Patent Number: 
Section: claims

1. An X-ray CT scanner for reconstructing a CT image of a subject, comprising:an X-ray source configured to emit an X-ray beam;an X-ray detector having a plurality of detecting elements and configured to detect X-rays transmitted through the subject;a reconstructing unit configured to reconstruct the CT image based on an output of the X-ray detector;a determining unit configured to allow a user to set a thickness of the X-ray beam to an arbitrary integral multiple of a pitch of the detecting elements, as measured in a body axis direction of the subject, by graphically manipulating a frame representing the ends of the X-ray beam;a control unit configured to generate a calibration data file used to correct projection data obtained using the set X-ray beam thickness, from stored calibration data corresponding to predetermined X-ray beam thicknesses other than the set X-ray beam thickness; anda display unit configured to display a scanogram based on the reconstructed CT image, and to graphically display on the scanogram, the frame representing the ends of the X-ray beam set by the determining unit. 2. The scanner according to claim 1, wherein the display unit is configured to display, on the scanogram, information regarding a scanning range covered by a helical scan. 3. The scanner according to claim 1, wherein the display unit is configured to display a cursor indicating a center of an X-ray beam and a cursor indicating ends of an X-ray beam. 4. The X-ray CT scanner of claim 1, wherein the control unit is configured to generate the calibration data file by interpolation using the stored calibration data and the set X-ray beam thickness. 5. The X-ray CT scanner of claim 1, wherein the control unit is configured to generate the calibration data file by extrapolation using the stored calibration data and the set X-ray beam thickness. 6. An X-ray CT scanner, comprising:an X-ray tube configured to emit X-rays;an X-ray detector having a plurality of detecting elements and configured to detect X-rays transmitted through a subject;a scanogram generating unit configured to generate scanogram data based on an output of the X-ray detector;an image reconstructing unit configured to reconstruct tomographic data based on an output of the X-ray detector;a display unit;a screen generating unit configured to generate data of an X-ray beam thickness setting support screen, which is to be displayed on the display unit, the X-ray beam thickness setting support screen including the scanogram and a frame including both ends of an X-ray beam obtained in accordance with a thickness of the X-ray beam arranged on the scanogram;a manipulating unit configured to allow a user to graphically manipulate a size of the frame so as to set the thickness of the X-ray beam to an arbitrary integral multiple of a pitch of the detecting elements; anda control unit configured to generate a calibration data file used to correct projection data obtained using the set X-ray beam thickness, from stored calibration data corresponding to predetermined X-ray beam thicknesses other than the set X-ray beam thickness. 7. The X-ray CT scanner of claim 6, wherein the display unit is configured to display, on the scanogram, information regarding a scanning range covered by a helical scan. 8. The X-ray CT scanner of claim 6, wherein the display unit is configured to display a cursor indicating a center of an X-ray beam and a cursor indicating ends of an X-ray beam.