Patent Number: 047440996
Section: description

DETAILED DESCRIPTION In the drawing an x-ray diagnostic apparatus for the preparation of mamma radiographs is illustrated including an x-ray source 1 and a support table 2 for the radiography subject 3. Serving the purpose of compression of the radiography subject 3 is a compression device comprising a compression localizer 4 which is mounted on a compression carriage 5 and which is pressed by means of an electromotor 6 against the radiography subject 3. When the localizer engages the radiography subject 3 and attains a specific specified compression force, the motor 6 is shut off. With the compression localizer 4 resting against the radiography subject 3, a spring 7 is tensioned corresponding to the respective compression force, which spring is secured to one end of a lever 8 which is pivotally mounted about a shaft 9, and which, at the other end, supports the compression localizer 4. The spring 7, in conjunction with an actual value transducer 10, forms an electric signal corresponding to the compression force exerted by the localizer 4. In the illustrated apparatus, in addition, the respective compression path s is detected by a path length transducer 11 and converted into an electric signal. The transducer may be coupled wtih the output drive train driven by motor 6 as indicated by the dash line 11a. The motor 6 (which is secured to carrage 5) positions the carriage 5 via a toothed wheel 12 which has rolling engagement with a fixedly mounted toothed rack 13 which is fixed relative to support table 2. The actual value signals for the compression force and compression paths are supplied via lines 14a and 15a to inputs 14 and 15 of the density computer 16 which determines therefrom the density of the radiography subject 3 and hence the respectively required radiation filter. A signal corresponding to the required filter is connected to the output 17 of the density computer 16. The provided radiation filters can be arranged in the manner described in U.S. Pat. No. 3,976,889 on a disc 19 rotatably mounted in an eccentric fashion relative to the central ray of the x-radiation 18. In order to rotate the disc 19 an electromotor 20 is provided which forms an actual value signal on the line 21 which corresponds to the filter respectively shifted into the ray path 18 (in the example a filter 19a is shown in the operating position). This actual value signal on the line 21 is compared with the desired value signal on the line 17. If the filter disposed in the ray path does not agree with the required filter, an amplifier 22 will deliver a signal at its output 23 which switches on the motor 20 until the signals on the lines 17 and 21 correspond. Instead of the detection of the compression force and of the compression path, in the case of simple apparatus with a fixedly adjusted compression force, it can be sufficient to detect only the respective compression path. The density signal on the line 17 can also be supplied via an interface to the x-ray high voltage generator supplying the x-ray source 1 and in this fashion an automatic adjustment of the x-ray tube voltage can take place as described, for example, in U.S. Pat. No. 3,991,314. It will be apparent that many modifications and variations may be made without departing from the scope of the teachings and concepts of the present invention.