1. A method of constructing multiple tomographic images of a subject, comprising: irradiating X-rays onto a subject by operation of an X-ray source; detecting the X-rays that pass through the subject by an X-ray imaging CCD device; providing an imaging system by oppositely arranging and fixing the X-ray imaging device and the X-ray source at a certain distance, centered on the subject; revolving said imaging system about an axis centered on the subject; storing image information being obtained by the X-ray imaging device with a single X-ray radiography operation into a large-capacity frame image storage device as a frame image; digital-processing respective frame images extracted from the large-capacity frame image storage device to form panoramic images; storing the panoramic images in a large-capacity processed image storage device; displaying the panoramic images stored in the large-capacity processed image storage device; arraying a certain frame image taken out of the panoramic images stored in the large-capacity processed image storage device onto a circular arc arrangement, by linear-interpolating the pixel value with the area ratio per circular arc shaped square cell elements across plural pixels; performing a polar coordinate transformation sequentially with respect to each frame image by using the angle rotated while obtaining said each frame image as a unit angle; and adding the frame images sequentially by shifting every unit angle to construct a tomographic image on the radius positioned at the desired location.