Abstract: In computerized diagnostic X-ray apparatus data can be provided for a plurality of parallel sectional representations of the body of a patient. If, however, data are required for planes at different orientations in the body it has been usual to realign the body in relation to the apparatus and repeat the examination. It is now proposed to assemble data for inclined planes through the body by reassembly of data for the sections actually examined. The method of achieving this is described, together with a suitable apparatus for the purpose.

Abstract: In a scanning radiographic apparatus, of a type which is particularly suitable for examining inanimate objects, a fixed source and detectors irradiate an object to be examined along a plurality of beam paths. The object is moved in relation to the source and detectors to direct the radiation along a sufficient number of beam paths to allow suitable processing. The object is, for that purpose, mounted on a turntable which can also execute a reciprocating lateral motion relative to the source and detectors.

Abstract: In a medical radiographic apparatus of the kind in which a fan shaped spread of X-rays is subject to lateral and orbital motions, it is disclosed that the orbital step between each lateral scan need not be exactly related to the angular spread of the fan provided that parallel sets of beams are irradiated over a sufficient number of angles to give a proper evaluation of the absorption of the radiation throughout an examined slice. The orbital step may be larger or smaller than the fan angle and may be variable in the course of the scan if desired.

Abstract: A computerized tomographic apparatus is disclosed, as well as a method of operating such apparatus. In circumstances where collimation between the body under examination and the radiation-sensitive detector means is difficult to apply, errors in evaluated absorption coefficients for locations distributed over a cross-sectional slice of the body due to scatter within the slice are reduced by producing a first estimate of the distribution of said absorption coefficients, using this estimate to obtain an indication of the amount of scatter likely to arise from the various locations when irradiated along different paths and using such indication to effect scatter compensation.

Abstract: In computerized tomographic equipment the absorption of penetrating radiation is measured along a plurality of beam paths passing through a region of the body of a patient at different dispositions. Different available processing techniques which may be used with such data require the paths to be distributed in particular ways in relation to the body, for example, in a uniform distribution and in sets of parallel paths. The arrangement of this invention allows the data to be arranged as for paths of different distribution to those for which it was obtained. These paths can be uniform or parallel or both as desired and some may be notional.

Abstract: The data derived from a computerized axial tomographic apparatus in respect of a number of slices through a body are processed to produce a representation of the variation of absorption of X-rays over each slice. The representations are operated upon individually to identify areas which are of reduced interest and/or which are obscuring regions of especial interest. This having been done, the representations for all the slices are correlated to produce a pseudo three-dimensional display of part of the body with the identified areas being displayed with reduced or zero intensity as compared with other areas. Alternatively, the identified and other areas can be represented in different colors.

Abstract: For certain applications it is desired to provide an X-ray tube in which the emitted X-rays can be scanned in relation to the fixed body of the tube. A rotating anode X-ray tube is described in which the periphery of the anode is so shaped that, in the course of rotation, the point of incidence of an electron beam moves relative to the tube as a whole. In response to this the emitted X-rays are similarly moved. Various shapes of anode can be used. In examples described one or more sections of equiangular spirals provide linear X-ray scans, with or without a rapid flyback.

Abstract: In an apparatus for examining a body by means of penetrating radiation a source is arranged to direct radiation through the body and a plurality of detectors are arranged to receive it thereafter. The source and detector are arranged to scan the body to obtain data for use in obtaining a distribution of absorption of the radiation for part of the body. For correction for differences in the relative sensitivities of the detectors they are arranged in pairs to examine radiation along substantially identical paths and for correction for drift each detector is caused to examine a substantially identical path at different times.

Abstract: In a computerized axial tomographic apparatus it is proposed to use, as radiation detectors, alkali halide scintillator crystals cooperating with photodiodes to measure the light output therefrom, or else photodiodes directly sensitive to the radiation passed through the patient. For advantageous operation, especially in regard to drift and rapidity of operation, it is proposed to use the photodiodes photovoltaically and in the so-called "current mode".

Abstract: In a method of constructing a representation of the distribution of absorption in a planar region of a body interpolation is provided, between data signals representing absorption of radiation along parallel paths, to provide signals for an increased number of such paths as required for the processing used. The interpolation is performed by forming differences of second or higher order, subdividing the differences and then combining them by running additions.

Abstract: In a radiographic apparatus, a source of radiation is arranged to scan a planer spread of radiation in a plane (or substantially in a plane) about the body of a patient being examined. A plurality of detector devices is arranged to provide data representing the absorption of the radiation along a plurality of paths within the spread, for different orientations in the plane, for processing to determine a distribution of absorption coefficients for a planar (or substantially planar) slice of the body. The arrangement is such that a predetermined number of the detector devices is irradiated by the spread of radiation at any time, and the actual devices irradiated change progressively as the scan progresses.

Abstract: In a scanning radiographic apparatus in which the object of the scanning is to project the radiation through a substantially planar region of a body along many linear paths, means is provided for monitoring the progress of the scanning and producing timing signals indicative thereof. The timing signals are used to determine, at least in part, the widths of the aforementioned beams and a characteristic, for example the frequency in the event that the signals comprise pulses, is changed to permit the effective width of the paths to be changed. This can be done by means of graticules having differently pitched markings, for example, and each graticule may be associated with a respective range of body sizes.

Abstract: Radiographic apparatus utilizing a plurality of radiation-sensitive detectors to quantify the radiation emerging from a body along respective paths is provided with means for compensating for differences between the sensitivities of the various detectors. The compensating means includes an arrangement for displacing the source of the radiation relative to the detectors and for utilizing output signals obtained from one detector when the source is in its undisplaced and displaced positions respectively to predict what the output of a second detector, closely adjacent the first, should be if the sensitivities of the two detectors were equal. By comparing the prediction with the actual output signal provided by the second detector, differences in sensitivity are evaluated and allowed for. A technique for convolving difference signals rather than net signals is also disclosed.

Abstract: For transfer of electrical energy at high voltage between relatively moving parts it is known to use slip rings and cooperating brushes immersed in insulating liquid. A liquid insulated slip ring connection is described, in which one part is caused to pass through a reservoir of insulating liquid to maintain the insulation without complete immersion and consequent rotating liquid seals. In one example the reservoir itself is formed on the moving part and the liquid is distributed by the forces of rotation.

Abstract: In a scanning X-ray machine involving at least rotational movement of a source about an axis, a flexible connection arrangement is provided for electricity, coolant and the like in which a connection handling arrangement includes a guide to form at least one guided loop between fixed and movable parts of the machine and inside the machine cover, the connection being taken in from and returned to the loop with said movement.

Abstract: In an apparatus for examining a body by means of penetrating radiation a source of the radiation and a detector are arranged to orbit about the body. Data obtained from the detector are used to provide a representation of the distribution of absorption in part of the body. To reduce patient movement artefacts in the reconstructed image some of the data are obtained for substantially the same radiation paths through the body, but at different times, and are combined after weighting by complementary factors.

Abstract: In a radiographic apparatus, radiation is projected through a substantially planar region of a body along a plurality of beam paths which are laterally and/or angularly displaced from one another. A detecting arrangement is provided for detecting the radiation emergent from the body along each path. The detecting arrangement comprises a plurality of cells containing a noble gas such as xenon. The radiation is periodically interrupted to allow time for each cell to be scavenged of ions produced by radiation traversing one path before radiation is incident on the same cell from another path.

Abstract: In a radiographic apparatus employing a fan-shaped spread of penetrating radiation the nature of the source can cause the energy spectrum of the radiation to be variable with position in the fan. Means are provided to modify output signals from the apparatus to correct for errors caused by such variations. The modifying factors required can be calculated or can be determined using a phantom body by a method which is described.

Abstract: In an X-ray source for radiographic apparatus of the type known as computerized axial tomography (CAT) scanners it has been suggested to scan a beam of electrons across a target/anode to correspondingly scan a beam of X-rays relative to a patient. The target is inclined to the electrons mean direction to direct the X-rays in another direction. If a ribbon shaped beam of electrons is used then the shape and orientation of the region of contact, of the electrons, changes. It is proposed to preshape and preorientate the electron beam to retain the desired region of contact, and hence the desired X-ray distribution, during the scanning.

Abstract: A positioning and supporting arrangement for a patient to be irradiated with penetrating radiation is disclosed. The patient is supported on a curved platter, the curvature of which conforms to the curvature of an arcuate groove formed longitudinally in a table or couch. In order that the platter may be slidably moved along the groove, a suitable drive means therefor is described. Preferably a shroud covers the underside of the platter, the shroud being formed of, or including, material which provides a well defined, consistent coefficient of friction between the platter and the table or couch.