Patent Number: 046413359
Section: abstract

A primary-beam collimator for a stereo radiographic x-ray diagnostic installation has an x-ray tube with dual focal points (F1, F2) arranged at a distance from each other. Shutter leaves (1a, 1b, 2a, 2b, 3a, 3b, 4a, 4b) are provided, and adjustable so that two beam pyramids (I from focal point F1, and II from focal point F2) can be individually controlled. Two internal shutter leaves (4a, 4b) are provided for restricting the beam in planes perpendicular to the stereo base F1-F2. These are adjustable between two external shutter leaves--each in the direction of its corresponding external shutter leaf. The internal shutter leaves (4a, 4b) are constructed so that, when adjusted to their external positions, they permit the emission of a central beam-pyramid from a central focal point (FN) and, together with the external shutter leaves (2a, 2b), they close the external shutter openings.