Park Medical Systems Inc.

Independent Scintillation Imaging Systems (isis) Inc.

Independent Scintillation Imaging Systems, Inc.

Abel Ferreira

Iain Stark

James Anglehart

Miljenko Lucic

Vuk Bartulovic

For accurate position calculation of scintillation events in a gamma camera, photodetector signals are processed based on small groups of photodetectors surrounding the scintillations. Relative position correction and energy correction is carried out based on rough position values relative to the group of photodetectors, taking into consideration the number of the center photodetector and the sum of all photodetector signals in the group.

Position calculation and energy correction in the digital scintillation

For accurate position calculation of scintillation events in a gamma camera, improved methods are disclosed calibrating gain of photodetectors. The camera system may comprise an array of LEDs optically coupled to a scintillator crystal in which signals from photodetectors also coupled to the crystal are separated into those resulting from test LED pulses and actual gamma ray induced scintillations. The LED induced signals may be used for camera calibration while the camera is in image collecting mode. Image clarity may also be improved by correcting roughly calculated positions as a function of the roughly calculated positions, and by eliminating events which do not exactly correspond to nuclear decay emissions as a function of the events' positions.

Position calculation in a scintillation camera

A scintillation data collecting apparatus and method are provided for a scintillation camera and a data processor. The apparatus comprises a scintillation detector including an adder and an analyzer for detecting the valid scintillations, a plurality of conversion units each including an analog-to-digital converter for converting intensity signals derived from the valid scintillations into high, accuracy digital values, and controllers for controlling operation of each of the analog-to-digital converters of the conversion units. The method comprises steps of adding the intensity signals generated by the scintillation camera and which are indicative of the scintillations, and analyzing the sum of the intensity signals to determine if the detected scintillations are valid. To select only those values involved in a scintillation event for processing and free up ADCs which are uninvolved to convert future intensity signals, the intensity signals may be compared to a threshold value to allow only those ADCs whose corresponding intensity signal is above the threshold to convert, or a rapid determination of which serial ADCs are involved can be done by allowing all serial ADCs to convert, waiting for a first positive MSB from one of the ADCS, and resetting all ADCs determined to be uninvolved in the event. The converted signals derived from the intensity signals are digital value signals indicative of the valid scintillations computable by the data processor to determine spatial locations of the valid scintillations.

Scintillation data collecting apparatus and method

The discriminator comprises a summing circuit for producing a sum signal from light detectors of a scintillation camera; a slope analysis circuit for analyzing a slope of the sum signal to produce a slope analysis result indicative of a given characteristic change in the slope; a first event characteristic evaluation circuit for producing in response to the slope analysis result and the sum signal a first event characteristic signal representative of an energy of the first event; a second event characteristic evaluation circuit for producing in response to the slope analysis result and the sum signal a second event characteristic signal representative of an energy of the second event; and a validity analyzer circuit for producing a valid event indicator signal in response to the slope analysis result, the first event characteristic signal and the second event characteristic signal. A method of pulsepile discrimination is also disclosed. The valid event indicator signal can indicate the presence of simultaneous events and the number of valid events among the simultaneous events.

Scintillation camera valid event discrimination

The scintillation camera includes a plurality of individually pulsible light emitting devices associated with a number of the photomultiplier tubes. By pulsing the light emitting device, certain ones of the photomultiplier tubes of the camera receive substantial amounts of light. Values from the certain photomultiplier tubes are compared to one another for carrying out an effective gain adjustment of at least one of the certain tubes. The gain calibration is independent of the amount of light emitted from the light emitting devices. There is also provided a method of adjusting the effective gain of the camera by using the readings resulting from a gamma ray induced scintillation instead of the pulsible light emitting devices.

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Pointe-Claire, Canada

Abel Ferreira