At the end of the nineteenth century, scientists of that time dicovered electromagnetic radiation that was later described as X-ray radiation by Wilhelm Conrad Röntgen and got the name after him. With the discovery of X-rays, also started development of radiology as a branch of medicine that deals with use of different kinds of radiations for diagnosing and treatment of various illnesses. Develoment of science in medicine led to development of technology of X-rays and medical technology. Frequent improvement of technology in radiology, devices and appliances brought inevitable needs for maintenance due to reliability and quality of the above mentioned and also to less harmful influence to people and other living creatures. Maintenance of the equipment shows probability for proper function of the equipment at a specific time and provided working conditions. Not until the end of the twentieth century reliability and maintenance takes on significance in all segments of technology so that reliability itself becomes involved in basic technical characteristics of manufacturer, and all that according to demands and needs of buyers. In this work, it is described the procedure of installation, measuring and calibration of new computer tomographic device ' Rotograph Evo 3D', according to technical procedure and instructions given by the manufacturer and can only be installed by authorized person -service technician. Furthermore, there are methods of maintenance of the device for the proper function and protection of patients and staff. In this graduation work, X-ray technology and service technician's approach are explained, starting from the procedure of installation to the approach of maintenance of X-ray dental device and all according to the instructions of the manufacturer.