Patent Number: 053496256
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to an x-ray diagnostics installation of a type suitable for conducting peripheral angiography examinations. 2. Description of the Prior Art X-ray diagnostics installations for conducting peripheral angiography examinations, i.e., of blood vessels in the extremities of a patient, generally include a pick-up unit composed of a radiation transmitter and radiation receiver, and a support means for an examination subject, with the pick-up unit and the support means being spatially adjustable as well as adjustable relative to one another via suitable means. The radiation transmitter can be supplied with energy via a control means, causing the emission of a ray beam. If the radiation receiver is executed as an image intensifier, it is followed by a video chain, so that an image of an examination region can be produced. A gating device is provided in the beam path of the ray beam with which the emitted ray beam can be gated onto the examination region. An automatic exposure unit controls the energy supply of the radiation transmitter such that a radiation shadowgram produced during transirradiation of the examination subject can be converted into a visible, easily interpreted image. If the radiation receiver is an x-ray film changer, it can be provided with an automatic exposure unit to insure that every exposure has the correct degree of blackening. A peripheral angiography examination requires complicated and time-consuming programming measures for producing the exposure sequence, for the exact setting of the support means and diaphragm system as well as for defining the required range of displacement of the pick-up unit or of the support means. To this end, in conventional systems the patient, support means, pick-up unit, diaphragm system and automatic exposure unit are configured and optimized for the successive exposures with respect to the image quality, the patient position and the examination region. This typically results in physical stress on the patient is thus considerable; moreover, the number of possible examinations that can be carried out daily is reduced. German Patent 39 19 473 discloses an x-ray diagnostics installation for angiography, wherein a standard pre-setting of the x-ray dose, gating of the x-radiation, as well as the number and direction of the relative dislocations of the patient support and pick-up means ensue on the basis of a program for every exposure of a body section to be examined. SUMMARY OF THE INVENTION It is an object of the present invention to provide an x-ray diagnostics installation for conducting peripheral angiography examinations wherein the physical stress on the patient is reduced when producing the exposure sequence and with which the number of examinations possible on a daily basis is increased. This object is achieved in accordance with the principles of the present invention in a peripheral angiography system having a control unit which includes an arithmetic unit that undertakes a calculation for pre-setting one or more system components matched to the examination subject, based on subject-related data (size, weight, shape, etc.). The advantage of the invention is that an optimized examination program can thus be produced for the patient, so that the time consumed for producing the exposure sequence is greatly reduced. The physical stress on the patient is likewise reduced due to the low time expenditure. Mis-adjustments of the pick-up unit and support device are thus avoided, so that the radiation stress on the patient as well as stressing of the patient by injections of contrast agent are reduced. Preferably, for further time-saving and reduction of the stress on the patient, the arithmetic unit calculates the diaphragm setting required for every exposure, and/or calculates the parameters of the radiation transmitter required for every exposure, and/or takes the format of the radiation receiver as well as the focus-to subject and focus-to radiation receiver spacing into consideration in making the calculation. The arithmetic unit may be followed by a display means for displaying the contour of the examination subject, the image size in the subject plane, the diaphragm settings and the radiation field with reference to the examination subject for every exposure position.