Method and apparatus for focusing transmission and reception of ultrasonic beams

• US 5,301,674 A
• Filed: 03/27/1992
• Issued: 04/12/1994
• Est. Priority Date: 03/27/1992
• Status: Expired due to Term

• Current Assignee: Diasonics, Inc. (General Electric Company)
• Original Assignee: Diasonics, Inc. (General Electric Company)
• Inventors: Ishrak, Syed O., Erikson, Kenneth R., Spratt, Ray S., Reckwerdt, Wilbur A.
• Primary Examiner(s): JAWORSKI, FRANCIS J
• Application Number:
  US07/859,069
• Time in Patent Office: 746 Days
• Field of Search: 128/660.09, 128/660.07, 128/661.01, 73/625-676
• US Class Current: 600/447
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: G01S 15/8952 using discrete, multiple frequencies
• CPC Class Codes: G01S 7/52046 Techniques for image enhancement involving transmitter or receiver image enhancement by image data processing G06T5/00
• CPC Class Codes: G10K 11/341 Circuits therefor

Abstract

An ultrasound imaging system for performing dynamic focusing of ultrasonic waves during transmit and receive. The present invention includes a method and a means for transmitting ultrasonic waves to a multiple depths within a body. The present invention optimizes the transmit frequency for each of the multiple depths to localize the energy of the ultrasonic waves. The present invention also includes a method and means for performing dynamic receive focusing of the reflected ultrasonic waves produced by discontinuities in the body, such that it is focused to receive ultrasonic waves from the depth at which the transmitted ultrasonic waves are focused.

Claims

1. A method of focusing energy waves during transmission and reception into a body at a plurality of focal points, each of said focal points corresponding to a zone within said body, wherein said energy waves are transmitted from a source into said body according to a set of time delays and transmit parameters and are reflected from discontinuities within said body, said method comprising the steps of:

selecting a plurality of zones, wherein said plurality of zones have a plurality of focal points, wherein each of said plurality of focal points is within one of said plurality of zones;

optimizing the transmit frequency of the energy waves for each of said plurality of zones, such that the energy is localized at said plurality of focal points within said body;

optimizing the bandwidth of the energy waves for each of said plurality of zones, such that the energy is localized at said plurality of focal points within said body;

determining the time delays between transmission necessary to ensure that energy waves subsequently transmitted to one of said focal points do not interfere with the reception of reflected energy waves from the remaining of said plurality of focal points, and

scanning the body along a plurality of scan lines with the energy waves that are transmitted and focused in each of the plurality of zones using the time delays, the transmit frequency and the bandwidth for each of the plurality of zones, such that the energy waves for each of the plurality of zones has a single frequency and bandwidth to localize the energy waves in each of the plurality of zones, wherein the reflected energy waves from zones outside any one of the plurality of zones are reduced in strength when transmitting energy waves to said one of the plurality of zones to avoid interference with the reflected energy waves from said one of the plurality of zones, such that all of the reflected energy waves along one of said plurality of scan lines from one of said plurality of zones is not received before transmitting energy waves to another of said plurality of zones along said one of said plurality of scan lines, such that an image of said object is generated according to said reflected energy waves received from each of the plurality of zones.

2. The method as in claim 1 wherein each of said steps is performed dynamically, such that said said energy waves are focused during transmission and reception in real-time.

3. The method as in claim 1 wherein said energy waves are ultrasonic waves, such that an ultrasound image is generated.

4. The method as in claim 1 wherein said step of optimizing comprises the step of increasing the frequency of said energy waves at depths in the near field of said object.

5. A method of focusing ultrasonic waves at a plurality of focal points and a plurality of lines in a body, each of said focal points corresponding to a zone within said body, wherein said waves are transmitted from a source into said body according to a set of time delays and transmit parameters and are reflected from discontinuities within said body, said method comprising the steps of:

selecting a plurality of zones, wherein said plurality of zones have a plurality of focal points, wherein each of said plurality of focal points is within one of said plurality of zones;

optimizing the transmit frequency of said ultrasonic waves for each of said plurality of zones by increasing the frequency of said waves at depths in the near field of said object, such that the ultrasonic waves are localized at said plurality of focal points within said body;

optimizing the bandwidth of said ultrasonic waves for each of said plurality of zones by increasing the frequency of said waves at depths in the near field of said object, such that the ultrasonic waves are localized at said plurality of focal points within said body;

determining the time delays between transmission necessary to ensure that ultrasonic waves subsequently transmitted to one of said focal points do not interfere with the reception of reflected ultrasonic waves from the remaining of said plurality of focal points, and

scanning the body along a plurality of scan lines with the ultrasonic waves that are transmitted and focused in each of the plurality of zones using the time delays, the transmit frequency and the bandwidth for each of the plurality of zones, such that the ultrasonic waves for each of the plurality of zones has a single frequency and bandwidth to localize the ultrasonic waves in each of the plurality of zones, wherein the reflected ultrasonic waves from zones outside any one of the plurality of zones are reduced in strength when transmitting ultrasonic waves to said one of the plurality of zones to avoid interference with the reflected ultrasonic waves from said one of said plurality of zones, such that all of the reflected ultrasonic waves along one of said plurality of scan lines from one of said plurality of zones is not received before transmitting ultrasonic waves to another of said plurality of zones along said one of said plurality of scan lines, such that an image of said object is generated according to said reflected ultrasonic waves.

6. The method as in claim 5 wherein each of said steps is performed dynamically, such that said said energy waves are focused during transmission and reception in real-time.

7. The method as in claim 5 further comprising the step of optimizing the intensity of said waves for said plurality of zones by increasing the intensity of waves for the deeper of said plurality of zones.

8. The method as defined in claim 5 further comprising the step of performing mix line sequencing, such that after the reflected ultrasonic waves from one of said plurality of focal point on one of said lines is received, the ultrasonic waves are transmitted to one of said plurality of focal points on another of said lines.

9. The method as defined in claim 5 further comprising the step of maintaining constant and small phase errors at the boundaries between each of said plurality of zones, such that banding is prevented.

10. An apparatus for generating an image of an object having discontinuities comprising:

transmitter means for transmitting energy waves for imaging at a plurality of depths within said object, wherein the transmitter means includes means for optimizing the frequency of said energy waves for each of said plurality of depths and means for optimizing the bandwidth for each of said plurality of depths, wherein the transmitter means includes means for scanning the object along a plurality of scan lines with the energy waves, such that each of the plurality of depths has a single frequency and bandwidth to localize the energy waves at each of the plurality of depths, wherein the reflected energy waves from zones outside any one of the plurality of depths are reduced in strength when transmitting energy waves to said one of the plurality of depths to avoid interference with the reflected energy waves from said one of said plurality of depths, such that all of the reflected energy waves along one of said plurality of scan lines from one of said plurality of depths is not received before transmitting energy waves to another of said plurality of depths along said one of said plurality of scan lines. such that said waves are localized at said plurality of depths when transmitted during scanning of the object; and

receiving means for receiving reflected energy waves corresponding to reflections of energy waves from the discontinuities within a given depth, wherein an image of said object is generated according to said reflected energy waves received by said receiving means.

11. The apparatus as defined in claim 10 wherein said transmitter means focuses said waves dynamically, such that the image of said object is generated in real-time.

12. The apparatus as defined in claim 10 wherein said transmitter means optimizes the frequency for each of said plurality of depths by varying said frequency with depth, such that the frequency is increased for depths nearer into said object.

13. An apparatus for generating an ultrasonic image of an object having discontinuities comprising:

transmitter means for transmitting ultrasonic waves for imaging at a plurality of depths within an object, wherein the transmitter means includes means for dynamically focusing said ultrasonic waves at said plurality of depths, said means for dynamically focusing said ultrasonic waves includes means for optimizing the frequency of said ultrasonic waves for each of the plurality of depths and means for optimizing the bandwidth for each of the plurality of depths, such that each of the plurality of depths has a single frequency and bandwidth to localize the energy waves at each of the plurality of depths, wherein the reflected ultrasonic waves from depths outside any one of the plurality of depths are reduced in strength when transmitting the ultrasonic waves to said one of the plurality of depths to avoid interference with the reflected ultrasonic waves from said one of the plurality of depths, wherein the frequency is varied for each of plurality of depths, such that the frequency of said ultrasonic waves is increased for depths nearer into said object in order to optimize the transmit frequency for each of said plurality of depths to localize the ultrasonic waves when transmitted during scanning of the object, wherein the transmitter means scans the object along a plurality of scan lines using the ultrasonic waves, such that all of the reflected energy waves along one of said plurality of scan lines from one of said plurality of depths is not received before transmitting energy waves to another of said plurality of depths along said one of said plurality of scan lines; and

receiving means for receiving reflected ultrasonic waves corresponding to reflections of ultrasonic waves from the discontinuities within a given depth, wherein an image of said object is generated in real-time according to said reflected ultrasonic waves received by said receiving means.

14. The apparatus as defined in claim 13 wherein said receiving means dynamically focuses on the reflected ultrasonic waves.

15. The apparatus as defined in claim 13 wherein said transmitter means optimizes the intensity of said waves for said plurality of zones by increasing the intensity of waves for the deeper of said plurality of zones.

16. A method of focusing energy waves in a body at a plurality of focal points and a plurality of lines, each of said focal points corresponding to a zone within said body, wherein said waves are transmitted from a source into said body according to a set of time delays and transmit parameters and are reflected from discontinuities within said body, said method comprising the steps of:

selecting a plurality of zones, wherein said plurality of zones have a plurality of focal points, wherein each of said plurality of focal points is associated with one of said plurality of zones, such that the energy is focused at said plurality of focal points within said body;

optimizing the transmit frequency of the energy waves for each of said plurality of zones, such that the energy is localized at said plurality of focal points within said body;

optimizing the bandwidth of the energy waves for each of said plurality of zones, such that the energy is localized at said plurality of focal points within said body;

maintaining the aperture size of said waves, such that the size of said plurality of zones remains small during transmission; and

determining the transmit time delays necessary to ensure that energy waves subsequently transmitted to one of said focal points do not interfere with the reception of reflected energy waves from the remaining of said plurality of focal points, and

scanning the body along a plurality of scan lines with the energy waves that are transmitted and focused in each of the plurality of zones using the time delays, the transmit frequency and the bandwidth for each of the plurality of zones, such that the energy waves for each of the plurality of zones has a single frequency and bandwidth to localize the energy waves in each of the plurality of zones, wherein the reflected energy waves from zones outside any one of the plurality of zones are reduced in strength when transmitting energy waves to said one of the plurality of zones to avoid interference with the reflected energy waves from said one of said plurality of zones, such that all of the reflected energy waves along one of said plurality of scan lines from one of said plurality of zones is not received before transmitting energy waves to another of said plurality of zones along said one of said plurality of scan lines, wherein an image of said object is generated according to said reflected energy waves received from each of the plurality of zones.

17. The method as defined in claim 16 wherein said step of maintaining comprises maintaining a low and constant f-number.

18. The method as defined in claim 16 wherein the aperture size for transmitting the energy waves is limited to a maximum available aperture and wherein said step of maintaining further comprises the step of making the zones larger once the maximum available aperture has been used.

19. The method as defined in claim 16 further comprising the step of performing mix line sequencing, such that after the reflected energy waves from one of said plurality of focal points on one of said lines is received, the energy waves are transmitted to one of said plurality of focal points on another of said lines.

20. A method of focusing energy waves into a body at a plurality of focal points, each of said focal points corresponding to a zone within said body, wherein said waves are transmitted from a source into said body according to a set of time delays and transmit parameters and are reflected from discontinuities within said body, said method comprising the steps of:

selecting a plurality of zones, wherein said plurality of zones have a plurality of focal points, wherein each of said plurality of focal points is associated with one of said plurality of zones, such that the energy is localized at said plurality of focal points within said body;

optimizing the transmit frequency of the energy waves for each of said plurality of zones, such that the energy is localized at said plurality of focal points within said body;

optimizing the bandwidth of the energy waves for each of said plurality of zones, such that the energy is localized at said plurality of focal points within said body;

maintaining the aperture size of said waves, such that the size of said plurality of zones remains small during transmission;

determining the time delays between transmission necessary to ensure that energy waves subsequently transmitted to one of said focal points do not interfere with the reception of reflected energy waves from the remaining of said plurality of focal points; and

scanning the body along a plurality of scan lines with the energy waves that are transmitted and focused in each of the plurality of zones using the time delays, the transmit frequency and the bandwidth for each of the plurality of zones, such that the energy waves for each of the plurality of zones has a single frequency and bandwidth to localize the energy waves in each of the plurality of zones, wherein the reflected energy waves from zones outside any one of the plurality of zones are reduced in strength when transmitting energy waves to said one of the plurality of zones to avoid interference with the reflected energy waves from said one of the plurality of zones, such that all of the reflected energy waves along one of said plurality of scan lines from one of said plurality of zones is not received before transmitting energy waves to another of said plurality of zones along said one of said plurality of scan lines, wherein the step of scanning includes the step of selectively filtering the reflected energy waves during reception, such that an image of said object is generated according to said reflected energy waves.

21. The method as defined in claim 20 wherein said step of filtering comprises the step of filtering the low frequencies of said reflected energy waves for each of said plurality of zones.

22. A method of focusing energy waves in a body at a plurality of focal points, each of said focal points corresponding to a zone within said body, wherein said waves are transmitted from a source into said body according to a set of time delays and transmit parameters and are reflected from discontinuities within said body, said method comprising the steps of:

selecting a plurality of zones, wherein said plurality of zones have a plurality of focal points, wherein each of said plurality of focal points is associated with one of said plurality of zones;

optimizing the transmit frequency of the energy waves for each of said plurality of zones, such that the energy is localized at said plurality of focal points within said body;

varying the bandwidth of said waves for each of said plurality of zones during transmission, such that the energy is localized at said plurality of focal points within said body, wherein said step of varying said bandwidth comprises the step of varying the burst length of said waves during transmission;

maintaining the aperture size of said waves, such that the size of said plurality of zones remains small during transmission; and

determining the time delays necessary to ensure that energy waves subsequently transmitted to one of said focal points do not interfere with the reception of reflected energy waves from the remaining of said plurality of focal points, and

scanning the body along a plurality of scan lines with the energy waves that are transmitted and focused in each of the plurality of zones using the time delays, the transmit frequency and the bandwidth for each of the plurality of zones, such that the energy waves for each of the plurality of zones has a single frequency and bandwidth to localize the energy waves in each of the plurality of zones, wherein the reflected energy waves from zones outside any one of the plurality of zones are reduced in strength when transmitting energy waves to said one of the plurality of zones to avoid interference with the reflected energy waves from said one of the plurality of zones, such that all of the reflected energy waves along one of said plurality of scan lines from one of said plurality of zones is not received before transmitting energy waves to another of said plurality of zones along said one of said plurality of scan lines, wherein the step of scanning includes the step of receiving the reflected energy waves, such that an image of said object is generated according to said reflected energy waves.

23. The method as in claim 22 wherein each of said steps is performed dynamically, such that said said energy waves are focused during transmission and reception in real-time.

24. The method as in claim 22 wherein said energy waves are ultrasonic waves, such that an ultrasound image is generated.

25. The method as in claim 22 wherein said step of varying the burst length comprises the step of reducing the burst length of said waves at depths in the near field of said object.

26. The method as in claim 22 further comprising the step of optimizing the intensity of said energy waves for said plurality of zones by increasing the intensity of said energy waves for the deeper of said plurality of zones.

27. A method of focusing ultrasonic waves in a body at a plurality of focal points and a plurality of lines, each of said focal points corresponding to a zone within said body, wherein said waves are transmitted from a source into said body according to a set of time delays and transmit parameters and are reflected from discontinuities within said body, said method comprising the steps of:

selecting a plurality of zones, wherein said plurality of zones have a plurality of focal points, wherein each of said plurality of focal points is associated with one of said plurality of zones;

optimizing the transmit frequency of the ultrasonic waves for each of said plurality of zones, such that the ultrasonic waves are localized at said plurality of focal points within said body;

optimizing the bandwidth of said ultrasonic waves for each of said plurality of zones by reducing the burst length of said waves at depths in the near field of said object, such that the ultrasonic waves is localized at said plurality of focal points within said body;

maintaining the aperture size of said waves, such that the size of said plurality of zones remains small during transmission;

determining the time delays necessary to ensure that ultrasonic waves subsequently transmitted to one of said focal points do not interfere with the reception of reflected ultrasonic waves from the remaining of said plurality of focal points, and

scanning the body along a plurality of scan lines with the ultrasonic waves that are transmitted and focused in each of the plurality of zones using the time delays, the transmit frequency and the bandwidth for each of the plurality of zones, such that the ultrasonic waves for each of the plurality of zones has a single frequency and bandwidth to localize the ultrasonic waves in each of the plurality of zones, wherein the reflected ultrasonic waves from zones outside any one of the plurality of zones are reduced in strength when transmitting ultrasonic waves to said one of the plurality of zones to avoid interference with the reflected ultrasonic waves of said one of the plurality of zones, such that all of the reflected ultrasonic waves along one of said plurality of scan lines from one of said plurality of zones is not received before transmitting ultrasonic waves to another of said plurality of zones along said one of said plurality of scan lines, wherein the step of scanning includes the step of receiving the reflected energy waves, such that an image of said object is generated according to said reflected ultrasonic waves.

28. The method as in claim 27 wherein each of said steps is performed dynamically, such that said ultrasonic waves are focused during transmission and reception in real-time.

29. The method as defined in claim 27 further comprising the step of performing mix line sequencing, such that after the reflected ultrasonic waves from one of said plurality of focal point on one of said lines is received, the ultrasonic waves are transmitted to one of said plurality of focal points on another of said lines.

30. An apparatus for generating an image on an object having discontinuities comprising:

transmitter means for transmitting energy waves for imaging at a plurality of depths within an object, wherein the transmitter means includes means for optimizing the bandwidth of said energy waves for each of said plurality of depths, means for optimizing the frequency for each of said plurality of depths, and means for maintaining the aperture, wherein the transmitter means transmits the energy waves into the object along a plurality of scan lines, such that each of the plurality of depths has a single frequency and bandwidth to localize the energy waves at each of the plurality of depths while maintaining the aperture, wherein the reflected energy waves from depths outside any one of the plurality of depths are reduced in strength when transmitting energy waves to said one of the plurality of depths to avoid interference with the reflected energy waves from said one of said plurality of depths, such that all of the reflected energy waves along one of said plurality of scan lines from one of said plurality of depths is not received before transmitting energy waves to another of said plurality of depths along said one of said plurality of scan lines, such that said waves are localized to said plurality of depths; and

receiving means for receiving reflected energy waves corresponding to reflections of energy waves from the discontinuities within a given depth, wherein an image of said object is generated according to said reflected energy waves received by said receiving means.

31. The apparatus as defined in claim 30 wherein said transmitting means focuses said waves dynamically, such that the image of said object is generated in real-time.

32. The apparatus as defined in claim 30 wherein said bandwidth is optimized for each of said plurality of depths by varying burst length with depth, such that the burst length is reduced for depths nearer into said object.

33. An apparatus for generating an ultrasonic image on an object having discontinuities comprising:

transmitter means for transmitting ultrasonic waves for imaging at a plurality of depths within an object, wherein the transmitter means includes means for dynamically focusing said ultrasonic waves at said plurality of depths, such that the ultrasonic waves are localized for each of said plurality of depths, wherein the means for dynamically focusing includes means for optimizing the bandwidth of said ultrasonic waves, wherein the burst length is varied, such that the burst length of said ultrasonic waves is reduced for depths nearer into said object in order to optimize the transmit frequency for each of said plurality of depths, and wherein the means for dynamically focusing includes means for optimizing the frequency for each of said plurality of depths and means for maintaining the aperture, wherein the transmitter means transmits the ultrasonic waves into the object along a plurality of scan lines, such that each of the plurality of depths has a single frequency and bandwidth to localize the ultrasonic waves at each of the plurality of depths while maintaining the aperture, wherein the reflected ultrasonic waves from zones outside any one of the plurality of depths are reduced in strength when transmitting ultrasonic waves to said one of the plurality of depths to avoid interference with reflected ultrasonic waves from said one of the plurality of depths, such that all of the reflected ultrasonic waves along one of said plurality of scan lines from one of said plurality of depths is not received before transmitting ultrasonic waves to another of said plurality of depths along said one of said plurality of scan lines; and

receiving means for receiving reflected ultrasonic waves corresponding to reflections of ultrasonic waves from the discontinuities within a given depth, wherein said receiving means performs focusing of said reflected ultrasonic waves, such that said receiving means is focused to receive ultrasonic waves from the depth at which said transmitting means is focusing the transmission of ultrasonic waves, wherein an image of said object is generated in real-time according to said reflected ultrasonic waves received by said receiving means.

34. The apparatus as defined in claim 33 wherein said receiving means is dynamically focused for receiving said ultrasonic waves.

35. The apparatus as defined in claim 33 wherein said transmitter means optimizes the intensity of said waves for said plurality of zones by increasing the intensity of waves for the deeper of said plurality of zones.

36. A system for producing images of a portion of a body utilizing wave energy which is reflected from reflectors within said body, said portion being comprised of a plurality of zones, said system comprising:

source means for transmitting a plurality of concentrated beam profiles of wave energy into said body, such that each of said plurality of beam profiles is focused at one of said zones within said body, and wherein said plurality of beam profiles are transmitted in a specific temporal order, such that at least one of said beam profiles is transmitted to one of said plurality of zones, said one zone being non-adjacent to the zone of the previously transmitted beam profile, wherein the source means includes

means for optimizing the transmit frequency of the wave energy for each of said plurality of zones, such that the wave energy is localized at said plurality of focal points within said body,

means for optimizing the bandwidth of said wave energy for each of said plurality of zones, such that the wave energy is localized at said plurality of focal points within said body, and

means for maintaining the aperture size of said wave energy, such that the size of said plurality of zones remains small during transmission, wherein the source means concentrates wave energy into the object along a plurality of scan lines, such that each of the plurality of depths has a single frequency and bandwidth to localize the wave energy at each of the plurality of depths while maintaining the aperture, wherein the reflected wave energy from zones outside any one of the plurality of depths are reduced in strength when concentrating wave energy in said one of the plurality of depths to avoid interference with the reflected wave energy from said one of the plurality of depths, such that all of the reflected wave energy along one of said plurality of scan lines from one of said plurality of depths is not received before transmitting wave energy to another of said plurality of depths along said one of said plurality of scan lines, and,

receiving means for receiving the reflected wave energy from said reflectors in said body, wherein said source means transmits the next of said plurality of beam profiles after said receiving means receives the reflected wave energy from the maximum depth of the beam profile preceding said next of said beam profiles.

37. The system as defined in claim 36 wherein said plurality of beam profiles is focused in real-time.

38. The system as in claim 36 wherein the frequency of said next of said beam profiles is lower than the frequency of said beam profile preceding said next of said beam profiles.

39. A method for imaging an object in a body using energy waves, wherein said waves are transmitted from a source into said body according to a set of time delays and transmit parameters and are reflected from discontinuities within said body, said method comprising the steps of:

selecting a plurality of zones, wherein said plurality of zones have a plurality of focal points, wherein each of said plurality of focal points is associated with one of said plurality of zones, such that the energy can be localized at said plurality of focal points within said body;

determining the time delays between transmits necessary to ensure that energy waves subsequently transmitted to one of said focal points do not interfere with the reception of reflected energy waves from the remaining of said plurality of focal points; and

focusing continuously said energy waves in a plane during transmission and reception into a body at said plurality of focal points, including focusing said energy which is out of said plane, such that the size of each of said plurality of zones may be reduced producing an improved focus,

wherein the step of continuously focusing energy waves includes the steps of optimizing the transmit frequency of the energy waves for each of said plurality of zones, such that the energy is localized at said plurality of focal points within said body;

optimizing the bandwidth of the energy waves for each of said plurality of zones, such that the energy is localized at said plurality of focal points within said body;

maintaining the aperture size of said waves, such that the size of said plurality of zones remains small during transmission, such that the energy waves for each of the plurality of zones has a single frequency and bandwidth to localize the energy waves in each of the plurality of zones, wherein the reflected energy waves from zones outside any one of the plurality of zones are reduced in strength when transmitting ultrasonic waves to said one of the plurality of zones, wherein the energy waves are transmitted into the body along a plurality of scan lines and reflected energy waves are produced, such that all of the reflected energy waves along one of said plurality of scan lines from one of said plurality of zones is not received before transmitting energy waves to another of said plurality of zones along said one of said plurality of scan lines, such that an image of said object is generated according to said reflected ultrasonic waves.