A system and method for a Computed Tomography (CT) process for calculating a dose of radiation to which an object is expected to be exposed when performing a CT scan on the object is disclosed. The CT apparatus includes a scanner that performs a scout scan on the object； an image processor that acquires image data for the shape of the object based on a scout scan image, compares the acquired image data to pre-stored image data, and selects an image data having greater similarity than predetermined similarity to the acquired image data from among the pre-stored image data； and a controller that calculates a dose of radiation to which the object is expected to be exposed, based on a dose of radiation corresponding to the selected at least one image data, and performs a CT scan on the object based on the calculated dose of radiation.
