An X-ray unit according to the invention has a first arrangement (2) that is intended for the contactless and X-ray free measurement of first data of an object (1). A control unit (3) controls, on the basis of the first data of the object, a second arrangement (4) that measures X-ray data of the object by means of X-rays. With such an X-ray unit, first data 5 of the object can be obtained without using X-rays and control of the measurement of the Xray data is made possible, with the result that, data, only a minimum X-ray dose is applied to the object.