Abstract: In an x-ray diagnostics installation for mammography, an automatic setting of the optimum beam quality ensues in combination with transparency matching. A set of exposure parameters corresponding to different thicknesses of the examination subject is stored in a memory (reference values). At the beginning of an x-ray exposure, a comparator compares the transparency signal (actual value) to the exposure parameters (reference value) interrogated from the memory dependent on the current thickness of the examination subject, and influences the x-ray tube voltage for the purpose of a rated/actual value comparison without interrupting the exposure.

Abstract: An automatic x-ray exposure unit for mammography permits a correction of the mAs product dependent on the subject thickness without the need for obtaining a transparency signal, and thus without the need for the double detector normally needed for that purpose. The automatic x-ray exposure unit permits the correction to be undertaken on site, prior to conducting an actual examination, and thus can be used for film/foil systems, such as customized systems for which no previous transparency data has been obtained. This is accomplished in an automatic x-ray exposure unit where the mAs product is obtained for a fraction (1/n) of the total exposure, and a total exposure value is then obtained by multiplying the fractional value by n. These values are used to generate a characteristic curve, which is stored, for the film/foil system being used. If it is then necessary to switch (adjust) the mAs value due to the subject thickness, this can be done using the stored curve.

Abstract: 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.

Abstract: An x-ray diagnostics installation has an image intensifier/video chain for generating a television image of an examination subject. A portion of the light generated by the output screen of the x-ray image intensifier is directed to a semiconductor detector which monitors the average brightness of the output luminescent screen so that the x-ray dose can be accordingly controlled. The detector has a surface on which the entire output image of the x-ray image intensifier can be imaged, and is connected to a control unit which selects a portion of the semiconductor detector surface which will be used to generate the control signal. The detector includes a diaphragm in the form of a liquid crystal matrix, the matrix being controllable by the control unit to selectively admit or block light to the surface of the semiconductor detector, thereby controlling the regions which will be used to generate the control signal.

Abstract: An x-ray diagnostics installation, of the type suitable for mammography, includes a calculator, such as a computer, which calculates the mean parenchyma dose based on a prescribed relationship from exposure values. The mean parenchyma dose can be read from the computer by a printer to obtain a permanent record.

Abstract: In an illustrated embodiment, a detector having a plurality of measuring fields is provided with a computer circuit for the formation of a difference signal which corresponds to the difference between the greatest and the smallest output signal of the measuring fields, a computer circuit for the formation of a sum signal which corresponds to the sum of the greatest and the smallest output signal of the measuring fields, and a division circuit is connected to provide an output as a function of the difference signal divided by the sum signal, as a measure of contrast over the selected measurement surface. The contrast signal can be utilized to control the duration of an exposure. Further, the contrast signal can be used for an automatic adjustment of the x-ray tube high voltage during an exposure so as to achieve an optimum picture contrast.