Abstract: A method and threshold discrimination circuit for threshold discriminating an accumulated charge signal in a charge readout sensor, wherein the accumulated charge signal is shaped with a filter prior to effecting threshold discrimination thereof, and a slew rate of the filter is limited so that the filtered accumulated charge signal reaches a predetermined threshold at a time that remains constant irrespective both of an amplitude of the signal and of charge collection time. Such a threshold discrimination circuit finds particular application in a charge readout sensor in a nuclear imaging system where very accurate determination of the time of photon emission is required.

Abstract: The present invention calculates incidence directions of gamma rays by an incidence direction calculating circuit on the basis of the incidence directions of gamma rays to detectors. And a planar image generating circuit generates planar image data on the basis of count data relating to an event coincident or near-coincident with an incidence direction designated by an operator on an input device.

Abstract: A nuclear medical diagnostic apparatus for detecting gamma rays emitted from the radio isotope (RI) administered to a subject, to generate images showing the functions of the subject, such as metabolism. In the nuclear medical diagnostic apparatus, at least one detector is attached to a rotating ring and located inside the ring. The apparatus can therefore be modified as a one-detector type to a four-detector type. It can easily be graded up from a one-detector type to any one of the other types including the four-detector type. Further, the image-generating mode can be freely changed. Moreover, the apparatus can be small and light.

Abstract: A binder for hydraulic compositions comprises a water-soluble cellulose ether and a long-chain alkylbenzene-sulfonic acid or a neutralization salt thereof. The presence of the long-chain alkylbenzenesulfonic acid compound as a binder component provides hydraulic compositions with a better plasticity at a lower water-soluble cellulose ether content than when the cellulose ether is used alone as the binder.

Abstract: A semiconductor radiation detector has a plurality of semiconductor cells for detecting radiation from a subject. These semiconductor cells include a plurality of voltage application electrodes and a plurality of signal read electrodes. The semiconductor cells are so arrayed that the cell array forms a concave shape and the semiconductor cells are parallel to each other. Since the semiconductor cells are arrayed to form a concave shape, not only semiconductor cells near the center but also semiconductor cells near the peripheries are located close to the subject. This increases the positional resolution and sensitivity. Since the semiconductor cells are arranged parallel to each other, collimated gamma rays always perpendicularly enter the incidence surface regardless of the incident position of the gamma rays. This equalizes the distances the gamma rays travel regardless of the incident positions, so the sensitivity is substantially constant regardless of the incident positions.

Abstract: A semiconductor radiation detector has a plurality of semiconductor cells arrayed in a matrix parallel to the X-Y plane. A plurality of common electrodes for applying an operating voltage to the semiconductor cells are arranged perpendicularly to the X-Y plane. A plurality of signal electrodes for reading out signals from the semiconductor cells are arranged perpendicularly to the X-Y plane. According to a feature of this invention, each common electrode is shared by a pair of semiconductor cells adjacent in the X direction, and each signal electrode is shared by a pair of semiconductor cells adjacent in the X direction. With this arrangement, the dead zone can be reduced to increase the pixel density, in other words, the spatial resolution. If the pixel density is kept unchanged, the sensible zone of the semiconductor cell can be widened to increase the detection sensitivity.

Abstract: A scintillation camera having a detector with a surface and designed to form a tomographic image of a subject from radiation emitted from radio isotope administered to the subject and detected by the detector. The camera comprises a data acquiring device for acquiring data required to reconstruct a tomographic image of the subject, and a detector holder for holding the detector at a predetermined distance from the body surface of the subject while the data acquiring device is acquiring the data. The detector holder includes a sensor located between the subject and the detection surface of the detector, a sensor control circuit for controlling the sensor and detecting ON/OFF state of the sensor, and a detector moving device for moving the detector toward and away from the subject in accordance with the ON/OFF state detected by the sensor control circuit.

Abstract: A gamma camera system of the present invention comprises a main detector for detecting gamma rays emitted from RIs provided to a subject, an emitter for emitting the gamma rays to the subject, and a sub-detector for detecting the gamma rays emitted from the emitter and transmitted through the subject. The sub-detector has at least one semiconductor element for directly detecting the gamma ray having high energy resolution. Based on the output of the sub-detector, an absorption ratio showing to what degree the gamma rays are absorbed in the subject is calculated. The absorption ratios are used to correct the number of the gamma rays counted based on the output of the main detector. Based on the corrected count values, RIs distribution is reconstructed. Thus, since the sub-detector having high energy resolution and the emitter other than the main detector are provided, the absorption ratios having high accuracy can be measured in parallel with imaging.

Abstract: A scintillation camera having a detector with a surface and designed to form a tomographic image of a subject from radiation emitted from radioisotope administered to the subject and detected by the detector. The camera comprises a data acquiring device for acquiring data required to reconstruct a tomographic image of the subject, and a detector holder for holding the detector at a predetermined distance from the body surface of the subject while the data acquiring device is acquiring the data. The detector holder includes a sensor located between the subject and the detection surface of the detector, a sensor control circuit for controlling the sensor and detecting ON/OFF state of the sensor, and a detector moving device for moving the detector toward and away from the subject in accordance with the ON/OFF state detected by the sensor control circuit.

Abstract: A scintillation camera having a detector with a surface and designed to form a tomographic image of a subject from radiation emitted from radio isotope administered to the subject and detected by the detector. The camera comprises a data acquiring device for acquiring data required to reconstruct a tomographic image of the subject, and a detector holder for holding the detector at a predetermined distance from the body surface of the subject while the data acquiring device is acquiring the data. The detector holder includes a sensor, which may for example be an ultrasonic sensor, a pressure sensor, a tension sensor or an optical sensor, located between the subject and the detection surface of the detector, a sensor control circuit for controlling the sensor and detecting ON/OFF state of the sensor, and a detector moving device for moving the detector toward and away from the subject in accordance with the ON/OFF state detected by the sensor control circuit.

Abstract: In a scintillation camera processing a .gamma.-ray emitted from a nuclide administered to a subject, there is provided an element for memorizing a plurality of linearity correction data corresponding individually to a plurality of sub windows dividing a one energy window specified to one energy spectrum distribution of the .gamma.-ray. Further, the camera comprises an element for collecting two-dimensionally the .gamma.-ray, an element for calculating a two-dimensional positional signal and an energy signal of the .gamma.-ray based on information from the collecting element, an element for discriminating strength of the energy signal, an element for selecting one of the plurality of linearity correction data according to a discrimination result of the discriminating element, and an element for correcting the positional signal in linearity using the selected linearity correction data.

Abstract: A radiation detector includes a plate-like monocrystal for converting a radiation ray radiated from an object to be examined to a visible ray, a glass plate provided on the monocrystal for transmitting the visible ray generated in the monocrystal and a plurality of photomultipliers arranged on the glass plate for converting the visible ray inputted through the glass plate from the monocrystal to an electrical signal.

Abstract: In a scintillation camera system, a total number of reference light sources such as LEDs is considerably reduced with reference to a total number of photomultiplier tubes, and a defect occurring in either the reference light source, or the photomultiplier tube can be detected. The scintillation camera system includes: a plurality of photomultiplier tubes (4A:4N) for outputting scintillation signals; at least three reference light sources (5A:5B:5C) positioned continuous to the plurality of photomultiplier tubes (4A:4N), one of these plural photomultiplier tubes (4A:4N) being separated from the three reference light sources at an equidistance; a signal processing unit (6) for processing the scintillation signal outputs from the plural photomultiplier tubes (4A:4N) to produce feedback signals; and a controlling unit (7) for controlling radiation from the reference light sources (5A:5B:5C) in response to the feedback signals.

Abstract: A digital temperture compensation oscillator for digitally compensating a variation in oscillation frequency due to temperatures, by applying a compensation voltage to a voltage controlled oscillator, comprises temperature detection means, A/D conversion means, memory means, operation means and D/A conversion means. The temperature detection means detects temperatures when the voltage controlled oscillator is operated, and generates a temperature signal. The A/D conversion means receives the temperature signal, digitizes the temperature signal, and generates digital temperature data. The memory means stores compensation data corresponding to the compensation voltage as difference data at corresponding addresses. The difference data includes, when N-stage level difference data (N=a positive integer) are utilized, predetermined reference values of 0th difference data to (N-1)-th difference data of the compensation data and all N-th difference data.

Abstract: A digital temperature-compensated oscillator comprises a crystal oscillator, a first memory previously storing digital temperature compensation data obtained by previously measuring the relation between the ambient temperatures and the frequency deviations of the crystal oscillator, a second memory for storing frequency offset amounts of the oscillation frequency of the crystal oscillator, a temperature sensor for outputting analog detection data relating to the ambient temperature, an A/D converter for converting the analog detection data to digital detection data, a readout circuit for reading out temperature compensation data corresponding to the digital detection data and stored in the first memory according to the digital detection data and reading out the frequency offset amount stored in the second memory according to the digital detection data, an operation circuit for effecting the following calculation by use of the readout temperature compensation data and readout frequency offset amount to derive

Abstract: A measurement of standard light is performed during radiation measurement for gain correction and offset correction of radiation measurement apparatus. The standard light emitted by a LED falls on a PMT. An output signal of a preamplifier corresponding to the PMT is entered into a system controller after being subjected to predetermined analog signal processing. The system controller calculates a gain correction value and an offset correction value on the basis of initial correction values and an output value of the preamplifier, whereby gain control and offset control can be performed stably even in radiation measurement.

Abstract: Gamma rays radiated from a radioisotope injected into a subject under examination are detected by a scintillation camera, and position signals indicative of the detected position of the gamma rays and an energy signal are applied to a data-processing unit for imaging the distribution of the radioisotope within the subject. A pulse height analyzer analyzes an energy discrimination signal and provides an imaging control signal when the pulse height of the energy discrimination signal falls within a window of interest. The data-processing unit is responsive to the application of the imaging control signal to thereby image the distribution of radioisotopes within the subject on the basis of the position signals and the energy signal. The energy discrimination signal may have a pileup waveform in which at least two peaks are produced substantially at the same time due to simultaneous detection of gamma rays.

Abstract: A scintillation camera apparatus includes a conversion timing control circuit and a plurality of signal processing channels. The signal processing channels includes a plurality of A/D converters. The A/D conversion periods are not overlapped with each other under the control of the conversion timing control circuit.

Abstract: A scintillation camera apparatus comprises a plurality of photomultipliers, a plurality of high voltage control circuits, and a comparator. The photomultipliers generate radiation energy signals upon receipt of incidence light. The comparator compares the peak pulse heights of the radiation energy signals with the corresponding reference peak values to derive deviation signals. Based upon the deviation signals, the supply of the high voltages to the photomultipliers is independently controlled.

Abstract: A piezoelectric resonator is arranged such that a pair of lead-in conductors extend through a flat hermetically sealed case obtained by bonding a pair of upper and lower halves, and are connected at projecting portions of the conductors to driving electrodes of a piezoelectric element. Electrical connections and mechanical bonding thus are provided by way of the projecting portions.