An organ region extracting section that extracts at least one organ region from a three dimensional image of a subject a directional data obtaining section that obtains directional data of the subject based on one of the position of the organ region within the body of the subject and the shape of the organ region a stage region extracting section that extracts a region of a stage on which the subject is placed from the three dimensional image and a posture data obtaining section that obtains posture data of the subject on the stage, based on the region of the stage and the directional data of the subject are provided.
