Patent Application
20220071594
This invention relates to two dimensional transducers arrays for ultrasound imaging. This invention also relates to two dimensional arrays suitable for formation of two dimensional (2D) and/or three dimensional (3D) ultrasound images. This invention further relates to two dimensional arrays suitable for real-time 2D and/or 3D ultrasound imaging. This invention further relates to bowtie transducer arrays and rectangular transducer arrays suitable for real-time 2D and/or 3D ultrasound imaging.
Ultrasound probes utilizing 2D array transducers enable reliable real-time 3D imaging. Since their development nearly 30 years ago, rapid advancements in sparse array design and subsequent fully-sampled 2D arrays have occurred. Fully-sampled 2D array transducers are most commonly used in obstetrics, and cardiology, with increasing application in radiology.
The majority of fully-sampled arrays operate in the 2-7 MHz range which is frequently used in obstetrics and cardiology. Recently, Philips® has developed the XL14-3 array for imaging of superficial targets in humans such as the carotid artery with high spatial resolution and excellent contrast to noise ratio. These arrays have a footprint on the order of 1-4 cm2 and have tens of thousands of elements enabling both fine focus in azimuth as well as excellent slice thickness uniformity due to electronic focusing in elevation [1].
Startup companies such as Butterfly Networks and Exo Imaging use capacitive micromachined ultrasonic transducers (cMUTs) and piezoelectric micromachined ultrasonic transducers (pMUTs) for imaging systems capable of imaging a wide range of targets. These systems use ASICs to miniaturize and provide electronics in a small form factor. These ASICs are placed in close proximity to the 2D array to simplify cabling and maximize signal-to-noise ratio. ASICs funnel signals from thousands of elements to a more manageable number of system receive channels [1].
Within these ASICs, sub-aperture or micro-beamforming is performed on clusters of elements. Significant academic and industrial research has investigated ASIC designs in which all transmit and receive circuitry fit within the area of an ultrasound element [1-5]. This may lead to compromises in array performance such as lowering transmit voltages and using unipolar pulsers. It may also frequently require relaxing the noise performance of receive amplifiers to greatly reduce the dissipated current in the probe handle.
The main challenge with this architecture is the fact that the transmit and receive circuitry for a particular element may have to sit immediately behind the transducer and may have therefore to occupy a limited area dictated by the 2D array element pitch. This may require the ASIC designer to scale down often complex circuitry to a simplified form with a small number of transistor devices that can fit in the limited available design area.
The problem may especially be acute when both low voltage (LV) and high voltage (HV) devices are used because HV devices may typically be 10× larger than equivalent functionality LV devices due to the requirements for voltage standoff for isolation. The compromise may require the HV circuitry to be reduced in functionality and/or transmit voltage, while the LV circuitry may require sacrifice in noise performance due to the limitation on the size of the input pair which may determine the thermal and 1/f noise of the receive circuit. In addition, HV fabrication processes typically lag LV in process node integration which may mean that the digital circuitry will not be optimized and will also consume significant area behind the elements, further compromising performance. Substrate crosstalk between transmit and receive circuits may also present a challenge with highly integrated systems.
Point-of-care ultrasound is playing an increasingly important role for patient management in the intensive care unit (ICU). In the early 1990s, transthoracic echocardiography was shown to improve patient outcomes with cardiac injury. In the ICU, the most common indications and applications of TTE are the hypotensive patient, patients with chest pain, cardiac trauma, cardiac arrest, mechanically ventilated patients, and post-cardiac surgery patients. Today, system miniaturization, innovations in transducers, and development of training programs have led to increasing use of ultrasound to expedite evaluation, diagnosis, and treatment at the bedside.
3D ultrasound imaging strives to overcome many of the limitations of 2D imaging. Specifically, the diagnostician no longer must mentally integrate a series of 2D images into a 3D interpretation of the anatomy. With 2D imaging, it is not feasible to fine the same image plane on a consistent basis over time as is needed for serial monitoring. 3D ultrasound has greater accuracy and less variability when performing volume measurements. Assumptions normally made to calculate volumes from 2D images no longer must be made with 3D images. 3D imaging is more reproducible than 2D ultrasound make it more suitable for monitoring purposes.
3D ultrasound systems may have different levels of complexity ranging from the use of spatial locators integrated with 2D imaging systems to fully-sampled 2D arrays with true 3D beamforming and steering. The first clinical RT3D scanners employed sparse array technology which allowed for simpler transducer fabrication and system development. A disadvantage of such systems may be the increased sidelobe levels and clutter in the image. Developing fully-sampled 2D arrays having several thousands of elements may technologically be difficult and expensive. Application-specific integrated circuits (ASICs) in the probe handle may funnel the signals from thousands of elements into 64-192 signals for further beamforming in the system. ASICs may also have several disadvantages including a noise-power tradeoff, heat dissipation, and sacrifices in hardware performance.
In recent years, many researchers have explored the use of row-column or top-orthogonal-to-bottom (TOBE) arrays as a way of simplifying transducer design. However, due to the elongated elements of a row-column array, the row-column array may be amenable to steering and focusing at large angles.
The following documents are related art for the background of this disclosure. One digit or two digit numbers in the box brackets before each reference, correspond to the numbers in the box brackets, and that may be referenced in other parts of this disclosure.
The contents of each of these documents are incorporated herein in their entirety by reference.
This invention relates to an ultrasound imaging system. This invention relates to two dimensional transducers arrays for ultrasound imaging. This invention also relates to two dimensional arrays suitable for formation of two-dimensional (2D) and/or three-dimensional (3D) ultrasound images. This invention further relates to two dimensional arrays suitable for real-time 2D and/or 3D ultrasound imaging. This invention further relates to bowtie transducer arrays and rectangular transducer arrays suitable for real-time 2D and/or 3D ultrasound imaging.
In one example, the ultrasound imaging system may comprise at least one two-dimensional (2D) transducer array.
In one example, the ultrasound imaging system may be configured to form at least one two-dimensional (2D) ultrasound image of a target and/or at least one three-dimensional (3D) ultrasound image of a target.
In one example, the ultrasound imaging system may be configured to form at least one two-dimensional (2D) ultrasound image of a target in real time and/or at least one three-dimensional (3D) ultrasound image of a target in real-time.
In one example, the at least one 2D transducer array may comprise at least two transducer elements. Each transducer element may be configured to operate in only transmitter mode or in only receiver mode.
In one example, the at least one 2D transducer array may comprise at least one bowtie transducer array.
In one example, the at least one 2D transducer array may comprise two bowtie transducer arrays arranged to be orthogonal to each other.
In one example, the at least one 2D transducer array may comprise two bowtie transducer arrays arranged to be orthogonal to each other. Each bowtie transducer array may comprise at least two transducer elements. The at least two transducer elements of the one of the bowtie transducer arrays may be configured to operate in only transmitter mode. The at least two transducer elements of the other bowtie transducer array may be configured to operate in only receiver mode.
In one example, the at least one 2D transducer array may comprise two bowtie transducer arrays arranged to be orthogonal to each other. Each bowtie transducer array may comprise at least two transducer elements. The at least two transducer elements of the one of the bowtie transducer arrays may be configured to operate in only the transmitter mode. The at least two transducer elements of the other bowtie transducer array may be configured to operate in only receiver mode. Apexes of the at least two bowtie transducer arrays may meet in the center of the 2D transducer array.
In one example, the 2D ultrasound transducer array may comprise at least three transducer elements. The at least one transducer element of the at least three transducer elements may not be sampled.
The ultrasound imaging system of any of the preceding claims or the following claims, wherein the ultrasound imaging system is further configured to apply an inverse filtering to achieve an ultrasound image quality closer to a fully-sampled array.
The ultrasound imaging system of any of the preceding claims or the following claims, wherein the ultrasound imaging system may be a point-of-care real-time three-dimensional ultrasound system that may comprise a sparse transducer array, a beamforming system, and/or a signal processing system of RF data.
In one example, the transducer elements configured to operate only in the transmitter mode and/or the transducer elements configured to operate only in the transmitter mode may be bundled to one system channel.
In one example, the transducer elements may be configured such that fine delays in the transmitter mode and/or the receiver mode combined with coarser delays at a system level to provide beamforming equivalent to an ultrasound imaging system that may comprise a conventional delay-and-sum beamforming system.
In one example, the ultrasound imaging system may be configured to perform an inverse filtering operation in a frequency domain to compensate for a low magnitude response near zero frequency.
In one example, the ultrasound imaging system may comprise a bowtie transducer array. The ultrasound imaging system may be configured to perform an inverse filtering operation in the frequency domain to compensate for a low magnitude response near zero frequency.
In one example, the ultrasound imaging system may be configured to apply an inverse filter. In this example, compensation magnitudes may be limited to a maximum value varying in the range of 5 to 10 to minimize noise when the magnitude of ATR,BT goes to zero, where ATR,BT is the normalized k-space response of a bowtie array.
In one example, the ultrasound imaging system may be configured such that inverse filters may be formed by taking the 3D Fourier Transform of the RF volume data to from a single point target located on axis. The inverse filtering operation may be applied in the frequency domain by first performing a 3D Fourier Transform on the RF volume data from the transducer array. Multiplying the result with the inverse filter, and finally applying an inverse 3D Fourier Transform to this result may form a filtered 3D RF dataset.
In one example, the ultrasound imaging system may be configured such that inverse filters may be formed by taking the 3D Fourier Transform of the RF volume data to form a single point target located on axis. The inverse filtering operation may be applied in the frequency domain by first performing a 3D Fourier Transform on the RF volume data from the transducer array. Multiplying the result with the inverse filter, then applying an inverse 3D Fourier Transform to this result may form a filtered 3D RF dataset. Applying envelope detection and logarithmic compression to the 3D RF dataset may then applied.
In one example, the 2D transducer array may be a rectangular boundary array (RBA). The RBA transducer array may comprise a two parallel transducer arrays operating in only transmitter mode focusing the elevation direction. The RBA transducer array may further comprise a two parallel transducer arrays operating in only receiver mode focusing azimuth direction.
In one example, the 2D transducer array may be a rectangular boundary array (RBA). The RBA transducer array may comprise an N×N 2D array. Said array may comprise only 4N-4 elements. Half of said arrays may be configured to operate in only transmitter mode. The other half may be configured to operate in only receiver mode.
In one example, the ultrasound imaging system may be configured to apply a Barker code to increase a low signal-to-noise ratio (SNR).
In one example, the ultrasound imaging system may be configured to decode a Barker code by applying a mismatched filter.
In one example, the ultrasound imaging system may be configured to apply apodization to reduce effects of a high sidelobe level and/or a clutter level of a point spread function.
In one example, the RBA may have more than one rows and/or columns of transducer elements.
In one example, the RBA may have more than one rows and/or columns of transducer elements. Each additional array rows and/or columns may have additional redundancy to improve uniformity.
In one example, the RBA may be arranged as a stairstep like pattern.
In one example, each transducer element of the RBA may have a rectangular front face and may have its own defocusing lens.
In one example, the RBA may have a defocusing lens. The defocusing lens may be a convex defocusing lens.
In one example, the RBA may have a defocusing lens. The defocusing lens may be a concave defocusing lens.
In one example, the RBA may have a defocusing lens. The defocusing lens may have a wedge such that ultrasound energy is steered more toward a center of the array and image, or such that ultrasound energy is steered away from the center of the array.
In one example, all of the transducer elements of the transducer array may be configured to be operated in only transmitter mode or in only receiver mode. In another example, one or more of the transducer elements of the transducer array may be configured to be operated in only transmitter mode and one or more of the transducer elements of the transducer array may be configured to be operated in only receiver mode.
In one example, the ultrasound imaging system may comprise a bowtie array. The transducer elements may be operated in only transmitter mode, using ASICs which may be manufactured using a high voltage ASIC fabrication process with capability greater than above 5V. The transducer elements operated in only the receiver mode may be interfaced using ASICs manufactured using a low voltage ASIC fabrication process with capability less than about 5V.
In one example, the ultrasound imaging system may comprise a bowtie array. The transducer elements operated in only the receiver mode may be implemented using a low voltage multiplexer.
In one example, the ultrasound imaging system may comprise a bowtie array. The transducer elements may be operated in only the receiver mode, which may be implemented using a micro beam-former.
Any combination of above embodiments are within the scope of this disclosure.
Various aspects of the present disclosure are also addressed by the following paragraphs and in the noted combinations:
a plurality of elements disposed in a plurality of columns and in a plurality of rows;
a first group of said plurality of elements disposed in opposing relation to a second group of said plurality of elements;
wherein a number of elements in each column of each of said first group and said second group is reduced proceeding in a direction of a central portion of said transducer array;
wherein each of said first group and said second group comprises a first side, a second side, and a third side, wherein said second and third sides of each of said first group and said second group extend from opposite ends of a corresponding said first side and converge toward one another proceeding in a direction of said central portion of said transducer array, wherein said first side of said first group is disposed oppositely of said first side of said second group; and
wherein each said element of each of said first group and said second group is a configured to operate in a first common mode, wherein said first common mode is only one of transmit or receive.
a third group of said plurality of elements disposed in opposing relation to a fourth group of said plurality of elements;
wherein a number of elements in each row of each of said third group and said fourth group is reduced proceeding in a direction of said central portion of said transducer array;
wherein each of said third group and said fourth group comprises a first side, a second side, and a third side, wherein said second and third sides of each of said third group and said fourth group extend from opposite ends of a corresponding said first side and converge toward one another proceeding in a direction of said central portion of said transducer array, wherein said first side of said third group is disposed oppositely of said first side of said fourth group.
wherein said single element of said first group is disposed in an adjacent column and in an adjacent row to said single element of said second group; and
wherein said single element of said third group is disposed in an adjacent column and in an adjacent row to said single element of said fourth group.
a first group of multiple said elements, wherein said first group includes at least two adjacent columns, and wherein a first side of said transducer array comprises said first group;
a second group of multiple said elements, wherein said second group includes at least two adjacent columns, and wherein a second side of said transducer array that is opposite said first side comprises said second group;
a third group of multiple said elements, wherein said third group includes at least two adjacent rows, and wherein a third side of said transducer array comprises said third group;
a fourth group of multiple said elements, wherein said fourth group includes at least two adjacent rows, and wherein a fourth side of said transducer array that is opposite said third side comprises said fourth group;
wherein said third side and said fourth side each extend between said first side and said second side;
wherein each said element of each of said first group and said second group is a configured to operate in a first common mode, wherein said first common mode is only one of transmit or receive; and
wherein each said element of each of said third group and said fourth group is a configured to operate in a second common mode, wherein said second common mode is only the other of transmit or receive.
wherein a number of said elements in a first column of said first group is greater than a number of said elements in an adjacent column of said first group, wherein said first column of said first group is on a perimeter of said transducer array;
wherein a number of said elements in a second column of said second group is greater than a number of said elements in an adjacent column of said second group, wherein said second column of said second group is on said perimeter of said transducer array;
wherein a number of said elements in a first row of said third group is greater than a number of said elements in an adjacent row of said third group, wherein said first row of said third group is on said perimeter of said transducer array; and
wherein a number of said elements in a second row of said fourth group is greater than a number of said elements in an adjacent row of said fourth group, wherein said second row of said fourth group is on said perimeter of said transducer array.
wherein there are two more said elements in said first column of said first group than said adjacent column of said first group;
wherein there are two more said elements in said second column of said second group than said adjacent column of said second group;
wherein there are two more said elements in said first row of said third group than said adjacent row of said third group; and
wherein there are two more said elements in said second row of said fourth group than said adjacent row of said fourth group.
a first group of a plurality of said elements, wherein a first side of said transducer array comprises said first group;
a second group of a plurality of said elements, wherein a second side of said transducer array that is opposite said first side comprises said second group, wherein said elements are disposed in a common first orientation for each of said first group and said second group, and wherein said first group and said second group include a common number of said elements;
a third group of a plurality of said elements, wherein a third side of said transducer array comprises said third group;
a fourth group of a plurality of said elements, wherein a fourth side of said transducer array that is opposite said third side comprises said fourth group, wherein said elements are in a common second orientation for each of said third group and said fourth group, wherein said third group and said fourth group include a common number of said elements, and wherein said first orientation is different from said second orientation;
wherein said third side and said fourth side each extend between said first side and said second side;
wherein each said element of each of said first group and said second group is a configured to operate in a first common mode, wherein said first common mode is only one of transmit or receive; and
wherein each said element of each of said third group and said fourth group is a configured to operate in a second common mode, wherein said second common mode is only the other of transmit or receive.
These, as well as other components, steps, features, objects, benefits, and advantages, will now become clear from a review of the following detailed description of illustrative examples, the accompanying drawings, and the claims.
For purposes of summarizing the disclosure, certain aspects, advantages, and novel feature are discussed herein. It is to be understood that not necessarily all such aspects, advantages, or features will be embodied in any particular embodiment of the disclosure, and an artisan would recognize from the disclosure herein a myriad of combinations of such aspects, advantages, or features.
The drawings are of illustrative embodiments. They do not illustrate all embodiments. Other embodiments may be used in addition or instead. Details that may be apparent or unnecessary may be omitted to save space or for more effective illustration. Some embodiments may be practiced with additional components or steps and/or without all of the components or steps that are illustrated. When the same numeral appears in different drawings, it refers to the same or like components or steps. The entire contents of these patent applications are incorporated herein by reference. The patent application file contains these and additional drawings and photos executed in color. Copies of this patent application file with color drawings and photos will be provided by the United States Patent and Trademark Office upon request and payment of the necessary fee.
Illustrative examples are now described. Other examples may be used in addition or instead. Details that may be apparent or unnecessary may be omitted to save space or for a more effective presentation. Some examples may be practiced with additional components or steps and/or without all of the components or steps that are described.
This disclosure relates to two dimensional transducers arrays for ultrasound imaging. This disclosure also relates to two dimensional arrays suitable for formation of two-dimensional (2D) and/or three-dimensional (3D) ultrasound images. This disclosure further relates to two dimensional arrays suitable for real-time 2D and/or 3D ultrasound imaging. This disclosure further relates to bowtie transducer arrays and rectangular transducer arrays suitable for real-time 2D and/or 3D ultrasound imaging.
In one example, this disclosure relates to a 2D array design to alleviate the ASIC design challenges and compromises disclosed above. This 2D array design may use all available elements but any given element may be used in transmit only or receive only. Both transmit and receive apertures, which have the shape of a bowtie, may be arranged orthogonal to each other. The interface electronics to drive and receive signals for the transmit and receive apertures respectively may be fabricated separately using separate HV and LV ASICs. The apertures may then be tiled together. The performance of the bowtie array may be analyzed through a series of Field II simulations and compared to a fully-sampled array in terms of resolution, sidelobe levels, and contrast. An inverse filtering approach may be applied to achieve image quality closer to the fully-sampled array.
This disclosure also relates to a point-of-care RT3D ultrasound system that comprises sparse array design, beamforming, and/or signal processing of RF data.
In one example, the ultrasound imaging system may comprise at least one two dimensional (2D) transducer array.
In one example, the ultrasound imaging system may be configured to form at least one two dimensional (2D) ultrasound image of a target and/or at least one three dimensional (3D) ultrasound image of a target.
In one example, the ultrasound imaging system may be configured to form at least one two-dimensional (2D) ultrasound image of a target in real time and/or at least one three-dimensional (3D) ultrasound image of a target in real-time.
In one example, the at least one 2D transducer array may comprise at least two transducer elements. Each transducer element may be configured to operate in only transmitter mode or in only receiver mode.
In one example, the at least one 2D transducer array may comprise at least one bowtie transducer array.
In one example, the at least one 2D transducer array may comprise two bowtie transducer arrays arranged to be orthogonal to each other.
In one example, the at least one 2D transducer array may comprise two bowtie transducer arrays arranged to be orthogonal to each other. Each bowtie transducer array may comprise at least two transducer elements. The at least two transducer elements of the one of the bowtie transducer arrays may be configured to operate in only transmitter mode. The at least two transducer elements of the other bowtie transducer array may be configured to operate in only receiver mode.
In one example, the at least one 2D transducer array may comprise two bowtie transducer arrays arranged to be orthogonal to each other. Each bowtie transducer array may comprise at least two transducer elements. The at least two transducer elements of the one of the bowtie transducer arrays may be configured to operate in only the transmitter mode. The at least two transducer elements of the other bowtie transducer array may be configured to operate in only receiver mode. Apexes of the at least two bowtie transducer arrays may meet in the center of the 2D transducer array.
In one example, the 2D ultrasound transducer array may comprise at least three transducer elements. The at least one transducer element of the at least three transducer elements may not be sampled.
In one example, the ultrasound imaging system is further configured to apply an inverse filtering to achieve an ultrasound image quality closer to a fully-sampled array.
In one example, the ultrasound imaging system may be a point-of-care real-time three-dimensional ultrasound system that may comprise a sparse transducer array, a beamforming system, and/or a signal processing system of RF data.
In one example, the transducer elements configured to operate only in the transmitter mode and/or the transducer elements configured to operate only in the transmitter mode may be bundled to one system channel.
In one example, the transducer elements may be configured such that fine delays in the transmitter mode and/or the receiver mode combined with coarser delays at a system level to provide beamforming equivalent to an ultrasound imaging system that may comprise a conventional delay-and-sum beamforming system.
In one example, the ultrasound imaging system may be configured to perform an inverse filtering operation in a frequency domain to compensate for a low magnitude response near zero frequency.
In one example, the ultrasound imaging system may comprise a bowtie transducer array. The ultrasound imaging system may be configured to perform an inverse filtering operation in the frequency domain to compensate for a low magnitude response near zero frequency.
In one example, the ultrasound imaging system may be configured to apply an inverse filter. In this example, compensation magnitudes may be limited to a maximum value varying in the range of 5 to 10 to minimize noise when the magnitude of ATR,BT (the normalized k-space response of the bowtie array) goes to zero.
In one example, the ultrasound imaging system may be configured such that inverse filters may be formed by taking the 3D Fourier Transform of the RF volume data to from a single point target located on axis. The inverse filtering operation may be applied in the frequency domain by first performing a 3D Fourier Transform on the RF volume data from the transducer array. Multiplying the result with the inverse filter, and finally applying an inverse 3D Fourier Transform to this result may form a filtered 3D RF dataset.
In one example, the ultrasound imaging system may be configured such that inverse filters may be formed by taking the 3D Fourier Transform of the RF volume data to from a single point target located on axis. The inverse filtering operation may be applied in the frequency domain by first performing a 3D Fourier Transform on the RF volume data from the transducer array. Multiplying the result with the inverse filter, then applying an inverse 3D Fourier Transform to this result may form a filtered 3D RF dataset. Applying envelope detection and logarithmic compression to the 3D RF dataset may then applied.
In one example, the 2D transducer array may be a rectangular boundary array (RBA). The RBA transducer array may comprise a two parallel transducer arrays operating in only transmitter mode focusing the elevation direction. The RBA transducer array may further comprise a two parallel transducer arrays operating in only receiver mode focusing the azimuth direction.
In one example, the 2D transducer array may be a rectangular boundary array (RBA). The RBA transducer array may comprise an N×N 2D array. Said array may comprise only 4N-4 elements. Half of said arrays may be configured to operate in only transmitter mode. The other half may be configured to operate in only receiver mode.
In one example, the ultrasound imaging system may be configured to apply a Barker or other (e.g., Golay) code to increase a low signal-to-noise ratio (SNR).
In one example, the ultrasound imaging system may be configured to decode a Barker code by applying a mismatched filter.
In one example, the ultrasound imaging system may be configured to apply apodization to reduce effects of a high sidelobe level and/or a clutter level of a point spread function.
In one example, the RBA may have more than one rows and/or columns of transducer elements.
In one example, the RBA may have more than one rows and/or columns of transducer elements. Each additional array rows and/or columns may have additional redundancy to improve uniformity.
In one example, the RBA may be arranged as a stairstep like pattern.
In one example, each transducer element of the RBA may have a rectangular front face and have its own defocusing lens.
In one example, the RBA may have a defocusing lens. The defocusing lens may be a convex defocusing lens.
In one example, the RBA may have a defocusing lens. The defocusing lens may be a concave defocusing lens.
In one example, the RBA may have a defocusing lens. The defocusing lens may have a wedge such that ultrasound energy is steered more toward a center of the array and image or such that ultrasound energy is steered away from the center of the array.
In one example, each of the transducer elements of the transducer array may be configured to be operated in only transmitter mode or in only receiver mode, with the transducer array including at least one transducer element configured to operate in only transmitter mode and including at least one transducer element configured to operate in only receiver mode.
In one example, the ultrasound imaging system may comprise a bowtie array. The transducer elements may be operated in only transmitter mode, the interface electronics for which may be manufactured using a high voltage ASIC fabrication process with capability greater than above 5V. The transducer elements operated in only the receiver mode may be interfaced to interface electronics manufactured using a low voltage ASIC fabrication process with capability less than about 5V.
In one example, the ultrasound imaging system may comprise a bowtie array. The transducer elements operated in only the receiver mode may be interfaced to electronics which are implemented using a low voltage multiplexer.
In one example, the ultrasound imaging system may comprise a bowtie array. The transducer elements may be operated in only the receiver mode, which may be interfaced to electronics which are implemented using a micro beam-former comprising low voltage fabricated ASICs.
Any combination of above embodiments are within the scope of this disclosure.
For illustrative purposes, a bowtie array layout of a 16×162D array 10 is shown in
The ultrasound transducer array 10 of
Each of the groups 40, 50, 60, and 70, include a plurality of the noted elements 30. Each element 30 of both the first group 40 and the second group 50 may be configured to operate only in a first common mode that is one of transmit or receive, while each element 30 of both the third group 60 and the fourth group 70 may be configured to operate only in a second common mode that is the other of transmit or receive. That is, each of the elements 30 of both the first group 40 and the second group 50 may be configured only to operate as a transmit element, while each of the elements 30 of both the third group 60 and the fourth group 70 may be configured only to operate as a receive element. Alternatively, each of the elements 30 of both the first group 40 and the second group 50 may be configured only to operate as a receive element, while each of the elements 30 of both the third group 60 and the fourth group 70 may be configured only to operate as a transmit element.
Each of the elements 30 in each of the first group 40, second group 50, third group 60, and fourth group 70 may include a front surface through which the corresponding transmit or receive function is provided (this front surface being shown in
With reference to both
The second group 50 may be characterized as being at least generally triangularly-shaped, with a first side 52, a second side 54, and a third side 56. The second or the right side 16 of the ultrasound transducer array 10 may include the first side 52 of the second group 50. The second side 54 and the third side 56 of the second group 50 may converge toward one another proceeding from the first side 52 and in a direction of a central location of the ultrasound transducer array 10, and may converge to a single element 58 of the second group 50.
The third group 60 may be characterized as being at least generally triangularly-shaped, with a first side 62, a second side 64, and a third side 66. The third or the upper side 18 of the ultrasound transducer array 10 may include the first side 62 of the third group 60. The second side 64 and the third side 66 of the third group 60 may converge toward one another proceeding from the first side 62 and in a direction of a central location of the ultrasound transducer array 10, and may converge to a single element 68 of the third group 60.
The fourth group 70 may be characterized as being at least generally triangularly-shaped, with a first side 72, a second side 74, and a third side 76. The fourth or the lower side 20 of the ultrasound transducer array 10 may include the first side 72 of the fourth group 70. The second side 74 and the third side 76 of the fourth group 70 may converge toward one another proceeding from the first side 72 and in a direction of a central location of the ultrasound transducer array 10, and may converge to a single element 78 of the fourth group 70. A center of the ultrasound transducer array 10 may correspond with where the elements 48, 58, 68, and 78 meet or adjoin one another.
The frequency domain or k-space response of an ultrasound imaging system, ATR, may be estimated by the convolution of spatially scaled and reversed representations of the transmit and receive aperture weighting functions indicated by AT and AR respectively:
A
TR(fx,fy)=AT(fx,fy)*AR(fx,fy) Equation (1)
In Equation 1, fx and fy are the azimuthal and elevational spatial frequencies respectively, and the asterisk indicates two-dimensional (2-D) convolution. In one example, this may give the results shown in
To compensate for this, we perform an inverse filtering operation in the frequency domain. The inverse filter Q(fx,fy) is calculated as follows:
In Equation 2, ATR,FS is the normalized k-space response of a fully-sampled array and ATR,BT is the normalized k-space response of the bowtie array. A limitation of inverse filters may be the tendency to amplify noise when the magnitude of ATR,BT goes to zero. To minimize this in practice, compensation magnitudes may be limited to a maximum value in the range of 5 to 10.
Simulations of a 64×643 MHz bowtie array and a 64×64 fully-sampled array were carried out using Field II Pro. Using a sound speed of 1540 m/s, the element pitch was equal to about 257 μm, or one-half wavelength. Single point targets located on axis (about 0°, about 0°, about 60 mm) and off-axis (about 40°, about 40°, about 60 mm). Beamwidths at about −6, about −20, and about −40 dB were measured. Simulations involving multiple point targets was also performed. Five point targets were evenly spaced every about 10 degrees from about −20° to about +20°. Additionally, five point targets were spaced evenly in the axial direction from about 40 mm to about 80 mm, giving a total of about 125 point targets. A speckle target with an about 8 mm diameter spherical cyst located at about 60 mm depth was also simulated.
The phantom size was about 50 mm×about 50 mm×about 30 mm. 12 scatterers per resolution volume were used. The transmit and receive focus is set to an about 60 mm distant c-plane centered parallel to the face of the array. A pyramidal volume was scanned having a field of view of about 50°×about 50°×about 80 mm. The line spacing was set to about 0.5°. Therefore, each volume consists of about 101×101 image lines. Beamformed RF data from all image lines was assembled into a 3D volume. Inverse filters were created by taking the 3D Fourier Transform of the RF volume data from a single point target located on axis (about 0°, about 0°, about 60 mm) using both the fully-sampled array and the bowtie array. The inverse filtering operation was then applied in the frequency domain by first performing a 3D Fourier Transform on the RF volume data from the bowtie array and then multiplying the result with the inverse filter. An inverse 3D Fourier Transform was then applied to this result to produce a filtered 3D RF dataset. This 3D RF dataset then underwent envelope detection and logarithmic compression. Images of the point targets are shown in azimuthal and elevation B-scans and C-scans.
In
In
In
With inverse filtering, the bowtie array has clutter levels more comparable to the fully-sampled array. More clutter is seen in the spaces between the points in the range from about −10° to about +10°. Empirically, we observed that the presence and location of the clutter varies with the threshold applied to the inverse filter. Higher thresholds used with inverse filtering displaced the clutter from smaller angles near on-axis to larger lateral angles off-axis.
In this example, an orthogonal bowtie array was investigated in which all elements of a 2-D phased array are used either in transmit only or receive only. The performance of the bowtie array was analyzed using a k-space approach and evaluated with computer simulations using Field II pro were used to evaluate spatial resolution and contrast. A modified inverse filter approach was used to compensate for differences between the fully-sampled array and the bowtie array. The differences in the about −6, about −20, and about −40 dB beamwidths between the fully-sampled array and the bowtie array were considered small. However, these differences were most obvious in the anechoic sphere simulation. While the inverse filtering method did improve the CNR, the fully-sampled array still had CNRs that were about 15% to about 20% higher in the azimuthal and elevation B-scans. The C-scan CNRs were considered equivalent. Future simulations will involve evaluating performance with hyperechoic and hypoechoic targets and studying the impact of phase aberration on the bowtie array.
For these arrays, separate transmit and receive ASICs could be designed and optimized individually, enabling the flexibility to select high density low noise processes for the LV receive circuitry, and the best dedicated processes for the HV circuitry. In particular it is important to have access to higher voltage processes (e.g. above 40 Vpp) as these will greatly improve the overall sensitivity of the beamforming process thereby reducing noise and increasing contrast resolution which are critical parameters for expected diagnostic capability in medical imaging ultrasound. These higher voltage processes are inherently less highly integrated than more modern low voltage processes; therefore it is important to be able to separate high voltage and low voltage functionality such that these may be optimized independently to obtain the best possible performance of the overall system.
Array modules including the transducer elements and ASICs would then be assembled together to form the array. In our previous work [6, 9] we have demonstrated highly integrated and tileable transducer and ASIC array modules for constructing large area imaging apertures. For these bowtie arrays, sub-aperture or micro-beamforming processing of the data would still be performed. These array designs achieve comparable image quality to a fully-sampled array but afford the ability to develop separate transmit and receive electronics. This allows, for example the use of BCD HV CMOS processes with fully complementary NMOS and PMOS HV transistors for high quality output drivers with low distortion, while using very high-density processes to implement low noise preamplifiers and sigma-delta converters at every element. The bowtie array design may be useful for applications where size limitations are severe. These applications include intravascular ultrasound, intracardiac echocardiography, transesophageal echocardiography, endoscopic ultrasound, and high frequency (>15 MHz) imaging for ophthalmological applications.
An illustrative example of an 8×8 RBA is shown in
A potential limitation of the RBA 90 may be a low signal-to-noise ratio (SNR) because so few elements are used compare to a fully sampled array. To increase SNR, Barker codes with mismatched filters are used. Barker codes may be used due to their simplicity for implementation because of their biphasic nature. We used the 13-bit Barker code plotted in
Due to the high degree of sparseness, the point spread function contains high sidelobe and clutter levels. Signal processing and beamforming strategies are needed to suppress or eliminate clutter signals. A widely used approach is to apply apodization. Conventional apodization applies weighting to signals from individual elements. For example, a Hanning window as the weighting function w(x0)=0.5+0.5*cos(2*pi*xo/D) where x0 is the aperture coordinate and D is the aperture size. Near the focal region, the aperture and the beam have a Fourier Transform relationship. Because of this relationship, a Hanning weighting may also be achieved by convolving the image data with a 5-point kernel of [0.25, 0, 0.5, 0, 0.25] assuming the RF data has been captured with an appropriate line spacing. This 5-point kernel is convolved with the RF data set in for every axial depth and is equivalent to conventional apodization where weightings are applied to individual ultrasound elements. For 3-D imaging a two-dimensional version of the 5-point kernel can be used, and a 2-D dimensional convolution is carried out for each axial depth. This 5-point kernel is expanded to a 5×5 kernel:
In nonlinear apodization approach, data may be apodized uniformly and with a Hanning window using a convolution kernel similar to what is described above. Phase differences and similarities are used to identify and subsequently suppress sidelobe contributions to the signal. In this example, we apply nonlinear apodization to ultrasound signals from an RBA.
As an extension of NLA, we modified version called dual apodization with cross-correlation (DAX). DAX is a technique where received RF echo data is apodized with two different apodization functions. The pair of apodization which showed the highest gains in contrast-to-noise ratio (CNR) experimentally uses complementary square wave apodizations. After apodizing twice, the phase differences in the RF data can then be used to distinguish which echoes are clutter and which echoes are not using normalized cross-correlation at zero lag.
Simulations were carried out using Field II Pro. Simulations of a point target phantom where points were evenly spaced in a polar coordinate system. Single point targets located on axis (about 0°, about 0°, about 60 mm) and off-axis (about 40°, about 40°, about 60 mm). Main lobe widths (about −6 dB beamwidth) and integrated sidelobe ratios (ISLR) were calculated. Simulations involving multiple point targets was also performed. Five point targets were evenly spaced every about 10 degrees from about −40° to about +40°. Additionally, five point targets were spaced evenly in the axial direction from about 40 mm to about 80 mm. The transmit and receive focus is set to about 60 mm. A pyramidal volume was scanned having a field of view of about 90°×about 90°×about 100 mm. It was empirically determined that having a line spacing of about 0.5° was optimal. Therefore, each volume consists of about 181×about 181 image lines. Images of the point targets are shown in azimuthal and elevation B-scans as well as C-scans. Images with and without nonlinear apodization and DAX are shown.
3D ultrasound at the point of care may provide a valuable tool to clinicians for serially monitoring disease progression and response to treatment. To minimize the complexity of systems associated with fully-sampled 2D array, we simulated the use of rectangular boundary array combined with clutter suppression techniques. Performance was quantified in terms of spatial resolution and CNR. Comparisons with a fully sampled array were also performed.
In one example, an RBA may have more rows and columns, as shown in
An ultrasound transducer array is illustrated in
Each element 130 of both the first group 140 and the second group 150 may be configured to operate only in a first common mode that is one of transmit or receive, while each element 130 of both the third group 160 and the fourth group 170 may be configured to operate only in a second common mode that is the other of transmit or receive. That is, each of the elements 130 of both the first group 140 and the second group 150 may be configured only to operate as a transmit element (
Each of the elements 130 in each of the first group 140, second group 150, third group 160, and fourth group 170 may include a front surface through which the corresponding transmit or receive function is provided (this front surface being shown in
The ultrasound transducer array 100 of
In another example, the transmit/receive arrays may be arranged in a “stairstep”-like pattern and as shown in
Each element 230 of both the first group 240 and the second group 250 may be configured to operate only in a first common mode that is one of transmit or receive, while each element 230 of both the third group 260 and the fourth group 270 may be configured to operate only in a second common mode that is the other of transmit or receive. That is, each of the elements 230 of both the first group 240 and the second group 250 may be configured only to operate as a transmit element (
Each of the elements 230 in each of the first group 240, second group 250, third group 260, and fourth group 270 may include a front surface through which the corresponding transmit or receive function is provided (this front surface being shown in
For each of the first group 240 and the second group 250, the number of elements 230 in a given column is reduced proceeding in the direction of a central region of the ultrasound transducer array 200. For instance and as shown in
The ultrasound transducer array 100 of
In both of the two examples of
In yet another example, a multi-row boundary array may be built where a defocusing lens on each of the arms of the multi-row RBA may be attached to the front side of the transducer. Each row of the transmit RBA may be treated as one transmit element and each column of the RBA may be treated as one receive element. In
An ultrasound transducer array is illustrated in
The first group 340, second group 350, third group 360, and fourth group 370 each include a plurality of elements 330 (the elements 330 not being shown for the second group 350 (similarly configured to the first group 340) of for the third group 360 (similarly configured to the fourth group 370). Each element 330 of both the first group 340 and the second group 350 may be configured to operate only in a first common mode that is one of transmit or receive, while each element 330 of both the third group 360 and the fourth group 370 may be configured to operate only in a second common mode that is the other of transmit or receive. That is, each of the elements 330 of both the first group 340 and the second group 350 may be configured only to operate as a transmit element (
Each of the elements 330 in each of the first group 340, second group 350, third group 360, and fourth group 370 may include a front surface through which the corresponding transmit or receive function is provided (this front surface being shown in each of
Yet, in another example, a cross-section of an element 300 with a defocusing lens 400 is shown in
Yet, in another example, the shape/orientation of the defocusing lens 400′ may also be varied as shown in
Yet, in another example, a hybrid between a fully sampled array and an RBA, is shown in
A schematic of an ultrasound system is illustrated in
The components, steps, features, objects, benefits, and advantages that have been discussed are merely illustrative. None of them, nor the discussions relating to them, are intended to limit the scope of protection in any way. Numerous other examples are also contemplated. These include examples that have fewer, additional, and/or different components, steps, features, objects, benefits, and/or advantages. These also include examples in which the components and/or steps are arranged and/or ordered differently.
All of the features disclosed in this specification (including any accompanying exhibits, claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The disclosure is not restricted to the details of any foregoing examples. The disclosure extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
Those skilled in the art will appreciate that in some examples, the actual steps taken in the processes illustrated or disclosed may differ from those shown in the figures. Depending on the example, certain of the steps described above may be removed, others may be added. For example, the actual steps or order of steps taken in the disclosed processes may differ from those shown in the figure. Depending on the example, certain of the steps described above may be removed, others may be added. For instance, the various components illustrated in the figures may be implemented as software or firmware on a processor, controller, ASIC, FPGA, or dedicated hardware. Hardware components, such as processors, ASICs, FPGAs, and the like, can include logic circuitry. Furthermore, the features and attributes of the specific examples disclosed above may be combined in different ways to form additional examples, all of which fall within the scope of the present disclosure.
Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain examples include, while other examples do not include, certain features, elements, or steps. Thus, such conditional language is not generally intended to imply that features, elements, or steps are in any way required for one or more examples or that one or more examples necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, or steps are included or are to be performed in any particular example. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Likewise, the term “and/or” in reference to a list of two or more items, covers all of the following interpretations of the word: any one of the items in the list, all of the items in the list, and any combination of the items in the list. Further, the term “each,” as used herein, in addition to having its ordinary meaning, can mean any subset of a set of elements to which the term “each” is applied. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application.
Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain examples require the presence of at least one of X, at least one of Y, and at least one of Z.
Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this disclosure are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.
Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount. As another example, in certain examples, the terms “generally parallel” and “substantially parallel” refer to a value, amount, or characteristic that departs from exactly parallel by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.
All articles, patents, patent applications, and other publications that have been cited in this disclosure are incorporated herein by reference.
In this disclosure, the indefinite article “a” and phrases “one or more” and “at least one” are synonymous and mean “at least one”.
Relational terms such as “first” and “second” and the like may be used solely to distinguish one entity or action from another, without necessarily requiring or implying any actual relationship or order between them. The terms “comprises,” “comprising,” and any other variation thereof when used in connection with a list of elements in the specification or claims are intended to indicate that the list is not exclusive and that other elements may be included. Similarly, an element preceded by an “a” or an “an” does not, without further constraints, preclude the existence of additional elements of the identical type.
The abstract is provided to help the reader quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, various features in the foregoing detailed description are grouped together in various examples to streamline the disclosure. This method of disclosure should not be interpreted as requiring claimed examples to require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed example. Thus, the following claims are hereby incorporated into the detailed description, with each claim standing on its own as separately claimed subject matter.
The various illustrative logical blocks, modules, routines, and algorithm steps described in connection with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. The described functionality can be implemented in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosure.
Moreover, the various illustrative logical blocks and modules described in connection with the embodiments disclosed herein can be implemented or performed by a machine, such as a general purpose processor device, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor device can be a microprocessor, but in the alternative, the processor device can be a controller, microcontroller, or state machine, combinations of the same, or the like. A processor device can include electrical circuitry configured to process computer-executable instructions. In another embodiment, a processor device includes an FPGA or other programmable device that performs logic operations without processing computer-executable instructions. A processor device can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Although described herein primarily with respect to digital technology, a processor device may also include primarily analog components. For example, some or all of the signal processing algorithms described herein may be implemented in analog circuitry or mixed analog and digital circuitry. A computing environment can include any type of computer system, including, but not limited to, a computer system based on a microprocessor, a mainframe computer, a digital signal processor, a portable computing device, a device controller, or a computational engine within an appliance, to name a few.
The elements of a method, process, routine, or algorithm described in connection with the embodiments disclosed herein can be embodied directly in hardware, in a software module executed by a processor device, or in a combination of the two. A software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of a non-transitory computer-readable storage medium. An exemplary storage medium can be coupled to the processor device such that the processor device can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor device. The processor device and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In the alternative, the processor device and the storage medium can reside as discrete components in a user terminal.
Any combination of above embodiments are within the scope of this disclosure.
This patent application is a non-provisional patent application of, and claims the benefit of, co-pending U.S. Provisional Patent Application No. 63/074,931, that was filed on Sep. 4, 2020, and the entire disclosure of which is hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 63074931 | Sep 2020 | US |
