超音波影像穿刺取樣是診斷腫瘤良性或惡性的常見方法。以徒手或利用探頭旁加裝導引裝置的穿刺方式並無法解決穿刺針受外力變形所造成的穿刺失誤，且使用導引裝置的穿刺針必須順著超音波掃描面穿刺，限制了在需要避開特定組織時改變穿刺方向的彈性，因此臨床上醫師往往難以執行深層小腫瘤的穿刺取樣。 本研究發展出一套超音波影像輔助穿刺導引系統。藉由磁場定位裝置以及超音波影像定位技術，將超音波影像、腫瘤、穿刺針的空間方位轉換至同一個座標系中，並以即時顯示腫瘤與穿刺針針間相對方位的影像來協助醫師進行穿刺路徑規劃及導引。此外，也設計了一穿刺輔助裝置，利用馬達讓穿刺針等速的旋轉，有效減少穿刺時穿刺針受力變形的現象，並且能夠維持穩定的刺入方向。本研究亦提出以雷射測距儀量測胸口的起伏，據以控制病患憋氣在與影像掃描時的同一呼吸狀態，降低呼吸造成肝組織移位變形，影響穿刺的準確性問題， 實驗以豬肝和五花肉為假體，在系統的導引下進行多次穿刺實驗，結果顯示使用18G的穿刺針穿刺，平均距離誤差為3.17mm，最大誤差為4.38mm；使用21G穿刺針，平均距離誤差為3.36mm，最大誤差為4.62mm。此一系統應可幫助醫師穿刺一公分以上的深層腫瘤。Ultrasonic guided biopsy is the most popular approach to diagnose whether tumor is benign or malignant. However, biopsy by free-hand or using probe-attached guidance device cannot avoid needle deflection and misalignment due to external forces. In addition, the biopsy direction must follow and along the plane of ultrasound image which restrict the flexibility to adjust the needle direction to avoid critic tissues. Therefore, it is hard for physicians to do deep and small tumor biopsy clinically. In this research, an ultrasound-assisted biopsy navigation system has been developed. By using electromagnetic tracking system and ultrasound positioning technology, the positions of ultrasound images, tumors, and biopsy needle are transferred to the same coordinate system. Real-time image display of the relative position of tumor and biopsy needle tip will assist the physician to plan and guide biopsy direction. Moreover, a biopsy assistive device, using a stepping motor to enable the rotation of the needle, is designed to reduce needle deflection due to external forces. To reduce the influence of liver displacement and deformation to biopsy accuracy due to respiration, a Laser Range Finder is applied to measure the ups and downs of the patient’s chest to control the breath status during insertion is identical to that during ultrasound scanning. In the experiments, pork liver and pork belly are applied as biopsy phantoms. The results of several experiments show that the average and maximum distance errors of using 18 Gauge needle are 3.17mm and 4.38mm respectively, while the average and maximum distance errors of using 21 Gauge needle are 3.36mm and 4.62mm respectively. It indicates that the developed system should be able to `assist physicians to biopsy deep tumor with a diameter greater than 1cm.
