Abstract: A tomography apparatus has an annular channel and at least one ventilation element for the purpose of drawing off an air current flowing through the annular channel. The ventilation element contains an intake window that is located in the annular channel for the purpose of drawing off at least a portion of the air current. In order to obtain an even flow profile at an output window of the ventilation element, the intake window has a greater effective intake cross-section at both sides than at the middle. By such evening the flow profile at the output window, turbulence and air current interruptions of the air can be generally avoided, such that when operating the tomography apparatus, disrupting acoustic emissions may be reduced, or a higher air flow and thereby a greater cooling effect may be obtained.