1. An apparatus for processing a medical image, the apparatus comprising: a display; an image processor comprising a plurality of processors, each of the plurality of processors being configured to be assigned to one of a first operation having a first priority and a second operation having a second priority lower than the first priority, to reconstruct a cross-sectional image of an object; and a controller, operatively coupled to the display, configured to detect whether a malfunction occurs among the plurality of processors, and configured to, when the malfunction occurs in a processor assigned to the first operation, perform at least one of reassigning the first operation, to the plurality of processors such that a number of the plurality of processors assigned to the first operation is maintained and changing use rate of the plurality of processors assigned to the first operation.