Improvement of Three-dimensional Standardization Using Oblique Cephalograms and Application to Diagnosis of Mandibular Displacement

作者开发了一种扫描x射线照片并处理其图像的方法，以从斜位头像重建颌面部结构中的三维地标，用于高精度定量测量。(1)将一个铅球附着在干颅骨的每个标记上，并用根管填充剂填充每个侧位，然后使用图像扫描仪扫描颅骨的斜位（左右45°）、正位和侧位颅骨，形成图像文件。上颌骨和下颌骨都是手工鉴定的。(2)利用三维计算程序对地标进行水平检测、原点迁移、三维坐标计算等顺序处理。由于每个测量点的识别难度和误差随所用胶片的不同而不同，因此对四种类型的照片分别设置每个地标处的权重，并用于三维坐标计算。(3)三维显示程序可以通过垂直旋转（±90°）、水平旋转（±180°）、垂直或水平方向的平行平移，从不同角度自由显示计算出的三维坐标值。显示图像也可以从0.62放大或缩小到1.61。为了在操作前后进行比较，可以同时以重叠的形式显示两个三维坐标文件。(4)即使斜位（左右45°）头像难以识别的地标，也可以通过正位和侧位头像准确识别。此外，侧位坐标转换将允许使用常规侧位脑电图进行三维分析。上颌不对称诊断的应用上述方法可提高上颌不对称实际病例的三维显示和线性或角度测量的精度，是诊断和制定治疗计划的有效工具。少

The authors have developed a method of scanning X-ray photographs and processing their images to reconstruct three-dimensional landmarks in a maxillofacial sttucture from oblique cephalograms for high-precision quantitative measurements.1. Developing and Improving Three-dimensional Coordinate Reconstniction by Scanner Input(1)A lead ball was attached to each landmark in a dry skull and each lateral was filled with a root canal filling agent Then oblique (45°right and left), frontal, and lateral cephalograms of the skull were scanned to produce image files using an image scanner After filtering the scanned images using image analysis software, the landmarks at the teeth, skull, and upper and lower maxillary bones were identified manually.(2)The landmarks were processed in order of horizontal detection, origin migration, and three-dimensional coordinate calculation using a three-dimensional calculation program. Since the difficulty and error of identification at each measuring point diff … More er depending on the type of film used, weighting at each landmark was set individually for the four types of photographs and used for the three-dimensional coordinate calculations.(3)A three-dimensional display program permits free display of the calculated three-dimensional coordinate values from different angles by vertical rotation(±90°), horizontal rotaton(±180°), and parallel translation in the vertical or horizontal direction. The display image can also be enlarged or reduced from 0.62 to 1.61. For comparison before and alter an operation, two three-dimensional coordinate files can be displayed simultaneously in an overlapping form.(4)Even landmarks difficult to identify from oblique (45°right and left) cephalograms can be identified accurately using frontal, and lateral cephalograms. In addition, lateral coordinate conversion will allow three-dimensional analysis with conventional lateral cephalograms.2. Application to the Diagnosis of Asymmetric Lower MaxillaThe above method will improve the precision of three-dimensional display and linear or angular measurement in actual cases of asymmetric maxilla and serve as an efficient tool for diagnosis and therapeutic planning. Less