1. An apparatus for processing a medical image, the apparatus comprising: 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 configured to monitor whether a malfunction occurs among the plurality of processors, and configured to, when the malfunction occurs in a processor assigned to the first operation, reassign the first operation to at least one of the plurality of processors such that a number of the plurality of processors assigned to the second operation is reduced.