Patents Assigned to EMI Limited
  • Radiography
    Patent number: 4153839
    Abstract: The specification discloses a scintillator crystal configuration which enables a group of crystals to be closely packed together, for example in a V-formation. Each crystal receives x-radiation through an input face, which is of small area, and emits light through an output face, to which a photodiode is preferably attached and which is therefore of larger area than the input face. Also disclosed is a medical radiographic apparatus incorporating an X-ray detector unit containing a number of such crystals.
    Type: Grant
    Filed: August 11, 1977
    Date of Patent: May 8, 1979
    Assignee: EMI Limited
    Inventors: Godfrey N. Hounsfield, Tai Y. Chan
  • Radiography
    Patent number: 4150294
    Abstract: In a computerized tomographic apparatus, a scanning device is used to project radiation through a slice disposed cross-sectionally of a body along many sets of pencil-like beam paths. Each set of paths is characterized by being oriented at a respective angle, or in some circumstances a respective mean angle, in the slice. The absorption suffered by the radiation on traversing each beam path is measured and, from all the values of absorption, the coefficient of absorption of the radiation at each of many locations distributed over the slice is calculated. The invention extends the number of paths in some only of the aforementioned sets to include further paths traversing a zone outside the slice and the absorption values relating to these further paths are used to improve the accuracy of the calculation of the coefficients of absorption.
    Type: Grant
    Filed: October 26, 1976
    Date of Patent: April 17, 1979
    Assignee: EMI Limited
    Inventor: Godfrey N. Hounsfield
  • Radiography
    Patent number: 4139775
    Abstract: A mechanical arrangement for use in computerized tomographic apparatus so as to permit the examination of volumetric body slices and body slices tilted with respect to the examination axis is described. The radiation source is mounted on an inner tilt frame which can rotate, by way of a lockable bearing, in an outer tilt frame which can be tilted relative to a sub frame which can be locked or free relative to the main frame of the apparatus. The outer tilt frame can also rotate, relative to the main frame, in a lockable bearing.
    Type: Grant
    Filed: July 18, 1977
    Date of Patent: February 13, 1979
    Assignee: EMI Limited
    Inventor: Anthony M. Williams
  • Measuring arrangements for electrical currents
    Patent number: 4138640
    Abstract: An arrangement for measuring electrical currents is described, having advantageous application to the measurement of the small currents obtained from photodiodes associated with radiation sensitive detectors in a computerized axial tomographic apparatus. The arrangement involves a technique which, in effect, performs a least squares analysis on variation of the current from a detector over each of a succession of predetermined time intervals.
    Type: Grant
    Filed: April 30, 1976
    Date of Patent: February 6, 1979
    Assignee: EMI Limited
    Inventor: Charles P. Cousins
  • Fan beam CT apparatus with post-processing weighting of picture element signals
    Patent number: 4138611
    Abstract: In a computerized tomographic apparatus in which a wide angled, fan-shaped distribution of radiation is rotated around a body to be radiographed and detectors are provided to produce electrical output signals indicative of radiation emergent from the body along many beam paths, the signals can be sorted into sets relating to parallel sets of beam paths distributed across a cross-sectional slice of the body. However, the beam paths to which the signals so sorted relate are non-uniformly spaced beam paths, and the invention provides means whereby a processing technique known as convolution, which is of proven usefulness in computerized tomography but which, for best accuracy, operates upon output signals relating to sets of uniformly spaced, parallel beam paths, can be applied to the signals as sorted and a post-processing error compensation is effected to restore accuracy.
    Type: Grant
    Filed: May 3, 1977
    Date of Patent: February 6, 1979
    Assignee: EMI Limited
    Inventor: Godfrey N. Hounsfield
  • Ultrasonic apparatus
    Patent number: 4137775
    Abstract: In an ultrasonic investigating apparatus a transducer can receive reflections from points in the body for which the position in one direction is relatively well known as a result of accurate range gating but for which the position in another direction is relatively less known in view of the relatively wide ultrasound beams used. Thus the reflections are only known as originating from lines in the body. These line integrals of reflection of ultrasonic energy are processed by methods appropriate to line integrals in general, as known for line integrals of X-ray absorption for example, to more accurately position the reflecting points in the body. A propagation velocity distribution can also be determined for the body to further improve the accuracy.
    Type: Grant
    Filed: September 27, 1976
    Date of Patent: February 6, 1979
    Assignee: Emi Limited
    Inventor: Christopher A. G. LeMay
  • Medical radiographic apparatus with means for notating detector ring
    Patent number: 4137455
    Abstract: In a computer-assisted tomography (CAT) apparatus, in which a fan-shaped X-ray distribution is rotated about the patients body, it is possible to use a ring of stationary detectors disposed to receive the radiation after passage through the body. In this arrangement the ring of detectors is of smaller radius than the locus of motion of the radiation source. It would appear that this would cause the detectors to obscure the body from the radiation. An arrangement disclosed moves out of the radiation beam those detectors which would present an obstruction so that only those required to collect radiation lie in the beam.
    Type: Grant
    Filed: June 29, 1977
    Date of Patent: January 30, 1979
    Assignee: EMI Limited
    Inventor: Richard W. Fetter
  • Optical pointer for radiographic apparatus
    Patent number: 4132900
    Abstract: A therapeutic radiographic apparatus includes a source of a pencil-like beam of penetrating radiation which requires to be positioned relative to a patient's body so that the radiation passes, at all times during therapy, through an anomaly, such as a tumor, in the patient's body. It is difficult to maintain coincidence of the beam with the anomaly, and this invention provides means for indicating optically a point of contact of the beam with the patient's body. The point of contact may, for example, be the point of emergence of the beam from the body.
    Type: Grant
    Filed: May 12, 1977
    Date of Patent: January 2, 1979
    Assignee: EMI Limited
    Inventors: William E. Smith, Robert J. Rorden
  • Radiography
    Patent number: 4132895
    Abstract: In a computerized tomographic CT scanner, a lateral scan of a pencil beam of radiation is effected by causing an apertured, annular collar to rotate around a source of a fan-shaped spread of radiation. The motion of the collimator causes a pencil like beam to sweep angularly across the body. Successive sweeps, caused by successive apertures, are in the same direction.
    Type: Grant
    Filed: July 27, 1977
    Date of Patent: January 2, 1979
    Assignee: EMI Limited
    Inventor: Robert J. Froggatt
  • Radiography
    Patent number: 4126786
    Abstract: In a computerized tomographic system in which a fan of radiation effects a rotational scan and the detectors are fixed, collimation is achieved by means of plates hinged adjacent the detectors. The plates are moved by means of a ring, the center of which is caused to execute a circular motion about the center of rotation of the system. The ring carries projections which engage with the ends of the plates remote from the detectors.
    Type: Grant
    Filed: June 20, 1977
    Date of Patent: November 21, 1978
    Assignee: EMI Limited
    Inventors: Christopher Archibald G. LeMay, Alan G. Blay
  • Radiography
    Patent number: 4126785
    Abstract: In a computerized tomographic apparatus which involves both rotational and translational scanning movements of the source relative to the body, the translational movements are timed so that the radiation passes through, or adjacent, a mobile organ (such as the heart) of the body while that organ assumes a predetermined position, or range of positions, in its movement.
    Type: Grant
    Filed: May 12, 1977
    Date of Patent: November 21, 1978
    Assignee: EMI Limited
    Inventor: Godfrey N. Hounsfield
  • Radiography
    Patent number: 4126787
    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.
    Type: Grant
    Filed: December 15, 1977
    Date of Patent: November 21, 1978
    Assignee: EMI Limited
    Inventor: Godfrey N. Hounsfield
  • X-ray tubes
    Patent number: 4126805
    Abstract: An X-ray tube is described in which, in order to produce a well defined electron beam which can be accurately focussed on the target of the tube, the cathode comprises a flat plate member, such as a tape or foil, the surface finish of which is sufficiently smooth that electrons are emitted therefrom with lateral energies below 0.2 electron volts. The aforementioned surface finish is such that irregularities in the electron-emitting surface of the cathode do not exceed one micron in amplitude.
    Type: Grant
    Filed: October 12, 1976
    Date of Patent: November 21, 1978
    Assignee: EMI Limited
    Inventor: Robert P. Randall
  • Video display arrangements
    Patent number: 4125858
    Abstract: For a computerized radiographic apparatus, providing a cross-sectional representation of absorption of radiation in the body of a patient, there is provided a television standard display of cross-section. The display can be high-definition monochrome or in color. An arrangement is provided in which the high definition monochrome is displayed with low saturation color-wash superimposed thereon to highlight significant features in the monochrome picture.
    Type: Grant
    Filed: March 25, 1977
    Date of Patent: November 14, 1978
    Assignee: EMI Limited
    Inventors: Godfrey N. Hounsfield, Donald F. McLean
  • Radiography
    Patent number: 4123659
    Abstract: In a radiographic apparatus in which a scanning X-ray tube is used it is desirable to properly relate the scanning of the X-ray origin with other scanning motions of the apparatus. In this arrangement a scan progress detector is inserted partly into the radiation to detect its scan motion. In one eXample it is a collimator block to provide a sinusoidal output as the scan progresses. Pulses derived from the sinusoid are compared with signals representing an ideal scan and the differences between them used to correct the source scan control.
    Type: Grant
    Filed: May 23, 1977
    Date of Patent: October 31, 1978
    Assignee: EMI Limited
    Inventor: Colin C. Oliver
  • Radiographic apparatus
    Patent number: 4118631
    Abstract: In therapeutic radiographic apparatus it is desirable to maintain the penetrating radiation in passing through tissue to be irradiated, rather than surrounding healthy tissue, despite movements of the patient. A shadowgraph radiographic picture of part of the patient is obtained by derivation from cross-sectional radiographic pictures from computerized axial tomography (CAT) apparatus. A similar shadowgraph picture is obtained, during therapy treatment, by collecting the therapy radiation after passing through the body. The two pictures are compared to determine the position of the therapy radiation relative to the tissue to be irradiated and the position is adjusted in response to the comparison.
    Type: Grant
    Filed: March 25, 1977
    Date of Patent: October 3, 1978
    Assignee: EMI Limited
    Inventor: Robert Justin Froggatt
  • Radiographic apparatus with correction for radiation hardness variations
    Patent number: 4118628
    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.
    Type: Grant
    Filed: May 3, 1977
    Date of Patent: October 3, 1978
    Assignee: EMI Limited
    Inventor: Godfrey Newbold Hounsfield
  • Radiology
    Patent number: 4118629
    Abstract: Computerized tomographic apparatus is capable of producing representations which show, with high accuracy, the absorption coefficients, with respect to x-radiation, at various locations distributed over one or more selected cross-sectional slices of a patient's body. The evaluation of the absorption coefficients is effected by determining the absorption suffered by the radiation on traversing each of many substantially linear paths from a source of the radiation to a detector means, the paths traversing the body slice. The invention resides in compensating for changes in the energy spectrum of the radiation as projected through the body along different ones of said paths, which changes could otherwise impair the accuracy of said representations.
    Type: Grant
    Filed: March 11, 1977
    Date of Patent: October 3, 1978
    Assignee: EMI Limited
    Inventor: Godfrey Newbold Hounsfield
  • Computerized radiography with means to process only selected signals
    Patent number: 4117336
    Abstract: In order to obtain rapidly a representation of the results of a computerized tomographic examination of a patient, some of the data obtained during the examination is ignored. The representation is thus produced rapidly, as desired, but on the basis of less information than is actually available. A representation using all the available information can be produced later, as required.
    Type: Grant
    Filed: April 6, 1977
    Date of Patent: September 26, 1978
    Assignee: EMI Limited
    Inventor: Stephen Ronald Bates
  • Radiography
    Patent number: RE29894
    Abstract: Radiographic apparatus is described in which a thin planar slice of the body is examined by a swath of penetrating radiation such as X-rays. Collimators are provided for collimating the radiation after it has passed through the body into a set of beams which are directed into respective detectors. The swath of radiation, the collimeters and the detectors are orbited in the plane of the slice so that the beams pass through the body from many different angular directions. Means are provided for additionally displacing at least the collimators relative to the source so that the relative position of the beams and gaps between the beams are changed during the orbital movement.
    Type: Grant
    Filed: February 28, 1977
    Date of Patent: January 30, 1979
    Assignee: EMI Limited
    Inventor: Godfrey N. Hounsfield