Coherent spread-spectrum coded waveforms in synthetic aperture image formation

• US 10,321,889 B2
• Filed: 11/06/2017
• Issued: 06/18/2019
• Est. Priority Date: 09/13/2013
• Status: Active Grant

• Current Assignee: Decision Sciences International Corporation
• Original Assignee: Decision Sciences International Corporation
• Inventors: Wegner, Allan
• Primary Examiner(s): Luong, Peter
• Application Number:
  US15/804,955
• Publication Number:
  US 20180206817A1
• Time in Patent Office: 589 Days
• CPC Class Codes: A61B 8/14 Echo-tomography
• CPC Class Codes: A61B 8/4461 Features of the scanning mechanism, e.g. for moving the transducer within the housing of the probe
• CPC Class Codes: A61B 8/4488 the transducer being a phased array
• CPC Class Codes: A61B 8/4494 characterised by the arrangement of the transducer elements devices for short-range imaging using particular transducer elements arrangements under G01S15/8909; arrangements of transducers in generation of mechanical vibrations of infrasonic, sonic or ultrasonic frequency B06B1/0607
• CPC Class Codes: A61B 8/463 characterised by displaying multiple images or images and diagnostic data on one display composite display in devices for short-range imaging with acoustic waves G01S7/52074
• CPC Class Codes: A61B 8/5223 for extracting a diagnostic or physiological parameter from medical diagnostic data for algorithms to analyse biomedical images G06T7/0012
• CPC Class Codes: A61B 8/54 Control of the diagnostic device
• CPC Class Codes: G01S 15/8913 using separate transducers for transmission and reception
• CPC Class Codes: G01S 15/8915 using a transducer array
• CPC Class Codes: G01S 15/8927 using simultaneously or sequentially two or more subarrays or subapertures
• CPC Class Codes: G01S 15/8945 using transducers mounted for linear mechanical movement
• CPC Class Codes: G01S 15/8959 using coded signals for correlation purposes
• CPC Class Codes: G01S 15/8997 using synthetic aperture techniques

Abstract

Techniques, systems, and devices are disclosed for synthetic aperture ultrasound imaging using spread-spectrum, wide instantaneous band, coherent, coded waveforms. In one aspect, a method includes synthesizing a composite waveform formed of a plurality of individual orthogonal coded waveforms that are mutually orthogonal to each other, correspond to different frequency bands and including a unique frequency with a corresponding phase; transmitting an acoustic wave based on the composite waveform toward a target from one or more transmitting positions; and receiving at one or more receiving positions acoustic energy returned from at least part of the target corresponding to the transmitted acoustic waveforms, in which the transmitting and receiving positions each include one or both of spatial positions of an array of transducer elements relative to the target and beam phase center positions of the array, and the transmitted acoustic waveforms and the returned acoustic waveforms produce an enlarged effective aperture.

Claims

1. A method for producing spatial and Doppler information of a target material using synthetic aperture ultrasound, comprising:

synthesizing, in one or more waveform synthesizers, one or more composite waveforms to be transmitted toward a target, wherein a composite waveform is formed of a plurality of individual orthogonal coded waveforms that are mutually orthogonal to each other and correspond to different frequency bands, such that each of the individual orthogonal coded waveforms includes a unique frequency with a corresponding phase;

transmitting, from one or more transmitting positions relative to the target, one or more composite acoustic waveforms comprising a plurality of acoustic waveforms, wherein the transmitting includes selecting one or more transducing elements of an array to transduce the plurality of individual orthogonal coded waveforms of the respective one or more composite waveforms into the plurality of corresponding acoustic waveforms of the respective one or more composite acoustic waveforms;

receiving, at one or more receiving positions relative to the target, returned acoustic waveforms that are returned from at least part of the target corresponding to the transmitted acoustic waveforms, wherein the receiving includes selecting at least some of the transducing elements of the array to receive the returned acoustic waveforms,

wherein the transmitting positions and the receiving positions each include one or both of (i) spatial positions of transducer elements in an array of transducer elements relative to the target and (ii) beam phase center positions of the array of transducer elements, and render an enlarged effective aperture with respect to the array of transducing elements; and

producing waveform data of at least part of the target from the received returned acoustic waveforms relative to corresponding transmitted composite acoustic waveforms, wherein the waveform data includes a data set including spatial data and associated Doppler frequency shift data for each frequency component from the received returned acoustic waveforms corresponding to the individual orthogonal coded waveforms.

2. The method of claim 1, wherein the producing waveform data includes:

converting the received returned acoustic waveforms from analog format to digital format as one or more received composite waveforms corresponding to the one or more composite waveforms, each received composite waveform comprising information of the target,

multiplying a digitized received returned acoustic waveform by a complex conjugate replica of the corresponding transmitted composite acoustic waveform, wherein the complex conjugate replica is time shifted for at least one time shift and the corresponding transmitted composite acoustic waveform is in digital form, and

filtering the products of the multiplying to produce the waveform data.

3. The method of claim 2, comprising:

storing the one or more composite waveforms and the corresponding one or more received composite waveforms in a memory map of data blocks, wherein each data block stores the received returned acoustic waveform of the composite waveform for each sample point, the corresponding individual orthogonal coded waveform, and corresponding position data of the one or more transducer elements for the sample point.

4. The method of claim 2, wherein the information includes an amplitude and a phase associated with the corresponding frequency bands of the received composite waveform, and wherein at least one of the amplitude or the phase is individually amplitude weighted or phase weighted, respectively, for at least one frequency band of the corresponding frequency bands of the received composite waveform.

5. The method of claim 1, wherein the spatial data includes amplitude data of the received returned acoustic waveforms and position data of the received returned acoustic waveforms that corresponds to locations at the target from where the received returned acoustic waveforms originated.

6. The method of claim 5, wherein the waveform data further includes a temporal-spatial data set including time delay rate history data that corresponds to time points associated with the reflection or scattering of the received returned acoustic waveforms from the locations at the target.

7. The method of claim 5, wherein the waveform data further includes a spectral response data set including the Doppler frequency shift data of the target over a selected duration of time.

8. The method of claim 7, wherein the Doppler frequency shift data over the selected duration of time in the spectral response data set is associated with the position data of the received returned acoustic waveforms corresponding to locations at the target from where the received returned acoustic waveforms originated.

9. The method of claim 1, wherein, in transmitting the acoustic waveforms to the target, controlling the transducer elements of the array to cause the composite waveforms to change in orientation with respect to the target so that the target receives the acoustic waveforms at different waveform orientations.

10. The method of claim 9, wherein the controlling the transducer elements includes one or both of (i) translating the array along the plurality of spatial positions relative to the target to cause the change in orientation of the composite waveform with respect to the target, and (ii) changing the beam phase center positions of the transmitted acoustic waveforms on the one or more transducer elements of the array to cause the change in orientation of the composite waveform with respect to the target.

11. The method of claim 1, wherein each waveform of the plurality of individual orthogonal coded waveforms includes a plurality of amplitudes and a plurality of phases that are individually amplitude weighted and individually phase weighted, respectively.

12. The method of claim 1, wherein the synthesizing the individual orthogonal coded waveforms of the composite waveform includes selecting the frequency bands, and determining one or more amplitudes, a time-bandwidth product parameter, and a phase parameter of each individual orthogonal coded waveform.

13. The method of claim 12, wherein the phase parameter is determined from a set of a pseudo-random numbers or from a set of deterministic numbers.

14. The method of claim 1, wherein the transmitting the plurality of the acoustic waveforms includes sequentially or simultaneously transmitting the acoustic waveforms from at least one position of the plurality of positions.

15. The method of claim 1, wherein the individual orthogonal coded waveforms include coherent waveforms.

16. The method of claim 1, further comprising:

forming a radio frequency (RF) waveform based on the composite waveform,

wherein in the transmitted acoustic waveforms are generated by transducing the RF-based composite waveform at the one or more transducer elements of the array.

17. A synthetic aperture acoustic waveform system for producing spatial and Doppler information of a target material, comprising:

a waveform generation unit comprising one or more waveform synthesizers coupled to a waveform generator, wherein the waveform generation unit synthesizes a composite waveform comprising a plurality of individual orthogonal coded waveforms corresponding to different frequency bands that are generated by the one or more waveform synthesizers according to waveform information provided by the waveform generator, wherein the individual orthogonal coded waveforms are mutually orthogonal to each other and correspond to different frequency bands, such that each of the individual orthogonal coded waveforms includes a unique frequency with a corresponding phase;

a transmit/receive switching unit that switches between a transmit mode and a receive mode;

an array of transducer elements in communication with the transmit/receive switching unit to transmit a composite acoustic waveform comprising a plurality of acoustic waveforms from one or more transmitting positions relative to the target, the transmitted acoustic waveforms of the composite acoustic waveform based on the synthesized individual orthogonal coded waveforms of the composite waveform, and to receive at one or more receiving positions relative to the target returned acoustic waveforms corresponding to the plurality of transmitted acoustic waveforms that return from at least part of the target, wherein the transmitted acoustic waveforms and the returned acoustic waveforms produce an enlarged effective aperture of the synthetic aperture acoustic waveform system, and wherein the transmitting positions and the receiving positions each include one or both of spatial positions and beam phase center positions;

a multiplexing unit in communication with the array of transducer elements to select one or more transducing elements of an array to transduce the plurality of individual orthogonal coded waveforms into the plurality of corresponding acoustic waveforms, and to select one or more transducing elements of the array to receive the returned acoustic waveforms; and

an array of analog to digital (A/D) converters to convert the received returned acoustic waveforms that are received by the array of transducer elements from analog format to digital format, wherein the received returned acoustic waveforms provide information of the target;

a controller unit in communication with the waveform generation unit and the array of A/D converters, the controller unit comprising a memory unit to store data and a processing unit coupled to the memory unit to process the information as data and produce waveform data of at least part of the target,

wherein the waveform data includes a data set including spatial data and associated Doppler frequency shift data for each frequency component from the received returned acoustic waveforms corresponding to the individual orthogonal coded waveforms.

18. The system of claim 17, further comprising:

a user interface unit including a display in communication with the controller unit to display the waveform data.

19. The system of claim 18, wherein the user interface unit is operable to receive input from an operator of the system, the mode of operation including:

an ATS-Mode (Artificial Tissue Staining Mode) to characterize biological tissue of the target that enables image color coding based on at least one feature of one or more measured properties that are obtained from the returned acoustic waveform, or

a CAD-Mode (Computer Aided Diagnostic Mode) to characterize biological tissue of the target that uses one or more algorithmic classifiers to classify biological tissue types using at least one feature of one or more measured properties that are obtained from the returned acoustic waveform.

20. The system of claim 19, wherein the display of the user interface is operable to display a color coded image of biological tissue of the target based on the classified biological tissue types.

21. The system of claim 17, wherein the waveform generation unit further comprises one or more amplifiers, configured between the transmit/receive switching unit and the one or more waveform synthesizers, which modifies the composite waveform.

22. The system of claim 17, further comprising:

an array of one or more pre-amplifiers, configured between the transmit/receive switching unit and the array of A/D converters, which modifies the received returned acoustic waveform.

23. The system of claim 17, wherein the processing unit comprises a digital signal processor.

24. The system of claim 17, wherein the controller unit is configured to control the array of transducer elements, in transmitting the acoustic waveforms to the target, to cause the composite waveform to change in orientation with respect to the target so that the target receives the composite acoustic waveform with different waveform orientations.

25. The system of claim 17, wherein the array of transducer elements is operable for moving in one dimension, two dimensions, or three dimensions along the transmitting positions to transmit the plurality of acoustic waveforms and along the receiving positions to receive the returned acoustic waveforms.

26. The system of claim 17, wherein at least one of the transducer elements of the array is capable of moving separately in the one dimension, two dimensions, or three dimensions from the other transducer elements of the transmitter array.

27. The system of claim 17, wherein the controller unit further comprises a master clock that synchronizes time in at least one of the elements of the synthetic aperture acoustic waveform system.

28. The system of claim 17, wherein the stored data includes the digital format of the received returned acoustic waveforms, the corresponding synthesized composite waveform, and corresponding position data of the array of transducers elements in the one or more transmitting and receiving positions.

29. The system of claim 17, wherein the spatial data includes amplitude data of the received returned acoustic waveforms and position data of the received returned acoustic waveforms that corresponds to locations at the target from where the received returned acoustic waveforms originated.

30. The system of claim 29, wherein the waveform data further includes a temporal-spatial data set including time delay rate history data that corresponds to time points associated with the reflection or scattering of the received returned acoustic waveforms from the locations at the target.

31. The system of claim 29, wherein the waveform data further includes a spectral response data set including the Doppler frequency shift data of the target over a selected duration of time.

32. The system of claim 31, wherein the Doppler frequency shift data over the selected duration of time in the spectral response data set is associated with the position data of the received returned acoustic waveforms corresponding to locations at the target from where the received returned acoustic waveforms originated.