The automated segmentation of the prostate region in CT images is required by the computer-aided diagnosis and therapeutic radiology. The purpose of this study is to develop an automated scheme for estimating the location (center point) of the prostate gland in torso X-ray CT images. The proposed scheme consists of four processing steps. At first, a prostate gland centroid is extracted manually, and pelvis landmarks are extracted automatically on training dataset. Second, based on the pelvis landmarks, each pelvis shape is normalized. Third, a prostate gland centroid model is constructed by the principal component analysis. Finally, a prostate gland model is applied to a target case, and the center point of prostate gland is estimated. The proposed scheme was applied to 20 CT cases. We found the proposed scheme could estimate the location of the prostate gland with the mean error (3-D distance from the grand truth) of 2.6mm. This scheme was used for prostate gland segmentation using a simple sphere model. From experimental results, the effect of the proposed scheme for estimating the location of the prostate gland was confirmed.
