In order to provide a method of generating an accurate contour image from projection data of a nuclear medicine image of a subject,contour information is extracted from nuclear medicine projection data on a subject not subjected to a scattering correction and an absorption correction by performing a pixel value binarization processing based on a threshold scheme. If necessary, an interpolation processing is performed before reconstructing an image through an image reconstruction processing. Based on the reconstructed image, a second binarization processing is performed to generate a contour image.
