Transcranial magnetic stimulation (TMS) is a noninvasive medical procedure that can modulate brain activity, and it is widely used in neuroscience and neurology research. Compared to manual operators, robots may improve the outcome of TMS due to their superior accuracy and repeatability. However, there has not been a widely accepted standard protocol for performing robotic TMS using fine-segmented brain images, resulting in arbitrary planned angles with respect to the true boundaries of the modulated cortex. Given that the recent study in TMS simulation suggests a noticeable difference in outcomes when using different anatomical details, cortical shape should play a more significant role in deciding the optimal TMS coil pose. In this work, we introduce an image-guided robotic system for TMS that focuses on (1) establishing standardized planning methods and heuristics to define a reference (true zero) for the coil poses and (2) solving the issue that the manual coil placement requires expert hand-eye coordination which often leading to low repeatability of the experiments. To validate the design of our robotic system, a phantom study and a preliminary human subject study were performed. Our results show that the robotic method can half the positional error and improve the rotational accuracy by up to two orders of magnitude. The accuracy is proven to be repeatable because the standard deviation of multiple trials is lowered by an order of magnitude. The improved actuation accuracy successfully translates to the TMS application, with a higher and more stable induced voltage in magnetic field sensors.

翻译：经颅磁刺激（TMS）是一种可调节脑部活动的无创医疗技术，广泛应用于神经科学与神经病学研究。相较于人工操作，机器人凭借其更高的精度与可重复性，有望提升TMS的治疗效果。然而，目前尚未形成基于精细分割脑图像的机器人TMS标准操作流程，导致刺激方案中线圈位姿相对于目标皮层真实边界的规划角度存在随意性。鉴于近期TMS仿真研究表明不同解剖细节会导致显著的结果差异，皮层形态应在确定最优TMS线圈位姿时发挥更重要的作用。本研究提出一种图像引导的TMS机器人系统，重点聚焦于：（1）建立标准化规划方法与启发式规则，以定义线圈位姿的参考基准（真实零点）；（2）解决人工线圈放置依赖专家手眼协调能力而导致的实验可重复性不足问题。为验证机器人系统的设计，我们开展了体模研究与初步人体试验。结果表明：机器人方法可将位置误差降低50%，并将旋转精度提升高达两个数量级；由于多次试验的标准差降低了一个数量级，该精度被证实具有良好可重复性。改进的驱动精度成功转化为TMS应用优势——磁场传感器中感应电压更高且更稳定。