一般醫學影像脊椎手術導引系統需使用電腦斷層掃描重建的脊椎模型，搭配光學式導航系統或機器臂進行經皮影像導引手術。這些系統需要專業工程師在手術房內架設，且所需的術前電腦斷層影像易造成醫師或病患潛在輻射風險。若影像導引系統使用的三維脊椎模型可用術中拍攝的X光重建，就可減少病患暴露的輻射劑量，並獲得術中各椎節相對位置。因此，本研究提出一個以兩張X光重建腰椎模型的方法。
首先在兩張X光上設定腰椎的特徵點，並設為用來腰椎樣板變形的目標。形變過程簡化為augmented Lagrangian最佳化方法的最小化問題。利用變形的腰椎椎節模型評估變形方法的優劣，用以評估X光二維逆向建構的三維椎節模型與電腦斷層重建的標準模型間的表面誤差。
評估結果顯示，重建無病變和有病變腰椎的平均誤差分別為1.27 mm和1.50 mm。誤差結果與其它以樣板模型重建的文獻結果雷同。本研究所提出的方法可替代用於脊椎手術中影像導引的數位腰椎模型，有機會應用在手術規劃或術中導航系統中。

Vertebrae models from CT imaging are extensively used in image-guided surgical systems, which, coupled with navigation system or with robots, are able to deliver percutaneous orthopaedic operations with minimum risks. These systems require engineers to setup before
the operation, and while pre-operative CT scans may expose excess radiation to the patient, it is the necessary risk to take considering the significance of the operation. Generation of vertebrae models from intra-operative X-rays for image-guided systems can reduce adiation
exposure to the patient, the surgeons can obtain information on the vertebrae’s relative positions during the operation. Therefore, we proposed a lumbar vertebrae reconstruction method from biplanar X-rays.
Non-stereo-corresponding vertebral landmarks on both X-rays were identified as the targets for deforming a set of template vertebrae, and the deformation was formulated as a minimisation problem, which was solved using the augmented Lagrangian method. The deformation method was evaluated using deformed lumbar vertebrae models; the errors in between the X-ray-constructed vertebrae and the digital vertebrae generated from CT imaging were calculated as well.
The evaluation yielded mean errors of 1.27 mm and 1.50 mm on normal digital vertebrae and deformed vertebrae models, respectively; the outcomes were comparable to other template-model-based methods. The proposed method is a viable alternative to provide digital lumbar to be used in image-guided systems, where the models can be used as a visual reference in surgical planning and image-guided applications.

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