腹部超音波檢查是腹部臟器疾病檢查常用的儀器,並可協助作穿刺及切片檢查。超音波掃描具有即時性與非傷害性，但二維影像雜訊多，且缺乏空間資訊，醫師需要有足夠的經驗才能據以正確判讀。因此本研究融合病患的超音波影像與電腦斷層影像，讓超音波影像與同方位的電腦斷層影像同步顯示，並在電腦斷層影像重建的三維模型上顯示超音波掃描方位，以協助超音波影像的判讀，進而可發展超音波掃描及影像判讀的訓練系統，提供醫護人員使用。 首先利用程式擷取超音波影像與超音波探頭的空間方位，並使用影像校正器，完成超音波影像的校準。電腦斷層影像與超音波方位對正則是掃描共用的球形標記，輔以疊代最近點(Interactive Closest Point)演算法，計算得到兩影像座標系的方位轉換矩陣。之後將兩影像資料與轉換矩陣，以基於MCV軟體架構開發超音波掃描與影像判讀視覺化軟體，並進行方位對正的誤差評估。 方位校準誤差分別以假體與人體進行實驗評估，並以樣板做比對。假體實驗的誤差與樣板測試相若，約為2至3公釐，符合預期精確度。人體實驗則因缺乏明確特徵可供誤差評估，粗略評估誤差約為1至2公分，推測誤差變大主因為呼吸造成臟器移位。因此偵測與補償呼吸所造成的臟器位移量，應可降低方位校準的誤差。 Ultrasound imaging is a convenient tool for diagnosis of abdominal organ diseases and can be applied to biopsy. Ultrasound imaging is real-time and has no harm to human body. However it has some drawbacks such as images are blurred and lack of spatial information. Physicians need well training and clinic experience to avoid misdiagnosis. This study proposes an image registration method between ultrasound images and CT images, which can be used to develop an ultrasound scan training program for medical staffs. First, ultrasound images and corresponding spatial information are captured by computer program, and then the images are calibrated by using an optic tracker and a calibration phantom with N-type wires. The registration between CT images and US images is done by finding the transformation matrix using spherical markers combined with optimization method – the Iterative Closest Point algorithm. Then, the CT and US images can be fused to build a training program using MCV software architecture. The registration errors can also be assessed in the training program. Registration error assessment experiments were performed with a box phantom, an anthropomorphic phantom, and patients. The errors using the box phantom and anthropomorphic phantom were about 1-2 mm. But the results of patient experiments had an error of 1-2 cm. The possible main factor is liver movement due to respiration which should be compensated.
