Belohlavek Marek, Katayama Minako, Deufel Christopher L
Department of Cardiovascular Medicine, Mayo Clinic College of Medicine and Science, Scottsdale, AZ, USA.
Department of Radiation Oncology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA.
J Contemp Brachytherapy. 2025 Feb;17(1):54-61. doi: 10.5114/jcb.2025.148031. Epub 2025 Feb 27.
This study examined whether sonomicrometry can measure displacements of active ultrasound-tracked needle prototype for prostate brachytherapy application with high linearity, accuracy, and precision as well as triangulate the needle's motion relative to intra-rectal ultrasound probe.
Sonomicrometry detects time-of-flight (ToF) of ultrasound signal transmitted from an active ultrasound-tracked needle (customized with a piezo-electric tracking sensor) to independent sensor. The transmission was tested in water for displacements parallel and perpendicular to the needle axis using distances of up to 35 mm. Three-dimensional (3D) tracking of the active ultrasound-tracked needle utilized a simulated intra-rectal ultrasound probe fitted with 5 piezo-electric sensors, and a sonomicrometry triangulation algorithm was used to measure the distances of the needle from the probe.
Incremental displacements of the active ultrasound-tracked needle were measured by sonomicrometry with strong linearity (R ≥ 0.999), high accuracy (mean difference ≤ 0.55 mm), and precision (1.96 × standard deviation of the mean difference ≤ 0.22 mm) compared with a reference. Sporadic false triggering of ToF detection was eliminated by signal inversion. Acoustic spatial tracking by the off-line triangulation algorithm produced virtual 3D wire meshes, which closely spatially overlapped with the corresponding (ground-truth) video clips of active ultrasound-tracked needle movement at several testing time points.
We introduced an experimental active ultrasound-tracked needle and employed sonomicrometry to measure the needle's displacements and triangulate its spatial position. The measurements and 3D spatial tracking yielded promising results for potential prostate brachytherapy applications. Clinical implementation will necessitate developments of automated triggering, real-time tracking, and a commercially viable acoustic needle design.
本研究旨在探讨超声测距法能否以高线性、准确性和精确性测量用于前列腺近距离治疗的有源超声跟踪针原型的位移，并对针相对于直肠内超声探头的运动进行三角测量。
超声测距法检测从有源超声跟踪针（定制有压电跟踪传感器）发射到独立传感器的超声信号的飞行时间（ToF）。在水中对平行和垂直于针轴的位移进行了测试，位移距离最大为35mm。有源超声跟踪针的三维（3D）跟踪使用了一个装有5个压电传感器的模拟直肠内超声探头，并使用超声测距三角测量算法测量针到探头的距离。
与参考值相比，超声测距法测量有源超声跟踪针的增量位移具有很强的线性（R≥0.999）、高精度（平均差异≤0.55mm）和高精确性（1.96×平均差异的标准偏差≤0.22mm）。通过信号反转消除了ToF检测的偶尔误触发。离线三角测量算法的声学空间跟踪产生了虚拟3D线网，在几个测试时间点上，其在空间上与有源超声跟踪针运动的相应（真实）视频片段紧密重叠。
我们引入了一种实验性的有源超声跟踪针，并采用超声测距法测量针的位移并对其空间位置进行三角测量。这些测量和3D空间跟踪为潜在的前列腺近距离治疗应用产生了有前景的结果。临床应用将需要开发自动触发、实时跟踪和商业上可行的声学针设计。
