In the last twenty years, the growth and application of industrial CT devices in quality control and product quality optimization has been exponential. Although this is a fairly new method of non-destructive testing, it is used in various spheres of mechanical engineering. However, the measurement uncertainty of such devices has not yet been fully determined and there are various influences on the accuracy of the measurement. One of the causes is the release of heat when generating X - rays is the increase in temperature, which can have significant effects on the accuracy of radiographs recorded on a CT device. For the purpose of a more detailed presentation, this paper analyzes and measures the temperature of the housing of X - ray sources and changes, ie displacements on radiograms. The test was performed at four power levels of the device (10W, 20W, 30W and 40W) and the temperature dependences on the displacements are shown. Graphical representations and explanations of measurement data from all measurements are presented, and the data are connected by mathematical and graphical models for the purpose of better analysis of the influence of temperature on the accuracy of CT devices. The obtained results show a large influence of temperature change on the shift of the radiation source, and thus the shift on the obtained radiograms. In the case of longer recordings, the greater the temperature changes and the greater the shifts. Tests have shown that the power level of the device also affects changes and stability of device operation.