Method and apparatus for coherent imaging system
First Claim
1. A medical imaging system for generating a stream of digital data signals with a vibrating energy beam having increased dynamic range which represents at least one object point detected in the object region including:
- (a) an array of transducer elements which produces bipolar analog echo signals from impingement with at least one object point in the object region,(b) means to process the analog echo signals with at least one analog-to-digital converter device so that a stream of digital data signals is obtained from the analog-to-digital converter device bearing a mathematical relationship to the analog echo signals which approximates a non-linear amplitude compression function,(c) means to non-linearly process the stream of compressed amplitude digital data signals from the analog-to-digital converter device in accordance with the inverse of the previously employed mathematical function and thereby gain expanded amplitude digital data signals which are linearly related to the analog echo signals,(d) means for delaying the stream of digital data signals after amplitude compression by respective predetermined time intervals corresponding to the distance of the detected object point from the respective transducer elements which causes each data signal to occur at substantially the same time, and(e) means to obtain a summation of the delayed expanded amplitude digital data signals.
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Abstract
A method and apparatus for improved digital processing of the analog echo signals in a coherent imaging system is described which simplifies the channel circuitry requirements. The analog echo signals detected with a phased array of transducer elements are first compressed in a non-linear manner then expanded non-linearly with analog-to-digital converter means to provide increased instantaneous dynamic range in the overall system. Representative phased array coherent imaging systems having the improved digital processing means are also disclosed.
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Citations
55 Claims
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1. A medical imaging system for generating a stream of digital data signals with a vibrating energy beam having increased dynamic range which represents at least one object point detected in the object region including:
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(a) an array of transducer elements which produces bipolar analog echo signals from impingement with at least one object point in the object region, (b) means to process the analog echo signals with at least one analog-to-digital converter device so that a stream of digital data signals is obtained from the analog-to-digital converter device bearing a mathematical relationship to the analog echo signals which approximates a non-linear amplitude compression function, (c) means to non-linearly process the stream of compressed amplitude digital data signals from the analog-to-digital converter device in accordance with the inverse of the previously employed mathematical function and thereby gain expanded amplitude digital data signals which are linearly related to the analog echo signals, (d) means for delaying the stream of digital data signals after amplitude compression by respective predetermined time intervals corresponding to the distance of the detected object point from the respective transducer elements which causes each data signal to occur at substantially the same time, and (e) means to obtain a summation of the delayed expanded amplitude digital data signals. - View Dependent Claims (2, 3, 4, 5)
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6. A medical imaging system for generating a stream of digital data signals with a vibrating energy beam having increased dynamic range which represents at least one object point detected in an object region including:
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(a) an array of transducer elements which produces bipolar analog echo signals from impingement with at least one object point in the object region, (b) bipolar amplification means for compressing the amplitude of the bipolar analog echo signals so that the output signals are non-linearly related to the input signals, (c) analog-to-digital converter means to expand the amplitude of the compressed amplitude analog input signals to a stream of digital data signals having an inverse non-linear relationship to the compressed amplitude analog input signals, (d) means for delaying the stream of digital data signals after amplitude compression by respective predetermined time intervals corresponding to the distance of the detected object point from the respective transducer elements which causes each data signal to occur at substantially the same time, and (e) means to obtain a summation of the delayed expanded amplitude digital signals. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A medical imaging system for generating a stream of digital data signals with an ultrasonic energy beam having increased dynamic range which represents a plurality of object points detected in an object region comprising:
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(a) an array of transducer elements which produces bipolar analog echo voltage signals from impingement with each object point detected in the object region, (b) linear bipolar preamplifier means to increase the amplitude of the analog echo voltage signals to a level permitting detection of object points substantially throughout the entire object region (c) means to process the analog echo voltage signals with at least one analog-to-digital converter device so that a stream of digital data signals is obtained from the analog-to-digital converter device bearing a mathematical relationship to the analog echo voltage signals which approximates a non-linear amplitude compression power function, (d) means to non-linearly process the stream of compressed amplitude digital data signals from the analog-to-digital converter device in accordance with the inverse of the previously employed mathematical power function and thereby obtain expanded amplitude digital data signals which are linearly related to the analog echo voltage signals, (e) means for delaying the expanded amplitude digital data signals by a respective predetermined time interval corresponding to the distance between the transducer elements and the detected object points which causes each data signal to occur at substantially the same time, and (f) means to obtain a summation of the delayed expanded amplitude digital data signals. - View Dependent Claims (21, 22, 23, 24, 25)
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26. A medical imaging system for generating a stream of digital data signals with an ultrasonic energy beam having increased dynamic range which represents a plurality of object points detected in an object region including:
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(a) an array of transducer elements which produces bipolar analog echo voltage signals from impingement with at least one object point in the object region, (b) a pair of demodulator means operatively associated with each transducer element to provide demodulated bipolar echo voltage signals of different relative phase, the demodulator means operating at a predetermined excitation frequency with phase being determined by the product of a predetermined reference angular frequency with a predetermined time interval corresponding to the distance between the respective transducer elements and the detected object points to cause each data signal to occur substantially at the same phase, (c) individual means each having at least one analog-to-digital converter device to separately compress the amplitude of the demodulated analog echo voltage signals and provide separate streams of digital data signals bearing a mathematical relationship to the respective analog echo voltage signals which approximates a non-linear amplitude compression power function, (d) individual means to separately expand each stream of compressed amplitude digital data signals from the respective analog-to-digital converter devices in accordance with the inverse of the previously employed mathematical power function and thereby obtain expanded amplitude digital data signals which are linearly related to the respective analog echo voltage signals, (e) means to separately delay each stream of expanded amplitude digital data signals by a respective predetermined time interval corresponding to the distance between respective transducer elements and detected object points which causes each data signal to occur at substantially the same time, and (f) means to separately sum each stream of delayed expanded amplitude digital data signals to provide a combined signal which is a monotonic function of the square of the individual summed digital data streams. - View Dependent Claims (27, 28, 29, 30, 31, 32)
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33. In a vibratory energy coherent medical imaging system a method of processing the bipolar analog echo signals to provide increased dynamic range comprising the steps of:
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(a) producing analog echo signals with a phased array of transducer elements, (b) processing the analog echo signals with means employing at least one analog-to-digital converter device so that a stream of digital data signals is obtained from the analog-to-digital converter device bearing a mathematical relationship to the analog echo signals which approximates a non-linear amplitude compression function, (c) processing the compressed amplitude analog echo signals from the analog-to-digital converter device in accordance with the inverse of the previously employed mathematical function and thereby obtain expanded amplitude digital data signals which are linearly related to the analog echo signals, (d) time delaying the expanded amplitude digital data signals by respective predetermined time intervals corresponding to the distance of a detected object point from the respective transducer elements which causes each data signal to occur at substantially the same time, and (e) summing the delayed expanded amplitude digital data signals. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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44. In an ultrasonic coherent medical imaging system, a method of processing the bipolar analog echo signals to provide increased dynamic range comprising the steps of:
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(a) producing analog echo voltage singals with a phased array of transducer elements, (b) demodulating the analog echo voltage signals to provide demodulated bipolar analog echo voltage signals of a different phase, the demodulation being provided at a predetermined excitation frequency with phase being determined by the product of a predetermined reference angular frequency and a predetermined time interval corresponding to the distance between respective transducer element and detected object points so as to cause each data signal to occur at substantially the same time, (c) processing each of the demodulated analog echo voltage signals with separate means each having at least one analog-to-digital converter device to separately compress the amplitude of the demodulated analog echo voltage signals and provide separate streams of digital data bearing a mathematical relationship to the respective analog echo voltage signals which approximates a non-linear power function, (d) separately expanding the amplitude of each stream of compressed amplitude digital data signals from the respective analog-to-digital converter devices in accordance with the inverse of the previously employed mathematical power function and thereby obtain individual expanded amplitude digital data signals which are linearly related to the respective analog echo voltage signals, (e) time delaying each stream of expanded amplitude digital data signals by respective predetermined time intervals corresponding to the distance of a detected object point from the respective transducer elements which causes each data signal to occur at substantially the same time, and (f) separately summing each stream of delayed expanded amplitude digital data signals to provide a combined signal which is a monotonic function of the square of the individual summed digital data streams. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55)
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Specification