Abstract: An X-ray diagnostic installation includes an X-ray source and a radiation receiver and a digital imaging processing system, the digital imaging processing system including a computer which evaluates an X-ray image of a phantom by identifying visible details in the X-ray image of the phantom. The computer employs these identified visible details to automatically construct a contrast-detail graph of the phantom. The computer thus undertakes an automatic judgment of the imaging quality, without the need for a trained observer.

Abstract: An x-ray examination installation includes an x-ray source for irradiating an examination subject with x-rays, and an automatic exposure unit having a radiation detector composed of a matrix of detector elements. Only the output signals of specified detector elements, which define the measuring field within which an optimum exposure should ensue, are utilized for generating a signal which is then supplied to the x-ray source for controlling the exposure dose. The automatic exposure unit is operated according to a method wherein a distribution of the grayscale values in a test image is first calculated, and subsequently the main image is produced with the previously-calculated distribution of grayscale values superimposed in the main image.

Abstract: An x-ray apparatus includes an x-ray tube having a focus, the x-ray tube being contained in a housing and the housing having a mechanical distance-measuring device attache thereto. The mechanical distance-measuring device is suitable for obtaining a measured value which exactly corresponds to the focus-to-skin distance for all types of examinations. The mechanical distance-measuring device, which may be a tape measure, is connected to an electrical signal generator which converts the mechanically measured value into a corresponding electrical signal.

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: A detector for the image brightness which is present at the output screen of an x-ray image intensifier is formed by a combination of individual detector elements, the detector elements having different shapes and/or sizes. The detector elements in combination form a matrix which enables an optimum selection of a desired measurement field by selecting defined combinations of individual detector elements.

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 automatic x-ray exposure unit has first and second radiation detectors disposed sequentially and in registry in the direction of radiation propagation following the examination space. Each radiation detector is formed by a matrix of detector elements, also in registry. The detector elements are connected to a computer which calculates the quotient of the signals of each pair of detector elements in the first and second radiation detectors which are in registry. Those pairs of detector elements having a signal quotient which is above a predetermined threshold are automatically taken into consideration for selecting the measuring field for an x-ray exposure.

Abstract: An x-ray diagnostics generator which includes a rotating anode x-ray tube includes circuitry for setting the speed of rotation of the anode dependent on exposure parameters. At particular rotational speeds, the motor bearing for the rotating anode is subject to mechanical resonances, causing vibrations which can damage the bearing. A vibration detector is provided in mechanical contact with the x-ray tube, and when vibrations due to such mechanical resonances are sensed, a signal is provided from the detector to a processor which automatically slightly alters the rotational speed.

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 having an image intensifier video chain which back-projects a region of primary medical interest within an x-ray image into the overall video image is provided with fiber optics and opto-electronic transducers which are actuated by a switching bank in accordance with the desired shape and position of the region of primary interest. The transducers and switching arrangment can be removed, so that the output image from the x-ray image intensifier can be viewed at the output side of the fiber optics.

Abstract: A medical examination system includes components for generating an internal image of a patient, such as an x-ray image, and components for generating an image of the external surface of at least a portion of the patient. The signals obtained from the surface scan of the patient are used to control the positioning of other components, such as the patient support and/or the primary radiation diaphragm. The internal and surface images can be compared to achieve precise positioning of the patient and/or a setting of the primary radiation diaphragm to avoid blooming.

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: The invention relates to a diagnostic radiology setup with means for suppressing stray radiation and with an image intensifier television chain with image storing means. There is provided a perforated diaphragm of radiation-absorbing material near the tube, which diaphragm can be introduced into the ray path selectively. Two image memories for an X-ray picture with a diaphragm and an X-ray picture without a diaphragm and an image processing system serve for comparing the image information of the two X-ray pictures to determine and eliminate the stray radiation component.

Abstract: In an exemplary embodiment, two radiation detectors are arranged behind the radiography subject. One of the detectors is covered by a radiation filter. A different radiation attenuation along the radiation paths of the respective detectors thereby takes place, so that, through division of the output signals of the detectors, a quotient signal can be obtained which corresponds to the radiation transparency of the radiography subject.

Abstract: A pinhole camera forms an image of the optical focal spot of an x-ray tube on a radiation-electrical transducer comprising an intensifier foil and a matrix of photo-sensitive detectors. A processing circuit including an adjustable amplitude selector selects detector output signals for transmission to a video monitor. A calibrated measuring grid can be superimposed on the focal spot image on the monitor.

Abstract: In an exemplary embodiment, two radiation detectors are present which are covered on their inlet sides for the radiation by two x-ray filters of different absorption. A divider divides the two output signals of the radiation detectors so that its output signal is a measure of the time variation of x-ray tube voltage during an exposure. The output signal of the divider is supplied to a time measurement circuit which provides a measure of the exposure time during which the x-ray tube voltage is greater than or equal to a predetermined value.

Abstract: In an exemplary embodiment, a control loop for the x-ray tube current is present which adjusts the x-ray tube current to a value which is a function of the exposure time and the selected mAs-product. In order that deviations of the x-ray tube voltage from a desired value can be controlled via the x-ray tube current, but that the mean value of the x-ray tube current can nevertheless be kept constant, a phase angle control device, arranged in the primary circuit of the high voltage transformer, can be present as the regulating unit for the mean value of the x-ray tube current. As controller for the x-ray tube voltage, a circuit for the adjustment of the filament current of the x-ray tube can be provided.

Abstract: In order to regulate the dose rate, the pulse-pause ratio of the inverter is changed. For this purpose, the regulator can be designed in such manner that, within a predetermined range of the error signal it changes this pulse-pause ratio via a regulating unit and, upon transgression of this range, changes the peak voltage supplied to the inverter via a regulator unit upon constant maintenance of a minimum pulse-pause ratio.

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.