Semiconductor gamma-ray camera and medical imaging system
First Claim
1. A signal processor for processing signals generated by a plurality of conditioning and processing channels, each channel operatively coupled to a corresponding detection element which produces electrical pulses indicative of an amount of energy associated with radiation quanta absorbed by the detection element, each channel storing an amplitude of the electrical pulse exceeding a predetermined threshold, and each channel generating an event whenever the electrical pulse exceeds a predetermined threshold, comprising:
- a. means for sampling a stored amplitude of a channel generating an event;
b. means, operatively coupled with the sampling means, for normalizing gain introduced by the channel and the corresponding detection element, wherein the normalization means normalizes the sampled amplitude; and
c. means, coupled with the normalization means, for storing the normalized amplitude.
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Abstract
A high-energy photon imaging system includes an imaging head, a signal processor, a data acquisition system and an image processing computer. The imaging head includes a detector that includes a plurality of closely-packed detection modules. Each detection module includes a plurality of detection elements mounted to a circuit carrier. The detection elements produce electrical pulses having amplitudes indicative of the magnitude of radiation absorbed by the detection elements. The circuit carrier includes channels for conditioning and processing the signals generated by corresponding detection elements and for preparing the processed signals for further processing by a signal processor. Each conditioning and processing channel stores the amplitudes of the detection element electrical pulses exceeding a predetermined threshold. The detection modules employ a fall-through circuit which automatically finds only those detection elements that have a stored pulse amplitude exceeding the threshold. The fall-through circuit searches for the next detection element and associated channel having a valid event. The signal processor performs diagnostics, gain normalization, and response efficiency normalization functions. The data acquisition system controls the acquisition and processing of data received from the conditioning and processing channels, produces image data based upon the data in a format that is compatible with existing imaging cameras, and transmits the data to the image processing computer. The image processing computer formulates images based upon the processed signals and displays the formulated images on a display device.
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Citations
10 Claims
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1. A signal processor for processing signals generated by a plurality of conditioning and processing channels, each channel operatively coupled to a corresponding detection element which produces electrical pulses indicative of an amount of energy associated with radiation quanta absorbed by the detection element, each channel storing an amplitude of the electrical pulse exceeding a predetermined threshold, and each channel generating an event whenever the electrical pulse exceeds a predetermined threshold, comprising:
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a. means for sampling a stored amplitude of a channel generating an event; b. means, operatively coupled with the sampling means, for normalizing gain introduced by the channel and the corresponding detection element, wherein the normalization means normalizes the sampled amplitude; and c. means, coupled with the normalization means, for storing the normalized amplitude. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of normalizing electrical pulses generated by a plurality of detection elements, the electrical pulses indicative of an amount of energy associated with radiation quanta absorbed by the detection elements, comprising the steps of:
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a. exposing the detection elements to a uniform radiation field; b. generating a map of the efficiency of each detection element; and c. normalizing the electrical pulses produced by each detection element based upon a peak location in an un-normalized peak height distribution.
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8. A circuit for normalizing gain of signals produced by a plurality of processing channels, comprising:
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a. an analog-to-digital converter having a reference input and an analog input, wherein the analog input is coupled to a signal produced by a selected channel; and b. means, coupled to the reference input, for storing a plurality of gain normalization factors, wherein each channel has a corresponding pre-stored gain normalization factor, and wherein the storage means outputs a gain normalization factor corresponding to the selected channel to the reference input thereby causing the analog-to-digital converter to produce a gain-normalized signal. - View Dependent Claims (9)
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10. A computer program, residing on a computer readable medium, for use in normalizing electrical pulses indicative of an amount of energy associated with radiation quanta absorbed by the detection elements, the computer program comprising executable instructions for causing a computer to:
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a. generate a map of the efficiency of each detection element when the detection elements are exposed to a uniform radiation field; and b. normalize the electrical pulses produced by each detection element based upon a peak location in an unnormalized peak height distribution.
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Specification