1529799 Radiography EMI Ltd 31 Oct 1975 [13 Nov 1974] 49074/74 Heading H4F A computed tomography scanner in which a fan-shaped spread of radiation beams 14 is subject to angular scanning has means for giving the radiation source a counter-rotation relative to the detectors, e.g. by scanning an electron beam along an elongated anode 13 of an X-ray tube 10, in a scan and flyback mode so that during each scan period of the counter-rotation each beam is maintained parallel to its original direction relative to a body under examination. The invention can also be applied to a scanner using lateral and angular scanning, Fig. 6 (not shown) thus permitting continuous rather than incremental angular scanning. An arrangement is described with reference to Fig. 7 (not shown) in which a cylindrical array of collimating slits is disposed between a rotating source-detector combination, the collimating slits being rotated in the opposite direction to the source and detectors.
展开▼
