An x-ray imaging system is disclosed, where one example of such a system includes a frame or other structure to which a modular cooling unit of the x-ray imaging system is attached. The modular cooling unit includes a radiator, configured for fluid communication with an x-ray tube housing, as well as one or more fans configured to cause a flow of air to pass through the radiator. In this example, the x-ray imaging system further includes a detector array arranged to receive x-rays generated by an x-ray tube insert disposed within the x-ray tube housing. In operation, the air flow caused by the fans of the modular cooling unit removes heat from coolant flowing out of the x-ray tube housing and through the radiator.