Abstract: In a computerized tomographic apparatus in which the requisite absorption data are derived by rotating a source of fanned radiation around a body to be examined and detecting radiation emergent from a cross-sectional slice of the body at many times during the rotation the data, when assembled into sets relating to parallel beam paths through the slice, tends to relate to beam paths which are non-uniformly spaced across the slice. Some techniques for processing such data to produce a representation of the variation of absorption of said radiation over the slice should preferably have said data presented thereto in the form of sets relating to substantially uniformly spaced, parallel beam paths. The application of this invention provides considerably more data then is actually required for the processing so that data relating to beam paths of the required numbers and dispositions can be derived therefrom.

Abstract: A compliant coupling mechaism has a first part (10) connectable to a robot arm (A) and a second part (20) connectable to a robot gripper (G). The mechanism is arranged to allow displacement of the second part relative to first part along a ZZ axis direction, and to allow further relative displacement along and/or about (XX) and (YY) axis directions. A locking device (40) prevents such further relative displacement unless a displacement along the (ZZ) axis direction exceeds a preset amount.

Abstract: In a control system for a robotic gripper a processing circuit (10) controls movement of the gripper (20) on a prearranged path. An article (A) held by gripper (20) comes into contact with the probe member (32) of a "known-down" sensor (30). A support assembly (33), on which the probe member (32) is mounted, is displaced with respect to a base member (31) allowing a continuous, uninhibited movement of the gripper along the path, even after contact has been established. In an alternative arrangement the sensor is mounted on the gripper and establishes contact with an article located at a fixed work station.

Abstract: Disclosed are x-ray machines using fan-beams of x-rays to examine sectional slices of patients and to form detailed x-ray pictures of such slices, and methods of so examining patient slices. A source of a fan-beam of x-radiation, and a system detecting the radiation after it passes through a slice of the patient, rotate around the patient.

Abstract: Apparatus for investigating a part of a body intermediate the extremities thereof by means of X- or .gamma.-radiation is disclosed. The body part is surrounded by a liquid medium; the liquid medium being retained in an enclosure having a tubular inner wall formed of flexible material, and the body part is located within the inner wall. The liquid medium can be pressurized to cause the flexible inner wall to fit intimately the periphery of the body part.

Abstract: In Nuclear Magnetic Resonance (NMR) imaging systems it is known to excite resonance in a slice of a body and to sample the resonance signals in the presence of a field gradient across the slice. The gradient field is pulsed. Where such systems analyse the signal to be for many sets of strips in the slice, each set in a different direction, for analysis by techniques used in computerized tomography (CT) X-ray systems, it is now proposed that the field gradient pulsed should reach a maximum after not more than one third of its total duration to balance the spatial frequency emphasis (FIG. 1e) in the CT processing.

Abstract: In nuclear magnetic resonance (NMR) imaging systems it is known to excite resonance in a slice of a body and then to sample the resonance signals in the presence of a field gradient across the slice. It has been proposed that the signals should be sampled at intervals such that there is equal field integral (for the field gradient) in each interval. It is now proposed to use outputs from two NMR probes in the slice and on opposite sides of the body. The phase difference between the two probes is measured and samples are taken when the phase difference reaches a predetermined value. Preferably the samples are taken when a gate detects zero-crossing of the output of a demodulator providing the phase difference. Two probes only may be rotated around the patient as the field gradient rotates or four may be used, two orthogonally disposed pairs and one or other appropriately weighted output used.

Abstract: In NMR imaging systems a pulsed field gradient may be applied across an excited slice (1) and the resonance signal detected during the field gradient pulse. It has been usual to demodulate the resonance signal at the Larmor frequency for a strip at the center of the slice, at which generally the field gradient has a zero-crossing. It has, however, been proposed to put the zero-crossing outside the slice, still demodulating at the slice Larmor frequency. In this invention demodulation is actually at the frequency for a probe (12) which is necessarily outside the patient. This makes the demodulation independent of errors in a local oscillator frequency. Demodulation may be for a probe effect to give a frequency for a strip outside the slice or the probe may be perpendicular to the gradient to give the zero-crossing frequency.

Abstract: A method of examining a patient with x-rays is described in which x-ray measurements are taken of the attenuation suffered by x-radiation when projected across a cross-sectional slice of a patient's body along each of many substantially linear beam paths and are subjected to compensated back-projective processing to produce an x-ray picture representing the variation of attenuation of the radiation with position over the slice. Beam paths which are next to each other in space are arranged to overlap each other.

Abstract: The invention provides an NMR machine capable of a volume scan. Initial data is provided for a plurality of planes in the body, instead of a plurality of lines as previously, and this is repeated at different positions rotated about an axis parallel to the plane. Convolution processing thus yields data for a matrix of lines parallel to that axis. Further rotation about the z-axis and repetition of the previous analysis at each stage yields data for such matrices of lines at different angles to the z-axis and further convolution processing provides data for a three-dimensional matrix of elements in the body. The last mentioned processing may be done in individual ones of parallel planes.

Abstract: In a computerized tomographic apparatus of the kind in which the performances of different detectors are normalized causing them to receive radiation along substantially similar paths in various overlap zones within a body under examination, the normalization can be adversely affected by the amount of radiation exposure suffered by each detector prior to its receipt of radiation along the paths in the overlap zones. The invention permits such adverse effects to be reduced or eliminated by averaging the electrical signals, produced by the detectors in respect of the paths in the overlap zones; the signals relating to paths near the center of an overlap zone being combined with the signals relating to other paths distributed substantially across the overlap zone but the signals relating to paths near the edges of an overlap zone being combined with the signals relating to only a few, neighboring paths.

Abstract: Computerized tomographic X-ray apparatuses direct X-rays, usually in a fan-shaped distribution, through the body of a patient. In some examples the fan distribution may subtend angles of 50.degree. or more at the source. It has been found that such tubes, particularly of the rotating anode type, tend to have X-ray emission from regions surrounding the focal spot and it is not convenient to use anode shields to eliminate it. This off-focus radiation can present problems, especially when attenuators are used to equalize absorbing paths through the patient, since the off-focus radiation can sometimes be less attenuated than the main beam. It is proposed to correct the signals produced by the X-ray detectors, for off-focus radiation. A profile of off-focus or halo radiation is produced and the attenuation imposed on it is estimated.

Abstract: In a computerised tomographic (CAT) X-ray apparatus passage of the radiation through high absorption (bone) regions can change a characteristic of the radiation, such as its frequency spectrum. This can introduce error into the final representation. Correction is provided by computing a first representation, identifying areas of bone and then determining corrections for those areas which can be used to provide a subsequent move accurate representation. Errors caused by scattering can also be compensated in this way.

Abstract: Computerized tomographic apparatus is described in which a radiation source and an associated detector array execute, concomitantly, reciprocating lateral scanning movements and rotational scanning movements relative to a patient's body, the scanning movements being effected in the plane of a cross-sectional slice of the body which intersects the patient's heart. The patient is located so that the heart is substantially at the center of the scanning movements. The lateral movements are substantially sinusoidal, arranged so that a substantially linear portion of the movement occurs when the source irradiates the heart, and the rotational movement is continuous or substantially continuous and any pauses are only brief, and during alternate lateral scans when the aforementioned substantially linear portions of movement occur. The scanning movements are synchronized to the patient's heart beats so that the heart is irradiated during a quiescent phase of its movement.

Abstract: In a method of examining a body by means of penetrating radiation a source is arranged to provide a fan shaped spread of the radiation and a detector examines the intensity of a plurality of individual beams of radiation defined from the fan. The source and detector are orbited about the body so that the beams are provided at a plurality of angles relative to the body. In the associated processing, the data signals from the detectors are combined so that each combined signal relates to two beams 180.degree. to each other in the orbital movement. A further selection is also made of the data signals so that they are provided to a further processing stage in sets for which each set is of data signals relating to beams which are substantially parallel to each other.

Abstract: A computerized tomographic apparatus is described in which a wide fan of radiation scans a patient by rotating therearound, the fan being substantially flat and being maintained in alignment with a selected cross-sectional slice of a patient's body. Radiation emergent from the body along many substantially linear paths across the slice is detected by a detector means including a vacuum tube device containing a photo-cathode and, spaced therefrom, semiconductive means. Electrons emitted from the photo-cathode in response to light incident thereon (the light emanating from X-ray sensitive scintillating material) are accelerated towards the semiconductive means and impact thereon causing the generation of electrical signals indicative of the amount of X-radiation falling on the scintillating material.

Abstract: A medical diagnostic X-ray machine is described in which X-ray measurements are taken of the attenuation suffered by X-radiation when projected across a cross-sectional slice of a patient's body along each of many substantially linear beam paths and are subjected to compensated back-projective processing to produce an X-ray picture representing the variation of attenuation of the radiation with position over the slice. Neighboring beam paths are arranged to overlap each other.

Abstract: This application describes a rotation-only CT scanner with beam deflections; the deflection and the rotation being so related as to permit the derivation of absorption data in groups focussed on respective "pivot points" outside the detector locus. Data derived from different detectors, but focussed on the same pivot point, relate to groups of paths, some of which overlap, and the overlap is used to compare the performances of different detectors. To reduce data handling, data provided by adjacent detectors can be combined.

Abstract: In a computerized tomographic apparatus for medical radiographic purposes, high definition information is sometimes required in respect of a region inside the body. It is therefore necessary to subject that region to a considerable radiation dosage. This gives rise to difficulties of excessive dosage to the skin and other portions of the body surrounding said region. The invention provides an arrangement whereby radiation is projected through said region by way of different areas of the skin so as to provide the high definition information required for said region without subjecting the skin to excessive radiation dosage.

Abstract: In a computerized tomographic apparatus, different detectors are caused to receive radiation along substantially the same beam path through the body in order to permit the evaluation of differences in performance of the detectors. This evaluation is average with other evaluations made in respect of the same detector for other beam paths so as to reduce the risk that erroneous performance differences may be evaluated in the event that any of the relevant beam paths lies adjacent a bone edge in a patient's body. Also disclosed are techniques for electronically deflecting the radiation so that part at least of the radiation is taken clear of the body and can be detected to provide reference signals.