A method for preventing overheating of an X-ray apparatus. The method includes controlling an X-ray tube and an X-ray detector which are opposed to each other with a subject between them so as to acquire projection data concerning the subject, estimating quantities of heat dissipated from the X-ray tube and a high-voltage generator that supplies power to the X-ray tube during the acquisition, and optimizing a control parameter, which is used to control the X-ray tube and the high-voltage generator, on the basis of estimates of the quantities of heat dissipated during the acquisition so as to prevent overheat of the X-ray tube and the high-voltage generator.