发一种用于MR引导的高剂量率（HDR）前列腺近距离放射治疗的机器人针植入设备。这项研究旨在评估使用机器人设备进行HDR近距离放射治疗的可行性和空间准确性，单个前列腺内目标点。＆＃xD;方法＆＃xD;从2019年11月至2022年6月，五名患者接受了机器人治疗。机器人适合1.5TMR扫描仪，针可以移动和成角度。将过程中MR扫描与诊断MR融合，并选择一个预先计划的针头位置进行机器人插入。针对前列腺内目标体积内的针尖目标点设置针进入点和角度。将针头逐步气动地朝向目标点轻敲。通过MR验证最终针头位置,其次是计划优化和剂量输送。手动插入任何剩余的计划针。＆＃xD;针尖到几何目标的误差（NTG-误差）被定义为实际尖端位置相对于预定义几何目标点的偏差，使用MR坐标。针尖到治疗目标的误差（NTT误差）定义为实际尖端位置相对于治疗目标点的偏差，在考虑前列腺变形的情况下，使用融合的MR图像。NTT误差和NTG误差之间的差异以及基准标记偏移指示前列腺运动。为了确定前列腺变形，评估Jaccard指数和前列腺体积.＆＃xD;主要结果＆＃xD;机器人设备能够将针头轻敲到所有患者的计划深度。平均机器人程序持续时间为142分钟。NTG误差为3.2（范围1.1-6.7）mm，NTT误差为4.5（范围2.6-9.6）mm。标记位移小于3mm。未报告治疗相关的急性毒性。在前列腺内放置针的可行性被认为是足够的。＆＃xD;意义＆＃xD;MR引导的机器人针插入是可行的，平均几何精度为3.2mm，前列腺运动<3mm。
