A cooler (20) that circulates cooling fluid to cool an X-ray tube (10), and that comprises a circulation unit (22) that has a first end unit (27) in which an outlet to deliver the cooling fluid is formed, and a second end unit (28) in which an inlet is formed, and takes in the cooling fluid from the inlet to cool thus taken-in cooling fluid and deliver the cooling fluid to the outlet, and an expansion mechanism (60) that has a vessel (61) which is attached to the circulation unit and which has an opening (64) through which cooling fluid flowing in the circulation unit comes in and goes out, and a bellows (63) that divides the inside of the vessel into a first chamber (R3) communicating with the opening and a second chamber (R4), wherein the first end unit and the second end unit are detachably coupled to the X-ray tube, and are closed when being uncoupled from the X-ray tube, and the expansion mechanism can be switched between a first state in which coming in and going out of ambient atmosphere to and from the second chamber is shut off to restrict coming in and going out of the cooling fluid to and from the first chamber, and a second state in which coming in and going out of ambient atmosphere to and from the second chamber is released to allow coming in and going out of the cooling fluid to and from the first chamber.L’invention concerne un dispositif de refroidissement (20) qui fait circuler un fluide de refroidissement destiné à refroidir un tube à rayons X (10), et qui comprend un module de circulation (22) possédant un premier module d’extrémité (27) dans lequel est ménagée une sortie de décharge du fluide de refroidissement, et un deuxième module d’extrémité (28) dans lequel est ménagée une entrée d’admission du fluide de refroidissement afin de le refroidir et de l’acheminer vers la sortie, et un mécanisme de détente (60) comportant une cuve (61) fixée au module de circulation et comportant une ouverture (64) par laquelle entre et sort le fluide de refroidi
