Abstract: An electronic multi-imaging system displays medical images obtained from scans of a patient, and stored in a digital memory, on the screen of a TV monitor. The medical images occupy different spatial locations on the screen and do not overlap. An optical system operatively associated with the screen focuses an image of the screen onto a sheet of photosensitive material such that each of the medical images occupies only a portion of the sheet at predetermined spatial locations that are functionally related to the predetermined spatial locations of the medical images on the screen of the TV monitor.

Abstract: An X-ray tube with an adjustable focal spot is provided wherein the focal-spot position can be moved along the anode and the focal-spot width can be changed by applying a small voltage to the cathode-bias cup. The cathode includes means integral with the cathode for deflecting the flow of electrons to selectable focal-spot areas on the anode in response to an external drive circuit. The cathode includes a filament for emitting electrons to impinge on the anode, and a cathode cup having first and second parts electrically insulated from each other. The filament is electrically insulated from at least one of the parts of the cathode cup. The electrical insulation between the first and second parts of the cathode cup can be provided by a gap therebetween. The device includes biasing means for applying a voltage between the filament and the cathode to control the size and position of the region of impingement of the electron beam on the anode. The anode can be rotatable with respect to the cathode.

Abstract: A method for the correction of ring artifacts in images obtained by rotate-rotate computerized tomography (CT) scanners includes the step of reconstructing an original image, which comprises a real image and a ring artifact image. The ring artifact image is determined by edge enhancing the original image and dividing the edge enhanced original image into rings or annuli with the annuli being concentric around the axis of rotation. The average intensity is determined for each concentric annulus. This average value of each annulus is substracted from pixels of the original image belonging to that annulus to provide a ring artifact free image.

Abstract: Systems and methods are presented for reprojecting images which comprise taking the two-dimensional Fourier transform of the image, interpolating the transform in order to obtain the values on radial lines, and taking the inverse one-dimensional Fourier transforms of the radial lines.

Abstract: A set of two-dimensional views of a body are provided from successive azimuthal angles with respect to a given axis. The set of views of the body are successively displayed on a display screen which shows the body as rotating about an axis. A point of interest in the body also appears to rotate about the axis. That view at which the point of interest is maximally displaced from the apparent axis of rotation is used to determine the angular position of the point of interest. The true displacement of the point of interest from the axis of rotation and its true displacement along the axis of rotation are available from that view. Thus, the cylindrical coordinates of the point of interest are known. To check the accuracy with which the coordinates of the point of interest have been determined, a cursor is established in the stopped view, and the projection of the cursor in the other views is calculated in a conventional manner.

Abstract: A system is provided for transferring a series of images which are displayed successively on a screen of a video monitor using optical means, onto a photosensitive surface by juxtaposing successive elemental images to form a unique composite image. The composite image is directly created on the screen of the video monitor without the necessity of translationally displacing the various elements relative to one another to achieve the framing or to vary the magnification ratio. The composite image is created by successively sweeping various portions of the screen of a high-definition tube. The amplitude and the centering of the sweep signals are determined, as a function of the selected format, by converters run by programmable memories.

Abstract: A method and apparatus for high-speed ultrasonic imaging of very rapidly moving bodily structures. A transducer produces sequential data frames corresponding to sequential images of bodily cross-sections produced by periodically scanning a body with an ultrasound beam produced by the transducer. Reflected ultrasonic echo pulses are digitized and stored in a memory array in which each data frame is stored in a single segment of a plurality of memory segments which form the memory. The transducer periodically scans the body at a predetermined first rate, whereas the sequential display of the sequential data frames occurs at a second predetermined rate which is different from the first rate. The system permits acquisition of data at a rate which is greater than the perception rate of the human eye and display of the acquired data at a rate which can be visualized by a human observer.

Abstract: Equipment and methods are presented for rearranging divergent beam derived data into parallel data to enable decreasing the number of preprocessing computations and improving the quality of the resulting tomograph. The equipment and method comprise means and steps which vary the spacing of at least portions of the resulting parallel projections, so that when the parallel projections with varied spacings are combined with the parallel projections that have not had their spacing varied, the cupping artifacts normally present when using projections obtained from rearranging are cancelled.

Abstract: A plasma electron source has an apertured cathode, and a housing for defining a cavity behind the aperture. A trigger electrode, in communication with the cavity, is responsive to a short-duration trigger pulse for establishing plasma in the cavity. The plasma is sustained in the cavity subsequent to the termination of the trigger pulse by a bias circuit, which biases the cavity at a relatively low voltage with respect to the cathode for a period of time much longer than the duration of the trigger pulse.

Abstract: A sector-scan ultrasonic imaging apparatus includes a biopsy attachment mounted on the housing of the imaging apparatus for positioning a biopsy needle relative to the ultrasonic scan head of the imaging apparatus. An image display device displays both an image of the region scanned by the scan head and a predetermined, superimposed electronic representation of the position of the biopsy needle-line relative to the probe scan head. The biopsy needle-line is calibrated with a scan head coordinate system which defines a sector sweep of the scan head by determining the coordinates of the needle-line in the scan head coordinate system independently of determining the particular spatial relationship of the needle-line in operative position relative to the scan head. A calibration member adapted to be mounted on the biopsy attachment includes at least two ultrasonic reflection regions which are scanned by the scan head during the calibration mode and displayed on an image display device.

Abstract: A gamma camera comprises a scintillation crystal having an index of refraction of 1.80-190, a collimator for imaging the object on one face of the scintillation crystal, an array of photodetectors arranged around the opposite face of the scintillation crystal, and a light guide interposed between the opposite face of the scintillation crystal and the plurality of photodetectors. The light guide is selected to have an index of refraction of at least 1.60, higher than in the conventional gamma camera, whereupon it has been found that the detection efficiency and the positional accuracy of each scintillation event can be increased, to thereby increase the sensitivity and the spatial resolution of the gamma camera.

Abstract: An image-reconstructive technique for examining a body by means of penetrating radiation, such as X-rays, is described in which a pre-body collimator having a two-dimensional array of radiation-transmitting holes each bordered by radiation non-transmitting walls is disposed between the body and the source of radiation, and a plurality of exposures are made onto a radiation-sensitive surface, in which the radiation is projected through the collimator while the radiation source is at a plurality of different locations, such that during the successive exposures, the radiation from the source passes through different ray paths defined by the holes in the pre-body collimator. The radiation level received by each of the radiation-sensitive surface elements is detected, stored, and processed to reconstruct the two-dimensional radiation pattern but with enhanced resolution. Preferably a post-body collimator is also used to suppress scattering. Described are a four-exposure procedure and a nine-exposure procedure.

Abstract: The intensity distribution of a radiation field imaged on a scintillation crystal of a gamma camera can be quantified by assigning to each elemental area of the crystal, a number representing the number of light events calculated to have occurred in the given elemental area within a predetermined period of time. The resolution of the camera is improved by weighting the contents of the elements in the memory in accordance with the probability that an event, calculated to have occurred in a given elemental area, actually occurred therein, such that the weighted contents of the memory more closely approaches the actual density distribution of light events as compared to the unweighted contents of the memory.