To provide a technique with which dose indices can be managed for body parts in a range to be imaged on a body part-by-body part basis, an X-ray CT apparatus comprises: image producing unit (51) for producing a scout image (10) of a patient; defining unit (52) for defining a range (11) to be imaged in the scout image (10); segmenting unit (53) for segmenting the range (11) to be imaged into two body parts; identifying unit (54) for identifying which one of body parts (12) included in a human body each of the two body parts corresponds to; and calculating unit (55) for calculating a dose index for each of the two body parts.