Intra-operative ultrasound (US) is a popular imaging modality for its non-radiative and real-time advantages. However, it is still challenging to perform an interventional procedure under two-dimensional (2-D) US image guidance. Accordingly, the trend has been to perform three-dimensional (3-D) US image guidance by equipping the US probe with a spatial position tracking device, which requires accurate probe calibration for determining the spatial position between the B-scan image and the tracked probe. In this report, we propose a novel probe spatial calibration method by developing a calibration phantom combined with the tracking stylus. The calibration phantom is custom-designed to simplify the alignment between the stylus tip and the B-scan image plane. The spatial position of the stylus tip is tracked in real time, and its 2-D image pixel location is extracted and collected simultaneously. Gaussian distribution is used to model the spatial position of the stylus tip and the iterative closest point-based optimization algorithm is used to estimate the spatial transformation that matches these two point sets. Once the probe is calibrated, its trajectory and the B-scan image are collected and used for the volume reconstruction in our freehand 3-D US imaging system. Experimental results demonstrate that the probe calibration approach results in less than 1-mm mean point reconstruction accuracy. It requires less than 5 min for an inexperienced user to complete the probe calibration procedure with minimal training. The mockup test shows that the 3-D images are geometrically correct with 0.28°-angle accuracy and 0.40-mm distance accuracy.

术中超声 (US) 因其非辐射性和实时性优势而成为一种流行的成像方式。然而，在二维 (2-D) US 图像引导下执行介入手术仍然具有挑战性。因此，趋势是通过为 US 探头配备空间位置跟踪设备来执行 3D (3-D) US 图像引导，这需要精确的探头校准以确定 B 扫描图像和被跟踪图像之间的空间位置。探头。在本报告中，我们通过开发与跟踪笔相结合的校准体模，提出了一种新的探针空间校准方法。校准体模是定制设计的，以简化手写笔尖端和 B 扫描图像平面之间的对齐。实时跟踪触控笔尖端的空间位置，并同时提取和收集其二维图像像素位置。使用高斯分布对触控笔尖端的空间位置进行建模，并使用基于迭代最近点的优化算法来估计与这两个点集匹配的空间变换。一旦探头被校准，它的轨迹和 B 扫描图像就会被收集起来，并用于我们手绘 3-D US 成像系统中的体积重建。实验结果表明，探针校准方法导致小于 1 毫米的平均点重建精度。没有经验的用户只需很少的培训即可完成探头校准程序，所需时间不到 5 分钟。模型测试表明，3-D 图像在几何上是正确的，角度精度为 0.28°，距离精度为 0.40 毫米。