Two-dimensional phased array ultrasonic probe and three-dimensional imaging method

Abstract

The application provides an ultrasonic two-dimensional phased array probe and a three-dimensional imaging method. The ultrasonic two-dimensional phased array probe comprises an ultrasonic transmitting module and an ultrasonic receiving module. The ultrasonic transmitting module is used for transmitting ultrasonic wave signals to an imaging medium. The ultrasonic transmitting module comprises a transmitting transducer array and a transmitting circuit module connected with the transmitting transducer array. The transmitting circuit module is used for applying excitation delay and optimizing the power of an output signal. The ultrasonic receiving module is used for receiving echo signals in the imaging medium. The ultrasonic receiving module comprises a receiving transducer array and a receiving circuit module connected with the receiving transducer array. The receiving circuit module is used for optimizing the quality of a received signal. The transmitting transducer array and the receiving transducer array are arranged in a two-dimensional orthogonal manner. The application can greatly reduce the number of array elements and the data volume.

Description

Technical Field

[0001] This application relates to the field of ultrasonic imaging technology, and in particular to an ultrasonic two-dimensional phased array probe and a three-dimensional imaging method. Background Technology

[0002] In the field of ultrasound imaging, two-dimensional phased array probes, due to their ability to achieve flexible beam deflection and focusing, have become one of the core components of three-dimensional ultrasound imaging, and are widely used in medical diagnosis (such as cardiovascular and small organ imaging), industrial inspection, and other scenarios. However, existing two-dimensional phased array probes and their supporting imaging methods still have many technical bottlenecks, making it difficult to balance imaging efficiency, resolution, cost, and signal quality. Specific shortcomings include:

[0003] First, the array structure design is redundant, resulting in high cost and complexity. Existing two-dimensional phased arrays mostly adopt a "area array" structure (i.e., the transmitter and receiver share the same set of two-dimensional array elements). To achieve a large imaging field of view and high resolution, thousands of array elements are required. On the one hand, a large number of array elements leads to complex probe manufacturing processes (such as fine cutting and electrode packaging), significantly increasing production costs; on the other hand, an excessive number of array elements increases the number of signal channels, raising the hardware cost of the transmitter / receiver circuits.

[0004] Second, the array element materials do not match the functional requirements, resulting in low energy conversion efficiency. The core performance of ultrasonic transducer array elements depends on the characteristics of piezoelectric materials. However, in existing technologies, the transmitting and receiving array elements often use the same piezoelectric material (such as the general-purpose PZT-5 series), without addressing the differentiated requirements of "high-efficiency electrical-to-acoustic energy conversion for transmission" and "precise acoustic-to-electrical energy conversion for reception."

[0005] Third, the circuit matching design is simplistic, making it difficult to balance signal quality and power. Existing probes often employ a uniform impedance matching strategy (such as simply pursuing equal impedance magnitudes) in their transmitting / receiving circuits, without optimizing for the core objectives of both types of circuits. If the transmitting circuit does not achieve impedance equalization matching, the excitation signal will suffer reflection loss at the "circuit-element" interface, preventing the maximum power from being transferred to the transmitting element, thereby weakening the ultrasonic output intensity and limiting the imaging depth. If the receiving circuit does not employ a targeted low-noise matching scheme, phase distortion and noise superposition will reduce the fidelity of the received signal, affecting subsequent beamforming and image reconstruction results.

[0006] Fourth, the limited field of view in 3D imaging results in low reconstruction efficiency and low imaging frame rate. Existing 3D imaging methods often employ large-size transducers to ensure a good signal-to-noise ratio, leading to a small sensing angle in specific directions and a limited field of view. Furthermore, current 3D imaging methods face a trade-off between field of view and imaging efficiency—expanding the field of view in 3D space requires a significant increase in the number of transmissions, leading to longer data acquisition times and making it difficult to meet real-time imaging requirements. Summary of the Invention

[0007] The purpose of this application is to provide an ultrasonic two-dimensional phased array probe and a three-dimensional imaging method, which can solve at least one technical problem mentioned in the prior art.

[0008] One aspect of this application provides an ultrasonic two-dimensional phased array probe. The ultrasonic two-dimensional phased array probe includes an ultrasonic transmitting module and an ultrasonic receiving module. The ultrasonic transmitting module is used to transmit ultrasonic signals to an imaging medium. The ultrasonic transmitting module includes a transmitting transducer array and a transmitting circuit module connected to the transmitting transducer array. The transmitting circuit module is used to apply an excitation delay and optimize the power of the output signal. The ultrasonic receiving module is used to receive echo signals in the imaging medium. The ultrasonic receiving module includes a receiving transducer array and a receiving circuit module connected to the receiving transducer array. The receiving circuit module is used to optimize the quality of the received signal. The transmitting transducer array and the receiving transducer array are arranged in a two-dimensional orthogonal configuration.

[0009] Furthermore, the transmitting transducer array includes a row of horizontally arranged transmitting transducer elements, and the receiving transducer array includes multiple columns of vertically arranged receiving transducer elements. The transmitting transducer array is perpendicular to each column of the receiving transducer array and passes through the center of each column.

[0010] Furthermore, in the receiving transducer array, the receiving transducer array is symmetrical about the transmitting transducer array, and the number of receiving transducer array elements in each column is equal and even.

[0011] Furthermore, all transducer elements are squares of equal size, and the distance between adjacent transducer elements does not exceed half the wavelength corresponding to the ultrasonic two-dimensional phased array probe.

[0012] Furthermore, the transmitting transducer array is made of a material with a high electromechanical coupling coefficient; the receiving transducer array is made of a material with a high voltage constant.

[0013] Furthermore, the transmitting circuit module is used to maximize output power based on impedance equalization matching; the receiving circuit module is used to avoid phase distortion and suppress noise based on conjugate matching.

[0014] Another aspect of this application provides a three-dimensional imaging method. The method includes: defining a pyramid-shaped three-dimensional imaging field of view, the pyramid-shaped three-dimensional imaging field of view being determined by a lateral subtraction angle, a longitudinal subtraction angle, and an imaging depth; performing ultrasonic transmission using the ultrasonic transmitting module in the ultrasonic two-dimensional phased array probe as described above, and acquiring echo signals using the ultrasonic receiving module in the ultrasonic two-dimensional phased array probe after transmission; and performing beamforming on the echo signals after acquisition to obtain a final image.

[0015] Furthermore, the method also includes: performing three-dimensional spatial interpolation after beamforming to obtain the final image.

[0016] Furthermore, the lateral angle and the longitudinal angle are equal in size and are determined by the ratio of the width to the wavelength of the transducer element in the ultrasonic two-dimensional phased array probe.

[0017] Furthermore, the calculation method for the transverse subtended angle and the longitudinal subtended angle includes: a calculation function. exist exist The values ​​in the interval, where This represents the width of the transducer array element. Represents wavelength; find the function The first decrease to 0.707 corresponds to Value; will The value is twice the value of the transverse angle and the longitudinal angle.

[0018] Furthermore, the ultrasonic emission includes: performing multiple focused emissions at equal angular intervals within the lateral angle of the imaging field of view, wherein the number of emissions is equal to the number of array elements in the transmitting transducer array, focusing is achieved by applying excitation signals with different delays to different transmitting transducer array elements, and the focal depth is equal to the imaging depth.

[0019] Furthermore, the beamforming of the echo signal includes: for any voxel within the three-dimensional imaging field of view, calculating the back propagation time from the voxel to each receiving transducer element; determining all relevant focused emissions of the voxel, calculating the forward propagation time of each relevant focused emission, wherein the relevant focused emission is the focused emission whose focused coverage area includes the voxel; adding the forward propagation time and the back propagation time to obtain the occurrence time of the voxel's echo signal at each relevant focused emission and each receiving transducer element, and extracting the corresponding signal value according to time to achieve coherent composite.

[0020] Further, the calculation of the forward propagation time for each focused emission includes: determining the plane formed by the voxel and the emission transducer array, calculating the two-dimensional coordinates of the voxel on the plane; connecting the voxel to the focal point on the plane, calculating the ultrasonic propagation time of the line segment between the voxel and the focal point; and subtracting the ultrasonic propagation time of the line segment from the time it takes for the ultrasound to reach the focal point on the plane to obtain the forward propagation time.

[0021] The ultrasonic two-dimensional phased array probe and three-dimensional imaging method of one or more embodiments of this application can achieve the following beneficial technical effects:

[0022] (1) The phased array design expands the imaging field of view;

[0023] (2) The orthogonal configuration significantly reduces the number of array elements and the amount of data.

[0024] (3) The design of separate transmission and reception improves the signal-to-noise ratio of the echo signal;

[0025] (4) The minimum number of focusing emission times for imaging is specified to ensure the imaging frame rate;

[0026] (5) It provides an accurate echo travel time model, which simplifies the reconstruction process. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the composition of an ultrasonic two-dimensional phased array probe according to an embodiment of this application.

[0028] Figure 2 This is a flowchart illustrating a three-dimensional imaging method according to an embodiment of this application.

[0029] Figure 3 This is a schematic diagram of a pyramid-shaped three-dimensional imaging field of view according to an embodiment of this application.

[0030] Figure 4 This is a schematic diagram of two adjacent focused emission beams within the lateral section of the imaging field of view according to an embodiment of this application.

[0031] Figure 5 This is a schematic diagram illustrating the calculation of the forward propagation time of a focused emission according to one embodiment of this application. Detailed Implementation

[0032] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses consistent with some aspects of this application as detailed in the appended claims.

[0033] The ultrasonic two-dimensional phased array probe and three-dimensional imaging method of this application will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the features in the following embodiments and implementations can be combined with each other.

[0034] Figure 1 A schematic diagram illustrating the composition of an ultrasonic two-dimensional phased array probe 100 according to one embodiment of this application is shown. Figure 1 As shown, an ultrasonic two-dimensional phased array probe 100 according to one embodiment of this application includes an ultrasonic transmitting module and an ultrasonic receiving module.

[0035] The ultrasonic transmitting module is used to transmit ultrasonic signals to the imaging medium. The ultrasonic transmitting module includes a transmitting transducer array 110 and a transmitting circuit module 120 connected to the transmitting transducer array 110. The transmitting circuit module 120 is used to apply excitation delay and optimize the power of the output signal.

[0036] The ultrasound receiving module is used to receive echo signals in the imaging medium. The ultrasound receiving module includes a receiving transducer array 130 and a receiving circuit module 140 connected to the receiving transducer array 130. The receiving circuit module 140 is used to optimize the quality of the received signal.

[0037] The transmitting transducer array 110 and the receiving transducer array 130 are arranged in a two-dimensional orthogonal configuration.

[0038] In some embodiments, the transmitting transducer array 110 includes a row of transmitting transducer elements 111 arranged laterally (x-axis) (e.g., ...). Figure 1 (As shown by the black square in the image), the receiver transducer array 130 includes multiple columns of vertically (y-axis) arranged receiver transducer elements 131 (such as...). Figure 1 (As shown by the white square in the image).

[0039] In this ultrasonic two-dimensional phased array probe 100, all transducer elements are squares of equal size, and the distance between adjacent transducer elements does not exceed half the corresponding wavelength of the ultrasonic two-dimensional phased array probe 100. This design brings phased characteristics, which allows the array to have a large beam deflection angle in both the horizontal and vertical directions, thus providing a wide imaging field of view.

[0040] Optionally, the transmitting transducer array 110 is perpendicular to each column of the receiving transducer array 130 and runs through the center of each column.

[0041] Optionally, in the receiving transducer array 130, the receiving transducer array 130 is symmetrical about the transmitting transducer array 110, and the number of receiving transducer array elements 131 in each column is equal and even.

[0042] In some embodiments, the transmitting transducer array 110 and the receiving transducer array 130 are made of different materials. Optionally, the transmitting transducer array 110 is made of a material with a high electromechanical coupling coefficient, such as PZT (lead zirconate titanate)-4, PZT-8, etc.; the receiving transducer array 130 is made of a material with a high voltage constant, such as PZT-5H, PZT-7A, etc.

[0043] In some embodiments, the transmitting circuit module 120 and the receiving circuit module 140 have different electrical matching functions. The transmitting circuit module 120 can maximize output power based on impedance equalization matching. Specifically, the output impedance magnitude of the transmitting circuit module 120 is equal to the output impedance of the back-end host computer system to reduce energy reflection and maximize energy transmission. The receiving circuit module 140 can avoid phase distortion and suppress noise based on conjugate matching. Specifically, the reactance of the receiving circuit module 140 needs to cancel the reactance of the receiving transducer element 131 to avoid complex phase changes of the received signal with frequency, and the output impedance magnitude of the receiving circuit module 140 is equal to the output impedance of the back-end host computer system to optimize transmission efficiency and improve the signal-to-noise ratio.

[0044] Figure 2 A flowchart illustrating a three-dimensional imaging method according to an embodiment of this application is shown. Figure 2 As shown, a three-dimensional imaging method according to one embodiment of this application may include steps S1 to S5.

[0045] In step S1, a pyramid-shaped three-dimensional imaging field of view is defined.

[0046] Figure 3 A schematic diagram illustrating a pyramid-shaped three-dimensional imaging field of view according to an embodiment of this application is shown. Figure 3 As shown, the pyramid-shaped three-dimensional imaging field of view is determined by the horizontal subtraction angle, the vertical subtraction angle, and the imaging depth.

[0047] The transverse and longitudinal angles are equal in size and are determined by the ratio of the width to the wavelength of the transducer elements in the ultrasonic two-dimensional phased array probe 100.

[0048] The calculation methods for the horizontal and vertical subtraction angles are as follows:

[0049] Calculation function exist exist The values ​​in the interval, where Represents the width of the transducer array element. Represents wavelength;

[0050] turn up The first decrease to 0.707 corresponds to value;

[0051] Double this θ value is taken as the horizontal and vertical subtraction angles, i.e. , This indicates the horizontal and vertical angles of the opening.

[0052] Continue to refer to Figure 2 In step S2, ultrasonic transmission is performed using the ultrasonic transmission module in the ultrasonic two-dimensional phased array probe 100 described above.

[0053] Multiple focused emissions with equal angular spacing are performed within the lateral angle of the imaging field of view, wherein the number of emissions is equal to the number of array elements in the transmitting transducer array 110.

[0054] Focusing is achieved by applying excitation signals with different delays to different transmitting transducer array elements 111, and the focal depth is equal to the imaging depth of the three-dimensional imaging field of view.

[0055] Figure 4 This illustration reveals a schematic diagram of two adjacent focused emission beams within a lateral section of the imaging field of view, according to an embodiment of this application. (See attached diagram.) Figure 4 As shown, assuming the number of elements in the transmitting transducer array 110 is... So, in total, it is necessary to conduct Sub-focused emission, with each focusing depth exactly equal to the imaging depth. Then the angular interval between any two adjacent focusing beam centerlines... equal ,Right now , Indicates the lateral angle.

[0056] Continue to refer to Figure 2 In step S3, after the transmission is completed, the echo signal is acquired using the ultrasonic receiving module in the ultrasonic two-dimensional phased array probe 100 described above.

[0057] In step S4, after the acquisition is completed, beamforming is performed on the echo signal.

[0058] In some embodiments, step S4, which involves beamforming the echo signal, may further include steps S41 to S43.

[0059] In step S41, for any voxel within the three-dimensional imaging field of view, the back propagation time from the voxel to each receiving transducer element 131 is calculated.

[0060] Assuming the voxel and the first The spatial coordinates of each receiving transducer element 131 are as follows: and Then, the time of backward propagation for:

[0061] (1)

[0062] in, The sound velocity constant represents the imaging medium.

[0063] In step S42, all relevant focused emissions of the voxel are determined, and the forward propagation time of each relevant focused emission is calculated.

[0064] Among them, focused emission refers to focused emission within the focused coverage area of ​​the voxel.

[0065] Figure 5 A schematic diagram illustrating the calculation of the forward propagation time of a focused emission according to an embodiment of this application is shown below. Figure 5 This will illustrate how to calculate the forward propagation time for each focused emission.

[0066] In some embodiments, the calculation of the forward propagation time for each focused emission in step S42 may include steps S421 to S423.

[0067] like Figure 5 As shown, in step S421, the plane formed by the voxel and the emission transducer array 110 is determined, and the two-dimensional coordinates of the voxel on the plane are calculated.

[0068] The plane is determined by connecting the two ends of the transmitting transducer array 110 to the voxel, and then the two-dimensional coordinates of the voxel on the plane are determined.

[0069] In step S422, the voxel is connected to the focal point on the plane, and the ultrasonic propagation time of the line segment between the voxel and the focal point is calculated.

[0070] In step S423, the forward propagation time is obtained by subtracting the ultrasonic propagation time of the line segment from the time it takes for the ultrasound to reach the focal point on the plane.

[0071] Forward propagation time can be expressed as:

[0072] (2)

[0073] in, Representing the Subfocus launch The time it takes for the ultrasound to reach the emission focal point on that plane. and These are the two-dimensional coordinates of the voxel and the focus on the plane, respectively. Since the wavefront emitted by the linear array is symmetrical about the array line, regardless of the voxel's position, it always has... ,in, Representing the The deflection angle of the secondary focused launch.

[0074] In step S43, the forward propagation time and the backward propagation time are added together to obtain the echo signal of the voxel at the occurrence time of each focused emission and each receiving transducer element 131. The corresponding signal value is extracted according to the time to achieve coherent recombination.

[0075] This process can be expressed as:

[0076] (3)

[0077] in, Represented in voxels Pixel value at that location, Representing the After the secondary focused transmission, the receiving transducer array 130 is the first The echo signal of each array element.

[0078] For a voxel Not every focused launch can capture that voxel. According to voxels Depending on its location, the focused emission can scan the voxel. The number of times is different. For example Figure 4 As shown, when voxels When approaching the upper region of the 3D imaging field of view, the voxel is scanned. The number of times will be more; while when voxels When approaching the lower region of the 3D imaging field of view, the voxel is scanned. The number of times will be less. And regarding focused emission, the focused coverage area includes the voxel. The focused emission. Therefore, in the above formula (3), Representative scanned voxels The set of focused emission sequences, i.e., the voxels scanned. The number of times the focused launch is performed.

[0079] Return to reference Figure 2 In step S5, after beamforming, three-dimensional spatial interpolation is performed to obtain the final image.

[0080] because The computational load is relatively large; therefore, in some embodiments, voxels can be used. Achieving relatively sparseness, sufficient to meet basic resolution, thereby reducing... The calculation is then performed. Then, based on actual needs, the final image can be obtained through three-dimensional spatial interpolation, thereby further improving the resolution and meeting the requirements for image clarity.

[0081] Of course, it is understood that step S5 of this application can be omitted under certain conditions. For example, in other embodiments, more voxels can be selected. To increase The final image is obtained by calculation, thus eliminating the need for the interpolation process in step S5.

[0082] The ultrasonic two-dimensional phased array probe 100 and three-dimensional imaging method according to one or more embodiments of this application can achieve the following beneficial technical effects:

[0083] (1) The phased array design expands the imaging field of view;

[0084] (2) The orthogonal configuration significantly reduces the number of array elements and the amount of data.

[0085] (3) The design of separate transmission and reception improves the signal-to-noise ratio of the echo signal;

[0086] (4) The minimum number of focusing emission times for imaging is specified to ensure the imaging frame rate;

[0087] (5) It provides an accurate echo travel time model, which simplifies the reconstruction process.

[0088] The ultrasonic two-dimensional phased array probe and three-dimensional imaging method provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the ultrasonic two-dimensional phased array probe and three-dimensional imaging method of this application. The descriptions of the embodiments above are only for helping to understand the core ideas of this application and are not intended to limit this application. It should be noted that for those skilled in the art, several improvements and modifications can be made to this application without departing from the spirit and principles of this application, and these improvements and modifications should all fall within the protection scope of the appended claims.

Claims

1. A three-dimensional imaging method, characterized in that, include: A pyramid-shaped three-dimensional imaging field of view is defined, wherein the pyramid-shaped three-dimensional imaging field of view is determined by the lateral subtraction angle, the longitudinal subtraction angle, and the imaging depth; Ultrasonic transmission is performed using the ultrasonic transmitting module in a two-dimensional phased array ultrasonic probe. After transmission, the echo signal is acquired using the ultrasonic receiving module in the same probe. The ultrasonic transmitting module includes a transmitting transducer array and a transmitting circuit module connected to the transmitting transducer array. The transmitting circuit module is used to apply an excitation delay and optimize the power of the output signal. The ultrasonic receiving module includes a receiving transducer array and a receiving circuit module connected to the receiving transducer array. The receiving circuit module is used to optimize the quality of the received signal. The transmitting transducer array and the receiving transducer array are arranged in a two-dimensional orthogonal configuration. After acquisition, beamforming is performed on the echo signals to obtain the final image. The beamforming of the echo signal includes: for any voxel within the three-dimensional imaging field of view, calculating the back propagation time from the voxel to each receiving transducer element; determining all relevant focused emissions of the voxel, calculating the forward propagation time of each relevant focused emission, wherein the relevant focused emission is the focused emission whose focused coverage area includes the voxel; adding the forward propagation time and the back propagation time to obtain the occurrence time of the voxel's echo signal at each relevant focused emission and each receiving transducer element, and extracting the corresponding signal value according to time to achieve coherent composite.

2. The three-dimensional imaging method as described in claim 1, characterized in that, Also includes: After beamforming, three-dimensional spatial interpolation is performed to obtain the final image.

3. The three-dimensional imaging method as described in claim 1, characterized in that, The lateral and longitudinal angles are equal in size and are determined by the ratio of the width to the wavelength of the transducer elements in the ultrasonic two-dimensional phased array probe.

4. The three-dimensional imaging method as described in claim 3, characterized in that, The calculation methods for the lateral subtraction angle and the longitudinal subtraction angle include: Calculation function exist exist The values ​​in the interval, where This represents the width of the transducer array element. Represents wavelength; Find the function The first decrease to 0.707 corresponds to value; This The value is twice the value of the transverse angle and the longitudinal angle.

5. The three-dimensional imaging method as described in claim 1, characterized in that, The ultrasonic emission includes: Multiple focused emissions with equal angular intervals are performed within the lateral angle of the imaging field of view, wherein the number of emissions is equal to the number of array elements in the transmitting transducer array, and focusing is achieved by applying excitation signals with different delays to different transmitting transducer array elements, and the focal depth is equal to the imaging depth.

6. The three-dimensional imaging method as described in claim 1, characterized in that, The calculation of the forward propagation time for each focused emission includes: Determine the plane formed by the voxel and the transmitting transducer array, and calculate the two-dimensional coordinates of the voxel on the plane; Connect the voxel to the focal point on the plane and calculate the ultrasonic propagation time of the line segment between the voxel and the focal point; The forward propagation time is obtained by subtracting the time it takes for the ultrasound to reach the focal point on the plane from the ultrasound propagation time of the line segment.

7. The three-dimensional imaging method as described in claim 1, characterized in that, The transmitting transducer array includes a row of horizontally arranged transmitting transducer elements, and the receiving transducer array includes multiple columns of vertically arranged receiving transducer elements. The transmitting transducer array is perpendicular to each column of the receiving transducer array and passes through the center of each column.

8. The three-dimensional imaging method as described in claim 7, characterized in that, In the receiving transducer array, the receiving transducer array is symmetrical about the transmitting transducer array, and the number of receiving transducer elements in each column is equal and even.

9. The three-dimensional imaging method as described in claim 7, characterized in that, All transducer elements are squares of equal size, and the distance between adjacent transducer elements does not exceed half the wavelength of the corresponding wavelength of the ultrasonic two-dimensional phased array probe.

10. The three-dimensional imaging method as described in claim 1, characterized in that, The transmitting transducer array is made of a material with a high electromechanical coupling coefficient; the receiving transducer array is made of a material with a high voltage constant.

11. The three-dimensional imaging method as described in claim 1, characterized in that, The transmitting circuit module is used to maximize output power based on impedance equalization matching; the receiving circuit module is used to avoid phase distortion and suppress noise based on conjugate matching.

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