Effectiveness of filtering procedure for volume rendering of x-ray CT data

Three-dimensional rendering algorithms are generally categorized as either surface or volume-rendering algorithms. Surface-rendering reveals the surface structure of three-dimensional data, such as X-ray CT and MRI image sets. Volume-rendering allows the internal structure to be seen in addition to the surface structure. Volume rendering relies on the classification of volume elements. This classification consists of two parts; first, to discriminate between the region of organs, bones etc; second, to assign suitable opacities to voxels of each region. Some statistical methods of region discrimination have been reported, but these require large amount of storage and computation. We propose a relatively simple method. It uses as gray level transformation. spatial filtering algorithm, for each tissue type. The method brings not only region discrimination effect but also image processing effect such as noise reduction. We then assign opacities interactively, using a GUI (Graphical User Interface). The effectiveness of the procedure was demonstrated by performing computer simulations with X-ray CT data. (author)