Siemens Gammasonics, Inc.

Everett W Stoub

Dennis E Persyk

Gerd Muehllehner

Raymond P DeVito

Anthony P Del Medico

James G Colsher

Upon the detection of a scintillation event at an event pixel, a plurality of associated pixels are identified. Weights are assigned to the event pixel and to all of the associated pixels in such a manner as to attribute the event over an area in a statistically accurate manner. A current sum of all weights which have been previously assigned to each pixel is stored. Unblank signals are generated, based upon this current sum, and the current sum is updated to account for the number of unblank signals so generated.

Multiple pixel area-weighted acquisition system for scintillation cameras

A thick layer of CsI(Na) is heated to or slightly below its melting point. The CsI(Na) is held at that temperature for 7 to 10 hours and is cooled to room temperature, preferably in two steps. The resulting scintillation crystal is translucent or transparent.

Scintillation crystal and method of making it

A scintillation crystal is provided for a radiation detector, which comprises a first layer of a crystal material having relatively poor mechanical properties, however having a high energy resolution; and a second layer of a crystal material having relatively good mechanical and optical properties. Both layers are arranged in sandwich form.

Scintillation crystal for a radiation detector

A radiation detector circuit, which comprises a radiation detector containing a scintillation crystal and a photomultiplier tube for real time photon measurement having a pulse output, and which also includes a plurality of pulse counters each having a pulse input and a count signal output. Between the pulse output of the photomultiplier tube and the pulse inputs of the pulse counters a time multiplexer is provided for connecting each pulse input of each counter in succeeding time periods with the pulse output of the photomultiplier tube. Furthermore, an evaluation circuit is connected with the count signal outputs of the counters for evaluating each count signal of each counter measured during each of said succeeding time periods in the sense of error estimates and trend analysis.

Radiation detector circuit with real time photon counting

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.

Method and circuit for correcting count rate losses of radiation events

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.

Proximity detector for a body scanner

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.

Method and circuit for stabilizing conversion gain of radiation

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.

Method and circuit for processing pulses by applying the technique of

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.

Method and device for demounting in a radiation detector a

A method and apparatus for correcting for the spatial distortions of scintillation cameras or similar image forming apparatus. The spatial distortion correction method accurately and precisely determines distortion correction factors in an off-line test measurement and analysis phase prior to actual on-line diagnostic use. The distortion correction factors are initially determined from image event data that is obtained during the test measurement phase by orthogonal line pattern images. Data from a uniform field flood image is also utilized during the test measurement phase to refine and modify the distortion correction factors utilizing the gradient of a function of the field flood image data. Scintillation camera image repositioning apparatus is provided and includes a memory having the correction factors stored therein in a predetermined array. During the on-line use of the scintillation camera and associated image display system, the image repositioning apparatus transforms the data from the scintillation camera in accordance with the stored distortion correction factors. In a preferred arrangement, the image event data is repositioned or corrected event by event.

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Villa Park, IL, United States of America

Everett W Stoub