A Method for Generating Virtual Unfolded View of Colon using Spring Model

摘要

Recently, virtual colonoscopy (VC) has received attention as a new colon diagnostic method based on the development of imaging devices. VC is considered a less invasive inspection and reduces diagnosing time. However, because the colon has many folds and its shape is long and convoluted, a physician has to repeatedly change viewpoints and viewing directions many times. We previously proposed a new computer aided diagnosis system for the colon that provided virtual unfolded (VU) and virtual endoscopic (VE) views of the colon. This system enables physicians to observe a large area of the colonic wall on a VU view synchronized with a VE view. Thus a suspicious area on a VU view can be observed in more detail on a VE view. We generated VU views by controlling the ray directions of volume rendering. This method had a problem: rays intersected at the curved areas of the colon because the rays were cast perpendicular to the central path of the colon. Ray intersections caused spurious holes in the VU views. In this paper, we present a method that reduces ray intersections by employing a model that allocates springs between planes perpendicular to the central path. Then plane directions are modified by the spring forces to minimize the total length of the springs. In a drawing process, a VU view is generated by casting rays along the planes. We applied the method to abdominal CT images. Experimental results showed that the method can reduce spurious holes on VU views more than the previous method.