Volume Rendering

Many advanced rendering techniques with a particular importance and relevance to the interpretation of Cone Beam CT volumetric dataset can be achieved using the volume rendering projection technique. The basic principle behind this technique is to assign a full spectrum of opacity values ranging from (0% which is totally transparent) to (100% which is totally opaque) to the full spectrum of the voxel intensity values which are encountered along a line which passes through the dataset to the viewer’s eyes.

In other words, each voxel with a a specific attenuation value (expressed in hounsfield units) will be assigned a distinct opacity value ranging from totally black (transparent) to totally white (Opaque). So instead of sampling only the highest voxel value along the projection ray like in (maximum intensity projection) or only the lowest voxel value as in (minimum intensity projection) or taking the average as in (raysum projection), all of the acquired data may be used.

In addition, a color scheme or (mapping) can be applied to the intensity spectrum so that each organ can have a distinct color coding or color label. For instance, soft tissue can be assigned a yellow color while bone is assigned a white color.

Volume rendering is an inherently complicated rendering technique with multiple parameters that can be modified to influence the appearance of the final image. This imposes variability upon which parameter to influence to yield the best outcomes for interpretation.