Abstract: The current amplifier with automatic drift correction is designed for use in conjunction with computerized tomographic scanners or other apparatus. The amplifier comprises a differential amplifier with a first input connected to a photodiode or other source of current to be amplified. An integrating amplifier is connected between the differential amplifier output and a second differential amplifier input. The integrating amplifier has a time constant which is long compared with the period during which the diode current is to be amplified to provide automatic drift correction. A feedback loop connects the output of the differential amplifier with the first differential amplifier input. The feedback loop comprises a pair of matched transistors interconnected to form a current mirror. A first resistor connects the current mirror with ground. Current flow through these two resistors is summed to form the current flow received by the current mirror.

Abstract: In a rotating fan beam tomographic scanner there is included an adjustable collimator and shutter assembly. The assembly includes a fan angle collimation cylinder having a plurality of different length slots through which the beam may pass for adjusting the fan angle of the beam. It also includes a beam thickness cylinder having a plurality of slots of different widths for adjusting the thickness of the beam. Further, some of the slots have filter materials mounted therein so that the operator may select from a plurality of filters. Also disclosed is a servo motor system which allows the operator to select the desired fan angle, beam thickness and filter from a remote location. An additional feature is a failsafe shutter assembly which includes a spring biased shutter cylinder mounted in the collimation cylinders. The servo motor control circuit checks several system conditions before the shutter is rendered openable. Further, the circuit cuts off the radiation if the shutter fails to open or close properly.

Abstract: The method of determining collimator aperture efficiency for a computerized tomographic scanner having a plurality of radiation detectors positioned along a detector arc, a source of radiation having a focal spot having radiation flux distribution positioned across a scan circle from at least part of the detector arc, and a collimator having a plurality of apertures arranged in a collimator arc around said source.Also disclosed is a tomographic scanner having a circular detector arc, a radiation source moveable along a circular arc and an arcuate collimator having apertures in which the width of the collimator aperture in the geometry of the system has high efficiency. The ratio of the detector radius to the source radius, to the collimator radius, to the aperture width is 36:24.3;9.4:0.024.

Abstract: A tomographic scanner for subjecting a planar region of a patient to radiation and producing an image representing the planar region in which at least the source or beam of radiation is moved with a varying speed. In particular, in a traverse and rotate type scanner, a carriage carrying the radiation source and detector(s) is traversed relative to the patient with generally simple harmonic motion. Additionally, vibration is reduced by using a motor, which may include a flywheel, running at substantially constant speed to traverse the carriage. Vibration is further reduced by connecting the motor for rotating the carriage to the carriage through a flexible, e.g. chain, drive. Cable connections to the X-ray tube and other elements carried by the moveable carriage are simplified with a bicycle-chain like flexible cable support.

Abstract: The video speed logarithmic analog-to-digital converter includes a plurality of parallel paths. In a first path, a plurality of comparators compare an analog input signal with a plurality of logarithmically incremented first reference signals. The number of first reference signals which fail to exceed the analog input signal is converted into a binary representation of the most significant bits of the logarithm of the analog input signal. A second parallel path determines the least significant bits by producing a logarithmically attenuated analog input signal and comparing the attenuated analog input signal with a plurality of logarithmically incremented second reference signals. The number of second reference signals which fail to exceed the attenuated analog input signal is converted into a binary representation of the least significant bits of the logarithm of the analog input signal.

Abstract: The invention relates to a video display device which includes a memory for storing intensity values for each pixel of the video display. Connected with the memory is a persister which decreases the intensity values as a selectable function of time such that a displayed image will appear to fade. Also connected with the memory is an input for increasing specific intensity values in response to the receipt of input data corresponding to that specific display pixel. The invention further relates to a scintillation camera in combination with the video display device in which input data indicates the occurrence of a radiation caused scintillation at some corresponding coordinate position and in which the rate of image fading is consonant with the rate of data acquisition, whereby a real-time display of the passage of a radioisotope through a patient may be produced.

Abstract: A CT scanner has an outer circular array of stationary radiation detectors for an inner concentrically revolving source of radiation emitted in a fan pattern subtending a number of the detectors. A number of analog signal processing channels equal to the maximum number of subtended detectors at any given time is automatically connected via switching circuitry to receive the outputs of only the detectors within the fan pattern.

Abstract: A radiation detector suitable for use in tomographic scanners comprising at least one cadmium tungstate scintillation crystal optically coupled with a silicon photodiode or other photoelectric transducers. A plurality of cadmium tungstate crystals may be coupled to one silicon photodiode with fiber optic light guides. In a tomographic scanner, radiation passing through the scan circle impinges on the cadmium tungstate crystals causing them to scintillate. The light scintillated strikes the area of the p-n junction of the photodiode causing the photoelectric effect to be manifested. The intensity of radiation striking the crystal is determined by measuring the photoconductive conductance, photoemissive current or photovoltaic potential. From these intensities an image is computed of the radiation attenuation in the examined scan circle.

Abstract: The intrinsic nonuniformity of a radioisotope camera having an array of photomultiplier tubes viewing a scintillator crystal assembly is improved by comparing an internally generated correction factor from 1 to n, assigned to a location where a radiation event has been detected, to a random number between 1 and n and then discarding the radiation event datum if the correction factor is less than the random number. Correction factors are first generated by comparing the count at each location with an average minimum count in the presence of a uniform flood source.

Abstract: A control and take-up mechanism for controlling and protecting at least one elongated cable and the like which may be employed to supply operating power, fluids, controls and so on to an operating member mounted within an apparatus and wherein the operating member is selectively movable within the apparatus through an operating plane between a first position and a second position spaced therefrom. The take-up mechanism is comprised of an arcuate cable trough fixedly mounted to the apparatus in a plane parallel to the operating plane with a portion of the elongated cable leading to the operating member longitudinally disposed therein. A cable wheel assembly is received in the trough in rolling engagement therewith and includes a hub and opposed sides which define a cable channel therebetween.

Abstract: An automatic variable collimator which controls the width and thickness of X-ray beams in X-ray diagnostic medical equipment, and which is particularly adapted for use with computerized axial tomographic scanners. A two-part collimator is provided which shapes an X-ray beam both prior to its entering an object subject to radiographic analysis and after the attenuated beam has passed through the object. Interposed between a source of radiation and the object subject to radiographic analysis is a first or source collimator. The source collimator causes the X-ray beam emitted by the source of radiation to be split into a plurality of generally rectangular shaped beams. Disposed within the source collimator is a movable aperture plate which may be used to selectively vary the thickness of the plurality of generally rectangular shaped beams transmitted through the source collimator.

Abstract: A versatile patient table system for transverse axial scanners employs front and rear tables with a spanning patient pallet for abdominal scans. A motorized conveyer belt on the front table increments the axial position of the patient. For brain scans the rear table and patient pallet are replaced by a head restraint assembly with a hinged headrest, check pad restraint members and a body pad which rests on the conveyer belt on the front table. In the automatic mode of operation, the belt moves either the body pad or the patient pallet out from the scanner in controlled increments triggered by the image processor. The hinged metal seam of the belt is used for indexing the extreme outward and inward positions.

Abstract: Rotary safety shutter mechanisms for use in computerized tomographic X-ray scanners of the type wherein a source of radiation and a detector means are mounted for movement on opposite sides of a medium in order that the radiation passes through successive planar sections of medium and is attenuated and detected to give an output. The safety shutter mechanisms are arranged to be positioned adjacent the outlet aperture of the radiation source to selectively block the outlet upon occurrence of a predetermined condition. Two different embodiments of safety shutter mechanisms are disclosed. In each embodiment, the mechanism comprises a housing mounted adjacent the outlet aperture and having a through passage through which radiation from the source can pass. A cylindrical shutter member is carried in the housing transversely of the passage and mounted for rotary movement between a first position which permits the flow of radiation from the source and a second position which blocks the flow.

Abstract: The process of this invention includes detecting gamma radiation with a radiation sensing device, converting the gamma radiation to light radiation, viewing the light radiation with photomultiplier tubes and giving electrical impulses in response thereto. The impulses are operated on to correct for any distortion and to give an indication of the relation to location of the radiation. An area of interest, for the purpose of scanning, is selected and electronically masked. During a first pass, initial scanning is done electronically without physical movement of the radiation sensing device head. After initial electronic scanning, a detector head passes over the radiation of interest while sensing radiation. At the end of the mechanical movement, an area of radiation is again electronically scanned. A cot supporting the section of radiation is moved transverse to the longitudinal movement of the head after the first pass. A scan in the opposite direction occurs similar to that in the first direction.

Abstract: A radiation sensing device including a collimator, a disc-shaped scintillation crystal in close proximity thereto; at least three substantially parallel photomultiplier tubes adjacent to one side of the scintillator and circuitry for locating a scintillation in the crystal. In particular, the circuitry includes a diode bias to correct for distortion and non-uniformity which results from placing the photomultiplier tubes adjacent to the scintillator.