X-RAY COMPUTED TOMOGRAPHY METHOD AND APPARATUS

In order for image data pixel value ranges for several slices to be contained within the same preferred range, an x-ray computed tomography method and apparatus comprises an x-ray source 2 for emitting x-rays toward a subject, an x-ray detector 3 for detecting subject transmission information of the emitted x-rays and control means 15 for controlling the x-ray emission and detection, wherein the control means exerts the control so as to, prior to the tomographic imaging of the subject, produce scout images by fixing the angular position of the x-ray source at two different angular positions and performing the scout imaging of the subject respectively at the angular positions; calculates a scanning condition with reference to the standard deviation of image data based on the area of projection display data, a desired standard deviation of the image data and the pixel value attenuation ratio between the scout images acquired respectively at the two angular positions of the x-ray source; and exerts the control so as to perform the tomographic imaging according to the scanning condition.