A novel method for accelerating the visualisation process used in virtual colonoscopy

Virtual colonoscopy is a non-invasive technique with the potential for wide application in the early detection of colorectal cancer. Unfortunately, to be clinically useful, it is reliant on the rapid visualisation of three-dimensional (3D) data using personal computers. This is not possible using current visualisation techniques. We present a novel method to accelerate volume rendering via ray casting as used in virtual colonoscopy. The method uses a space leaping technique in which the space inside the colon is approximated by maximal spheres constructed using the distance transform of the cavity. These spheres enable subsequent ray casting to traverse the space in an efficient way. The method has been implemented on a personal computer and is approximately 2.9 times faster when compared to the usual ray casting method for virtual colonoscopy. Potential uses of this method extend beyond virtual colonoscopy to all endoscopic applications and indeed any volume rendering application involving voxels with uniform properties.