a computed tomography system has a gantry with a rotor side that can be rotated around a system axis during operation , at which at least one x - ray tube is mounted . to cool the at least one x - ray tube a liquid cooling system is equipped with a fluid volume filled with cooling liquid , the fluid volume extends over distances of different sizes from the system axis . the fluid volume is located on the rotor of the gantry and thus is exposed to centrifugal force during operation . to increase pressure in the cooling system , a flexible compensation volume and a movable mass element that rotate with the gantry are provided . the mass element is arranged such that the centrifugal force acting on the mass element during operation causes pressure to be exerted on the cooling liquid .