An X-ray CT apparatus is provided. The X-ray CT apparatus includes an estimation device configured to estimate a feature quantity that relates to one of image quality and a pixel value of an image obtained by performing an X-ray CT scan on a imaging target under a predetermined scan condition, wherein the feature quantity has a correlative relationship with a dose that is based on data obtained from X-ray imaging performed on the imaging target before a main scan, and a calculation device configured to calculate a dose for the imaging target for a case when an X-ray CT scan is performed under a desired setup scan condition, the dose calculated based on the estimated feature quantity and the correlative relationship between feature quantity and dose.
