Introduction & Background: The rapid development of spiral (helical) computed tomography (CT) has resulted in exciting new applications for CT. One of these applications, three-dimensional (3D) CT with volume ren-dering, is now a major area of clinical and academic interest. One of the greatest advantages of spiral CT with 3D volume rendering is that it provides all the necessary information in a single radiologic study (and there-fore at the lowest possible price) in cases that previously required two or more studies. Three-dimensional vol-ume rendering generates clinically accurate and immediately available images from the full CT data set with-out extensive editing. It allows the radiologist and clinician to address specific questions concerning patient care by interactively exploring different aspects of the data set. Three-dimensional images integrate a series of axial CT sections into a form that is often easier to interpret than the sections themselves and can be made to appear similar to other more familiar images such as catheter angiograms. The data are organized into a 3D matrix of volume elements (voxels). The screen of the computer monitor is a 2D-surface composed of discrete picture elements (pixels). Presenting what is stored in memory (ie, floating within the monitor) on a 2D-screen is a challenge, but it is the very problem that 3D reconstruc-tion software has creatively solved. Voxel selection is usually accomplished by projecting lines (rays) through the data set that correspond to the pixel matrix of the desired 2D image. Differences in the images produced with various 3D rendering techniques are the result of variations in how voxels are selected and weighted. In this article, I compare 3D volume rendering of spiral CT data with other rendering techniques (shaded surface display, maximum intensity projection) and present a brief history of 3D volume rendering and discuss the im-plementation of this promising technology in terms of strategies for volume data management, selection of rendering parameters, and features of data display. In addition, I present recent research on the accuracy of the technique in specific medical applications and discuss a number of current clinical applications of 3D volume rendering of spiral CT data. 

Background and Aim: Neurovascular lesions can cause death or disability. Some of them are operable, but surgical approaches are complicated, and proper access to these lesions is crucial. A few of these surgeries occur during the residency educational program, and residents’,experience in operating these lesions may be quite inadequate. Using new technologies like 3D-Reconstruction of vascular lesion images may result in better training and improve residents’,knowledge and understanding of these operations. Methods and Materials/Patients: Four senior neurosurgery residents were enrolled in this study. They were taught to use a 3D image rebuilding program (3D Slicer). They were then asked to rebuild a 3D image of every patient lesion, practice different surgical views, and review anatomical structures around the lesion before surgery Results: All residents mentioned that their knowledge of surgical approaches improved, and they learned more from each operation. Two of them commented that more self-trust during surgeries led to more effective education. Their ability in surgical planning was enhanced too. Attending physicians of these residents believed that this practice improved the residents’,skills and educational quality. Conclusion: New technologies can promote residency educational programs. It seems that working on 3D images of lesions before surgery can boost residents' educational attributes.

Background. Several types of post have been developed for clinical use. A biological dentin post obtained from an extracted tooth eliminates the problems arising from material differences and reduces the fracture rate in teeth undergoing root canal treatment. This study used finite element analysis to compare a biological dentin post with posts made of two different mate-rials. Methods. Three 3D models of the upper central incisor were created, and stainless-steel, glass fiber and biological dentin posts were applied to these models. The restoration of the models was completed by applying a composite as the core structure and a ceramic crown as the superstructure. Using finite element stress analysis in the restoration models, a 100-N force was applied in the vertical and horizontal directions and at a 45º angle, and the suitability of the biological dentin post was evalu-ated by comparing the data. Results. Under the applied forces, the greatest stress accumulation was seen in the models with the stainless steel post. Because the stainless steel post was more rigid, stress forces accumulated on the surface instead of being transmitted to the tooth tissue. In the models with the glass fiber and biological dentin posts, the post material responded to the stratification in tandem with the dental tissue and did not cause excessive stress accumulation on the tooth or post surfaces. Conclusion. The results showed that biological dentin posts prevent the accumulation of stresses that might cause fractures in teeth undergoing root canal treatment. In addition, the physical compatibility and biocompatibility of a biological dentin post with the tooth imply that it is a good alternative to the types of post currently used.