Coherent spread-spectrum coded waveforms in synthetic aperture image formation

• US 9,844,359 B2
• Filed: 09/05/2014
• Issued: 12/19/2017
• Est. Priority Date: 09/13/2013
• Status: Active Grant

• Current Assignee: Decision Sciences International Corporation
• Original Assignee: Decision Sciences Medical Company LLC (Decision Sciences International Corporation)
• Inventors: Wegner, Allan
• Primary Examiner(s): Luong, Peter
• Application Number:
  US14/479,249
• Publication Number:
  US 20150080725A1
• Time in Patent Office: 1,201 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 of producing acoustic waveforms in an acoustic imaging device, 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; and

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 spatial positions of an array of transducer elements relative to the target and beam phase center positions of the array,

wherein the transmitted acoustic waveforms and the returned acoustic waveforms produce an enlarged effective aperture of the acoustic imaging device.

2. 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 over an imaging period.

3. The method of claim 2, wherein the controlling the transducer elements includes 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.

4. The method of claim 2, wherein the controlling the transducer elements includes 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.

5. 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.

6. 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.

7. The method of claim 6, wherein the phase parameter is determined from a set of a pseudo-random numbers or from a set of deterministic numbers.

8. 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.

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

10. 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.

11. The method of claim 10, further comprising:

amplifying the RF-based composite waveform.

12. The method of claim 1, further comprising:

amplifying the received returned acoustic waveforms.

13. The method of claim 1, further comprising:

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,

wherein the information includes an amplitude and a phase associated with the corresponding frequency bands of the received composite waveform.

14. The method of claim 13, 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.

15. The method of claim 1, further comprising:

processing the received returned acoustic waveforms to produce an image of at least part of the target.

16. The method of claim 15, further comprising:

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; and

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.

17. The method of claim 15, wherein the processing comprises:

performing axial range compression of the stored received composite waveforms; and

forming a synthetic aperture image by processing each stored block of axial-range compressed data that encompass the effective aperture using one or more frequency- or time-domain processing techniques.

18. A synthetic aperture acoustic waveform imaging system, 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 imaging 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;

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

a user interface unit in communication with the controller unit.

19. The system of claim 18, 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.

20. The system of claim 18, 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.

21. The system of claim 18, 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.

22. The system of claim 18, wherein the processing unit comprises a digital signal processor.

23. The system of claim 18, wherein the controller unit further comprises a master clock that synchronizes time in at least one of the elements of the acoustic waveform imaging system.

24. The system of claim 18, wherein the controller unit is configured to process the information to produce an image of at least part of the target.

25. The system of claim 18, wherein the user interface unit comprises a display that displays the image and a user input terminal to receive user input data including a mode of operation for operation of the system.

26. The system of claim 25, wherein the mode of operation includes at least one of ATS-Mode (Artificial Tissue Staining Mode) for imaging biological tissue 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.

27. The system of claim 25, wherein the mode of operation includes at least one of CAD-Mode (Computer Aided Diagnostic Mode) for imaging biological tissue 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.

28. The system of claim 25, wherein the display is configured to display a color coded image of the biological tissue based on the classified biological tissue types.

29. The system of claim 18, wherein, in transmitting the acoustic waveforms to the target, the controller unit is configured to control the array of transducer elements 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 over an imaging period.

30. The system of claim 18, 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.

31. The system of claim 18, 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.

32. A method of creating an image from an acoustic waveform, comprising:

combining a plurality of coded waveforms corresponding to different frequency bands to produce a composite waveform comprising individual orthogonal wave signals at the different frequency bands, wherein the coded waveforms include a unique frequency with a corresponding phase and amplitude;

producing an acoustic wave using the composite waveform for transmission toward a target from a first spatial position relative to the target, wherein the acoustic wave includes individual acoustic wave signals corresponding to the coded waveforms of the composite waveform;

transmitting the acoustic wave to the target, wherein the individual acoustic wave signals vary in orientation with respect to each other so that the target receives the individual acoustic wave signals with different waveform orientations over an imaging period;

receiving returned acoustic signals from at least part of the target after the transmitted acoustic wave is sent to the target;

repeating the combining step, the producing step, and the transmitting step from at least a second position relative to the target, wherein the combining, producing, and transmitting steps are repeated for plurality of positions to form a synthetic aperture;

converting the received returned acoustic signals from the plurality of positions into corresponding digital composite waveforms each comprising information of the target; and

processing the received composite waveforms to produce an image of at least part of the target.

33. The method of claim 32, further comprising:

processing the received composite waveforms in real time to produce a synthetic aperture image.

34. The method of claim 33, further comprising:

steering a direction of the transmitted acoustic waves, based on the produced synthetic aperture image, at one or more positions of the plurality of positions in a direct path toward the target.

35. A method of creating an image from an acoustic waveform, comprising:

combining a plurality of coded waveforms corresponding to different frequency bands to produce a composite waveform comprising individual orthogonal wave signals at the different frequency bands, wherein the coded waveforms include a unique frequency with a corresponding phase and amplitude;

producing an acoustic wave formed of individual acoustic wave signals corresponding to the coded waveforms of the composite waveform for transmission toward a target;

transmitting the acoustic wave to the target, wherein the individual acoustic wave signals are transmitted from a first set of beam phase center positions at one or more spatial positions relative to the target, and wherein the individual acoustic wave signals vary in orientation with respect to each other so that the target receives the individual acoustic wave signals with different waveform orientations over an imaging period;

receiving returned acoustic signals from at least part of the target after the transmitted acoustic wave is sent to the target;

repeating the combining step, the producing step, and the transmitting step from at least a second set of beam phase center positions relative to the target at the one or more spatial positions relative to the target, thereby forming a synthetic aperture;

converting the received returned acoustic signals into corresponding digital composite waveforms each comprising information of the target; and

processing the received composite waveforms to produce an image of at least part of the target.

36. The method of claim 35, further comprising:

processing the received composite waveforms in real time to produce a synthetic aperture image.

37. The method of claim 36, further comprising:

steering a direction of the transmitted acoustic waves based on the produced synthetic aperture image.

38. A synthetic aperture acoustic waveform imaging system, 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 transmitter array of transducer elements in communication with the waveform generation 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, wherein the transmitting positions include one or both of spatial positions of the transmitter array and beam phase center positions of the transducer elements of the transmitter array;

a receiver array of transducer elements in communication with the waveform generation unit to receive at one or more receiving positions relative to the target returned acoustic waveforms corresponding to the transmitted acoustic waveforms that return from at least part of the target, wherein the transmitted acoustic waveforms and received acoustic waveforms produce an enlarged effective aperture of the synthetic aperture acoustic waveform imaging system, and wherein the transmitting positions and the receiving positions each include one or both of spatial positions and beam phase center positions;

a first multiplexing unit and a second multiplexing unit in communication with the transmitter array and receiver array, respectively, to select one or more of the transducing elements of the transmitter 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 receiver array to receive the returned acoustic waveforms;

an array of analog to digital (A/D) converters to convert the received returned acoustic waveforms that are received by the receiver 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

a user interface unit in communication with the controller unit.

39. The system of claim 38, 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 transmitter array and the receiver array in the one or more transmitting and receiving positions, respectively.

40. The system of claim 38, 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.

41. The system of claim 38, further comprising:

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

42. The system of claim 38, wherein the processing unit comprises a digital signal processor.

43. The system of claim 38, wherein the controller unit further comprises a master clock that synchronizes time in at least one of the elements of the acoustic waveform imaging system.

44. The system of claim 38, wherein the controller unit is configured to process the information to produce an image of at least part of the target.

45. The system of claim 38, wherein the user interface unit comprises a display that displays the image and a user input terminal to receive user input data including a mode of operation for operation of the system.

46. The system of claim 45, wherein the mode of operation includes at least one of ATS-Mode (Artificial Tissue Staining Mode) for imaging biological tissue 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.

47. The system of claim 45, wherein the mode of operation includes at least one of CAD-Mode (Computer Aided Diagnostic Mode) for imaging biological tissue 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.

48. The system of claim 45, wherein the display is configured to display a color coded image of the biological tissue based on the classified biological tissue types.

49. The system of claim 38, wherein, in transmitting the acoustic waveforms to the target, the controller unit is configured to control the transmitter array 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 over an imaging period.

50. The system of claim 38, wherein the transmitter array of transducer elements is operable for moving in one dimension, two dimensions, or three dimensions along the plurality of positions to transmit the plurality of acoustic waveforms.

51. The system of claim 38, wherein one or more transducer elements of the transmitter array is capable of moving separately in the one dimension, two dimensions, or three dimensions from the other transducer elements of the transmitter array.

52. The system of claim 38, wherein the receiver array of transducer elements is operable for moving in one dimension, two dimensions, or three dimensions along the plurality of positions to receive the returned acoustic waveforms.

53. The system of claim 38, wherein one or more transducer elements of the receiver array is capable of moving separately in the one dimension, two dimensions, or three dimensions from the other transducer elements of the transmitter array.

54. The system of claim 38, wherein the number of transducer elements of the transmitter array is greater than the number of transducer elements of the receiver array.