1. A computed tomography (CT) image providing apparatus comprising: a display; and a controller configured to: control the display to display a first type CT image of an object including a region of interest (ROI), and a first list comprising a plurality of second type CT images corresponding to the ROI of the first type CT image and information of the plurality of second type CT images, wherein the first type CT image and the plurality of second type CT images are different from each other with respect to CT processing technique, and the information of the plurality of second type CT images relates to the technique, the plurality of second type CT images are generated by using projection data obtained during scanning for the first type CT image, the ROI of the first type CT image corresponds to a partial region of the first type CT image, and each of the plurality of second type CT images is a partial image corresponding to the ROI of the first type CT image.