Three dimensional display computer tomography for the oral and maxillo-facial region

When diagnosing diseases in the oral and maxillofacial region, radiographic diagnosis plays an important part. However, the problem encountered is the difficulty to image three dimensional constructions from conventional X-rays. Recent improvements in medical imaging process based on advanced computer technology have facilitated not only more precise diagnosis of diseases but also improved treatment for diseases in the oral and maxillofacial region. The purpose of this report is to evaluate the various aspects and functions of three dimensional display by means of computerized tomography in oral and maxillofacial regions. We have clinically applied this method to fifteen patients. The diagnosis using three dimensional display is superior that of X-ray display due to the following points: The entire display can be directly observed in its three dimensions. Dislocation and defect of the bone can be detected clearly. The display can be further observed by changing to optional directions, as well as cross sections. The data can be collected by observers with less variation of interpretation between them. Not only can distance be measured but volume and space can also be computed. On the other hand, there are the following problems for further consideration of the three dimensional display. When exposure times increase, exposure dose also increases. It takes more time to take three dimensional displays, therefore it is difficult to keep the body stationary. The artifact will occur when metals are presented in part of exposure fields. When the threshold does not set properly, the display can not be shown precisely. (author)