二維醫學影像X光普遍被使用於骨科術前診斷，另外由於C-arm設備的高機動性高，能在手術中隨時更新影像，因此於骨科手術中經常藉由C-arm影像輔助手術進行。然而在手術過程中，醫師須憑藉本身臨床經驗規劃手術路徑以進行手術，為了要精準的定位，一次手術常需照射數十張的C-arm影像，造成醫護人員長期暴露在具有放射線的環境下，對健康影響甚大。本研究發展一套以三維CT影像灰階為資料，模擬X光與C-arm二維影像技術，其核心演算法則是以光線投射法及立體渲染法為主，以顯示虛擬二維影像；為了提高計算效率與影像擬真度，本研究改良原始演算方式，減少不必要的資料計算與加入多執行緒處理，達到減少模擬計算時間；另外，利用分區域線性改變原始CT影像灰階後再進行影像模擬，根據調整線性方程式參數以模擬出相似於真實二維影像，並觀察真實二維影像特徵，由特徵判斷虛擬影像與真實影像相似度，找出最佳模擬結果可應用於後續之研究。 Two-dimensional X-ray images are commonly used for the pr-surgical diagnosis of orthopedic diseases, while two-dimensional C-arm images are typically employed for detecting the status of the implants and surgical tools during the surgery. Over radiation is always a problem in current surgical process as taking the C-arm images is a trial-and-error process. Even for an experienced surgeon, he must face the risk of receiving high dose of radiation as the radiation is accumulated day by day, year by year. In this study, a virtual X-ray and C-arm images simulation technique is developed for providing a way of training without using real X-ray or C-arm images. The ray casting and volume rendering methods are employed for the generation of the virtual images from the CT data. Two important issues affecting the feasibility of the virtual images are the similarity to real images and the computational efficiency. Approximate algorithms are presented to deal with such tissues. Several examples, including real X-ray images and C-ram images on human body and prosthesis, respectively, are presented to evaluate the feasibility of the proposed virtual simulation technique. In addition, extensive parametric study is also conducted to acquire suitable combination of parameters for real applications.
