Development of computed panoramic radiography using limited projection data

计算机全景摄影的发展利用有限的投影数据旋转全景摄影可以在一张胶片上拍摄整个颌骨的全景。该系统在牙科诊所的全科医生中很受欢迎。但是，在1998年的第39届日本口腔放射学年会上，我提出了一种利用有限的投影数据进行计算机全景摄影的新方法，但有时会因为脊椎在切牙上出现雾状、变形和鬼影而无法诊断。这种方法将有限的投影数据记录到计算机中。并从数学上证明了新的滤波函数将数据从鬼影和雾中还原出来后是反投影的。然后用这种方法可以重建出无重影、无雾、无变形、无重影的全景图。我利用这一理论开发了全景图重建软件，得到了改进的层析图像。然而，重建时间需要1个多小时。这是临床应用中的一些问题。本研究对软件进行了优化。结果，即使使用个人计算机(奔腾1 GHz)，图像重建时间也减少到约20分钟。

Development of computed panoramic radiography using limited projection data The rotational panoramic radiography can take panoramic view of the whole jaw on the only one film. The system is popular in the general practitioners of dental office. But sometime the image can not be diagnosed because of fog, distortion and ghost images on the incisor by the vertebra.I showed the new method about computed panoramic radiography using limited projection data in 39^<th> Japan oral radiology annual meeting at 1998. The limited projection data is recorded into the computer on this method. And it is proved mathematically that the data is back-projected after reduced from ghost and fog by the new filter function. Then the panoramic view without ghost and fog, distortion and ghost may be reconstructed by this method.I developed the new software for reconstruction of the panoramic view using this theory which give us improved tomogram. However the reconstructing time takes over 1 hour. Which is some problem on the clinical use.In this study, The software was optimized. As a result the image reconstruction time was reduced to about 20 minutes even by using personal computer (Pentium 1GHz).