A tomography apparatus includes: an X-ray generator which emits X-rays； a controller which determines a first value based on a threshold dosage of the X-rays allowed for a subject and generates an absorbed-dose distribution diagram which indicates a location range of the subject in which, when the X-rays are irradiated to the subject based on an imaging condition, an absorbed dose of the X-ray has the first value； and an indicator showing the absorbed-dose distribution diagram.
