After photographing images (80a, 80b, 80c&mldr80n) that include a marker (M), the portions of the marker (M) are extracted to obtain template images (81a, 81b, 81c&mldr81n). When starting treatment on a subject (57), fluoroscopy is carried out on a region that includes the marker (M). Template matching is then performed using the multiple template images (81a, 81b, 81c&mldr81n) on the region (83) that includes the marker (M) in an image (82) which is photographed at regular intervals. That is, all of the multiple template images (81a, 81b, 81c&mldr81n) are sequentially matched against the region (83) that includes the marker (M) in the image (82) which is photographed at regular intervals.
