Patent ID: 8744040

Claim:
An X-ray CT apparatus comprising: an X-ray source which emits X-rays while rotating around a subject; a compensation filter which adjusts at least one of output distribution and spectral distribution of the X-rays emitted from the X-ray source to the subject; an X-ray detector which is disposed opposite to the X-ray source with the subject interposed therebetween, rotates together with the X-ray source, and detects an amount of X-rays transmitted through the compensation filter and the subject; an image operation unit which reconstructs a tomographic image of the subject on a basis of the detected amount of X-rays; a display unit which displays the tomographic image; a control unit which controls each of the constituent components; a compensation unit which compensates for deterioration of image quality, which is based on an amount of displacement between a rotation center of the X-ray source and a desired position of the subject, by changing an X-ray tube current modulation pattern indicating a time-series change of emission of the X-rays and/or by moving the position of the subject; and a storage unit which stores a relationship between the amount of displacement and the deterioration of the image quality, the relationship having been experimentally acquired in advance, wherein the compensation unit compensates for the deterioration of image quality, by referring to the relationships stored in the storage unit.