An x-ray diagnostics installation for mammography exposures has a radiation detector for making a radiation measurement used to calculate the average parenchyma dose. The radiation detector is disposed on the support table next to the measurement field in which the mammary gland is disposed, and supplies a signal to a computer corresponding to the measured radiation dose at the detector location. The computer is programmed with the dependency of the average parenchyma dose, with respect to the radiation dose at the location of the radiation detector, and thus the computer generates a value corresponding to the average parenchyma dose, obtained by direct measurement rather than by calculation.