Abstract: A method and device for stabilizing photomultiplier tubes of a radiation image device against drift by illuminating the photomultiplier tubes with light. A certain number of the photomultiplier tubes are arranged in an array for final application. Then the complete array is illuminated for a certain time period with light having an intensity to produce an average anode current in the photomultiplier tubes which is in the range of 1 to 50 .mu.A.

Abstract: Radiation events of a radiation detector which are subject to deadtime losses during the acquisition time are detected as event triggers. For each detected radiation event a deadtime signal is provided. The acquisition time is subdivided into a succession of evaluation time intervals and the fractional amount of deadtime is measured within each evaluation time interval to obtain a measure for count rate losses. From the fractional amount of deadtime a replication probability is evaluated and dependent thereon all radiation events detected between the end of one evaluation time and the end of a following one are evaluated to generate (a) one pulse for each detected radiation event; and (b) a sequence of a number of pulses for randomly selected events.

Abstract: A proximity detector is provided for a body scanner having a scanning surface. It comprises an energy beam emitting and receiving device in front of the scanning surface of the body scanner for an energy beam projected in a plane parallel to the scanning surface. A signal generator is connected with the energy beam emitting and receiving device for generating a proximity signal when the energy beam becomes weakened or interrupted. The energy beam is preferably a light beam.

Abstract: A counterbalanced radiation detection device comprises a radiation detector having a specific weight. It further comprises means connected with the radiation detector and the base for positioning the radiation detector in different heights with respect to the base and it also includes electronic component means movably mounted on the base for counterbalancing the weight of the radiation detector. Furthermore, means connected with the electronic component means and the radiation detector positioning means are provided for positioning the electronic component means in different heights with respect to the base opposite to the heights of the radiation detector.

Abstract: A method and a circuit are provided for tuning or calibrating the gain of the radiation detectors of a radiation detection system. For each radiation detector tuning point the energy map status is measured in parallel. Thereby an energy response vector is obtained, which is multiplied with a predetermined deconvolution matrix. The deconvolution matrix is the inversion of a contribution matrix containing matrix elements C.sub.ij, each such matrix element C.sub.ij of said contribution matrix representing the relative contribution level of a radiation detector j of said detection system for a point radiation source placed at a location i. Thus a calculated gain vector is obtained with respect to which the gains of the radiation detectors are adjusted such that an ideal gain vector is obtained.

Abstract: A first pinhole and an associated first pin and also a second pinhole and an associated second pin are mounted between a detector head and a detector head supporting structure such that the first pinhole and the first pin are concentric with a first axis and the second pinhole and the second pin are concentric with a second axis. The pins can be shifted relatively to each other along each axis in opposite directions, so that when one pin intrudes in its pinhole the other pin is located outside its pinhole. The axis of the intruding pin defines the trunnion axis of the detector head.

Abstract: A mechanism is provided for mounting a detector head including a collimator onto supporting structure of a radiation detector for rotation about a selected one of a plurality of trunnion axes, the selection being made so that rotation occurs about the trunnion axis which passes nearest to the center of gravity of the head. A first rotatable member is mounted to the supporting structure for rotation about a first trunnion axis and a second rotatable member is mounted to the first rotatable member for rotation about a second trunnion axis. A key mounted on the first rotatable member shifts between protrusion into a first key slot located on the supporting structure and a second key slot located on the second rotatable member. The shifting mechanism is locked when the detector head is in a position other than a collimator changing position.

Abstract: A method and a circuit are provided for processing pulses, caused by a radioactive source and produced by an imaging radiation detector, by applying the technique of weighted acquisition for forming an image. An image weight function is formed corresponding to the source radiation, said function being dependent on the energy of said pulses in consideration of both the energy dependent signal-to-noise ratios of said pulses and the energy dependent modulation transfer functions of said pulses. Thereby a weighting pulse is obtained for each of said pulses, the particular value of said weighting pulse determined by the observed energy of said pulse. Said weighting pulses are then accumulated as said image.

Abstract: A method and device are provided for demounting in a radiation detector a photomultiplier tube the bottom of which is solely bonded with a scintillation crystal assembly by means of an elastic light transparent adhesive. A shearing tool is placed at the bond between photomultiplier tube and scintillation crystal assembly which is operated such that it shears the bond. Especially as a shearing tool a thread is placed around the bond such that it forms a noose. The thread ends have been wrapped around a rod. When twisting the rod the thread continues to wind around the rod thereby making the loop smaller and shearing the bond.

Abstract: A mechanism is provided for mounting a detector head including a collimator onto supporting structure of a radiation detector for rotation about a selected one of a plurality of trunnion axes, the selection being made so that rotation occurs about the trunnion axis which passes nearest to the center of gravity of the head. A first rotatable member is mounted to the supporting structure for rotation about a first trunnion axis and a second rotatable member is mounted to the first rotatable member for rotation about a second trunnion axis. A key mounted on the first rotatable member shifts between protrusion into a first key slot located on supporting structure and a second key slot located on the second rotatable member. The shifting mechanism is locked when the detector head is in a position other than a collimator changing position.

Abstract: From a heart sound signal input the occurrence of a first occurring heart sound is detected. Thereupon a predetermined heart sound enable window time is established, which for a first detection cycle is set to approximately the diastolic interval for the maximum heart rate to be detected. If a second heart sound occurs within this heart sound enable window time, this second heart sound is detected as a systole heart sound. The first heart sound may be detected as a diastole heart sound. If a second heart sound does not occur within the heart sound enable window time the procedure is repeated with increasing heart sound enable time as long as a second heart sound occurs within an increased heart sound enable window time. Cardiac cycle data provided by diagnostic equipment is gated from discriminated heart sound signals and also ECG signals to provide more meaningful diagnostic analysis.

Abstract: From a heart sound signal input the occurrence of a first occurring heart sound is detected. Thereupon a predetermined heart sound enable window time is established, which for a first detection cycle is set to approximately the diastolic interval for the maximum heart rate to be detected. If a second heart sound occurs within this heart sound enable window time, this second heart sound is detected as a systole heart sound. The first heart sound may be detected as a diastole heart sound. If a second heart sound does not occur within the heart sound enable window time the procedure is repeated with increasing heart sound enable time as long as a second heart sound occurs within an increased heart sound enable window time. For monitoring remotely or by a using recording, an ECG signal is modulated and combined with the associated heart sound signal for use as a single combined signal.

Abstract: From a heart sound signal input the occurrence of a first occurring heart sound is detected. Thereupon a predetermined heart sound enable window time is established, which for a first detection cycle is set to approximately the diastolic interval for the maximum heart rate to be detected. If a second heart sound occurs within this heart sound enable window time, this second heart sound is detected as a systole heart sound. The first heart sound may be detected as a diastole heart sound. If a second heart sound does not occur within the heart sound enable window time the procedure is repeated with increasing heart sound enable time as long as a second heart sound occurs within an increased heart sound enable window time. For diagnostics synchronization signals developed exclusively from the heart sound signals are used to validate data from diagnostic equipment such as a gamma camera.

Abstract: Improved method and circuit are disclosed for processing pulses of a pulse train such that tails of pulses ("A" pulses) which precede a valid true pulse ("T" pulse) to be processed and/or pile-up pulses ("P" pulses) which are piled up on the tails of preceding "T" pulses are eliminated. To eliminate the tails of an "A" pulse a first signal is produced at the occurrence of a "T" pulse. This first signal simulates the tail of the "A" pulse and it is subtracted from the tail piled up "T" pulse. To eliminate a "P" pulse a second signal is produced, when a "P" pulse piled up on the "T" pulse occurs. This second signal simulates the tail of the "T" pulse which tail is cut off at the occurrence of a "P" pulse. This simulated tail is then processed instead of the true tail of the "T" pulse.

Abstract: The radiation detecting apparatus contains at least one photomultiplier tube for the detection of light. It has been found that the photomultiplier tube will emit erroneous output signals when exposed to a perturbing magnetic field. This is particularly true for photomultiplier tubes used in scintillation cameras and in emission computed tomography systems where the detector head containing photomultipliers changes position during operation. In order to reduce the magnetic field sensitivity, the radiation detection apparatus contains means for superimposing an artificial magnetic field on the perturbing magnetic field at the location of the photomultiplier tube. This artificial field may either be a compensating field or, preferably, an enhancing field which is larger than the perturbing field. The artificial field may be either generated by coils, such as Helmholtz coils, or by a permanent magnet. The coil(s) may be arranged inside or outside the camera head.

Abstract: The radioactive structure comprises a radioactive source surrounded by a housing. The housing contains a first and second shielding body and a connecting device. The first shielding body has a protrusion which contains a first recess for receiving the radioactive source. The second shielding body has a second recess in one face end which accommodates the protrusion and a conical aperture communicating with the second recess in another face end. The connecting device connects the first shielding body to the second shielding body. When the radioactive source is inserted into the first recess and when the protrusion is located in the second recess, the radioactive source emits radiation primarily through the conical aperture into the environment. The source preferably contains americium which emits gamma radiation. The structure may be used as a motion correction sensor or as a marker in nuclear diagnostic imaging.

Abstract: Improved detection circuitry is disclosed for calculating the position on the crystal of a scintillation event in a scintillation camera. Electrical signals developed by photomultiplier tubes for successive events are weighted by a resistor matrix and transferred to integrators which develop event position signals based on the quanta of radiation incident on the scintillation crystal. To improve the count rate without sacrificing the resolution, parallel integrators are provided so that a second integrator can integrate electrical signals from a second scintillation event during the time that a first integrator is processing the signals from a first scintillation event. Common storage buffers are connected to the integrators to hold the integrated signals for further processing.

Abstract: An attenuation zone plate for coded-aperture imaging of a radiation source has mercury contained within a wedge-shaped chamber in a plastic housing. Reservoir and relief cavities facilitate filling the housing with mercury and accommodate changes in mercury volume. Lead plates positioned on the perimeter of the housing provide a field of view mask. In one embodiment, the housing cover pivots to vary the wedge angle. Advantages include greater facility in precision manufacturing and greater attenuation pattern flexibility.

Abstract: An improved threshold preamplifier circuit is disclosed for use with the event X, Y position detection circuitry of a scintillation camera. Threshold amplifiers, having a common threshold voltage that is set as a function of the energy of the incident scintillation event, control the respective preamplified photomultiplier tube output signals so that signals from tubes close to the event receive greater weight in the X, Y position analysis than signals from distant tubes. In a preferred embodiment, the threshold voltage is determined by the output of a summing amplifier which sums an unthresholded energy signal Z.sub.nt which represents the total energy of the incident event, an integrated energy signal Z.sub.u which represents the integrated value of the unthresholded energy signal Z.sub.nt, and a constant voltage which represents the preselected zero energy level threshold biasing voltage. Variable resistors control the relative contributions to the summing amplifier input of the Z.sub.nt and Z.sub.

Abstract: An X-ray detector receives X-ray radiation from an object under examination and generates a detector image thereof. An image intensifier including a screen enhances the detector image and generates an image intensifier image which emits light. A video camera views the image intensifier image and generates a video signal comprised of frames of digital data. These data describe the signal levels of the image intensifier image. A display device connected to the camera receives the video signal and displays an image in accordance with the distribution of X-ray radiation. An iris is arranged between the image intensifier and the video camera. The iris has an aperture of variable size for controlling the intensity of light transmitted from the image intensifier to the video camera. A control circuit is provided for controlling the aperture of the iris.