Systems and methods for controlling a transducer module that generates focused ultrasound waves

Abstract

A phased array ultrasonic system includes one or more ultrasonic array modules having respective array elements, each connected to a respective switch. Each array module receives a set of drive signals, each having a respective phase value, and the set of drive signals is provided to each switch. The switches are controlled so that the drive signal provided to a given array element has a phase value closest to an ideal phase value for focusing ultrasonic energy at a selected focal position. At least two of the array modules each receive a unique module-specific set of drive signals, each having a unique phase set. The unique set of phase values ​​can be determined based on the set of ideal phases to focus ultrasonic energy at one or more positions, such as a selected focal position or a selected focal region.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 438,922, entitled "SYSTEMS AND METHODS FOR CONTROLLING TRANSDUCER MODULES FOR GENERATING FOCUSED ULTRASOUND," filed January 13, 2023, the entire contents of which are incorporated herein by reference.

[0002] TECHNICAL FIELD This disclosure relates to ultrasound-based therapy and imaging. More particularly, this disclosure relates to ultrasound systems and methods. [Background technology]

[0003] The use of ultrasound for diagnostic and therapeutic applications has been extensively studied over the past several decades. In addition to its routine use in diagnosing disease, focused ultrasound beams have been found to be effective for, for example, tumor ablation, thrombolysis, drug delivery, gene therapy, vascular occlusion, localized enhancement of blood-brain barrier permeability, and neuromodulation. Focused ultrasound as a therapeutic course offers an effective method for neutralizing the effects of pathological tissues, while offering the same advantages as traditional interventional therapies in terms of minimal side effects and significantly reduced recovery times.

[0004] Over the past 25 years, phased-array transducers have emerged as a means of generating ultrasound fields. These devices offer electronic beam steering, thus eliminating the need for moving parts and allowing compensation for distortions induced by intervening tissue. To develop a system with complete control over focal position, a large number of elements is required. For complete electronic focal steering, the maximum center-to-center element spacing is λ / 2, where λ is the wavelength. For treatment frequencies ranging from 0.2 to 10 MHz, this condition requires an element spacing of approximately 3 mm to 0.075 mm. To generate a therapeutically significant amount of power and adequate focal gain, a large number of independently driven transducer elements is required.

[0005] This creates challenges related to the cost and size of the cable assembly and driving electronics that provide the RF signal. Summary of the Invention

[0006] A phased array ultrasonic system includes one or more ultrasonic array modules having respective array elements connected to respective switches. Each array module receives a set of drive signals, each having a respective phase value, and the set of drive signals is provided to each switch. The switches are controlled so that the drive signal provided to a given array element has a phase value closest to an ideal phase value for focusing ultrasonic energy at a selected focal position. At least two of the array modules each receive a unique module-specific drive signal set, each having a unique phase set. The given unique set of phase values ​​can be determined based on an ideal phase set for focusing ultrasonic energy at one or more positions, such as a selected focal position or a selected focal region.

[0007] Accordingly, in a first aspect, there is provided a phased array ultrasound system comprising: support; a plurality of ultrasonic modules mechanically supported by a support, each ultrasonic module comprising a respective array of ultrasonic elements, each ultrasonic element being electrically connected to an output of a respective switch uniquely associated with the ultrasonic element; and control and drive electronics configured to generate and send a respective set of drive signals to each ultrasonic module, the control and drive electronics configured to provide a set of drive signals to each switch of the ultrasonic module; The control and drive electronics may control and drive each switch such that actuation of the switch associated with a given ultrasonic array element selects delivery of any one drive signal of the set of drive signals to a given ultrasonic array element of a given ultrasonic module; For each ultrasonic module of the plurality of ultrasonic modules: the number of drive signals in the set of drive signals provided to the ultrasonic module is less than the number of ultrasonic elements in the ultrasonic module; Each drive signal in the set of drive signals has a respective phase, such that the set of drive signals has an associated set of phase values; For at least two ultrasonic modules of the plurality of ultrasonic modules, the set of phase values ​​associated with the set of drive signals provided to the ultrasonic modules is a unique set of phase values ​​customized for the ultrasonic module; The control and drive electronics are configured to control each switch of each ultrasonic module so that, for each switch, the drive signal provided to the ultrasonic element associated with the switch is a drive signal from the set of drive signals provided to the switch and has a phase value that is closest to an ideal phase associated with the ultrasonic element for focusing ultrasonic energy at a selected focal position.

[0008] In some exemplary implementations of the system, the control and drive electronics are configured such that a unique set of phase values ​​associated with a given ultrasonic module is determined based on a set of ideal phases respectively associated with the array elements of the given ultrasonic module to focus ultrasonic energy at multiple locations within a selected region. The control and drive electronics can be configured such that the selected region is associated with a specific subject. The control and drive electronics are configured such that the selected region spans a planned target volume associated with the specific subject.

[0009] In some example implementations of the system, the control and drive electronics are configured such that a unique set of phase values ​​associated with a given ultrasonic module is determined based on a set of ideal phases respectively associated with the array elements of the given ultrasonic module to focus the ultrasonic energy at a selected focal position.

[0010] The control and drive electronics can be configured such that the unique set of phase values ​​associated with a given ultrasonic module includes a maximum phase value, a minimum phase value, and at least one intermediate phase value between the maximum and minimum phase values, each intermediate phase value lying within a phase range spanning the maximum and minimum ideal phases of the set of ideal phases associated with the given ultrasonic module.

[0011] The control and drive electronics can be configured such that a unique set of phase values ​​associated with a given ultrasonic module minimizes an aggregate phase error measure, where the aggregate phase error measure is determined based on the phase error associated with each ultrasonic element of the given ultrasonic module, and each phase error is determined, for a given ultrasonic element of the given ultrasonic module, by calculating the difference between the phase value of the drive signal provided to the given ultrasonic element and an ideal phase value associated with the given ultrasonic element.

[0012] In some exemplary implementations of the system, the control and drive electronics are configured such that each drive signal is a pulsed drive signal for generating pulsed ultrasonic energy, and each set of drive signals is delivered to a respective ultrasonic module with a module-specific delay, and each module-specific delay is selected to facilitate temporal alignment of the pulsed ultrasonic energy from the ultrasonic module at a selected focal position.

[0013] In some exemplary implementations of the system, the support is a conformal headset and the selected focal position is an intracranial focal position.

[0014] In some exemplary implementations of the system, for at least one ultrasound module, each drive signal is provided to an equal number of ultrasound elements.

[0015] In some example implementations of the system, for at least one ultrasonic module, at least two drive signals are provided, each for a different number of ultrasonic elements.

[0016] In some example implementations of the system, at least two ultrasound modules have different numbers of ultrasound elements.

[0017] In some exemplary implementations of the system, at least two ultrasound modules are provided with different numbers of drive signals.

[0018] In some example implementations of the system, for at least two ultrasonic modules, the number of drive signals provided to each ultrasonic module depends on the number of ultrasonic elements in each ultrasonic module and / or the span of ideal phase values.

[0019] In some exemplary implementations of the system, the ratio of the number of ultrasonic elements to the number of drive signals is at least 16 for at least one module.

[0020] In some exemplary implementations of the system, the switches are optically configurable, and the control and drive electronics include a light source controllable to deliver an optical signal for configuring the switches to select an appropriate drive signal.

[0021] In some exemplary implementations of the system, each unique set of phase values ​​is determined based on an acoustic model that characterizes the spatial variation of the acoustic properties of the tissue region to be insonified.

[0022] In another aspect, there is provided a method for generating focused ultrasound waves from an ultrasound system comprising a support and a plurality of ultrasound modules mechanically supported by the support, each ultrasound module comprising a respective array of ultrasound elements, each ultrasound element in electrical communication with an output of a respective switch uniquely associated with the ultrasound element, the method comprising: For each ultrasonic module: generating a set of drive signals for the ultrasonic module, each drive signal having a respective phase value, wherein the number of drive signals in the set of drive signals provided to the ultrasonic module is less than the number of ultrasonic elements in the ultrasonic module; providing a set of drive signals for each switch of the ultrasonic module; controlling a switch of the ultrasound module such that, for a given array element of the ultrasound module, the drive signal provided to the given array element is a drive signal from the set of drive signals having a phase value that is closest to an ideal phase value associated with the array element that focuses the ultrasound energy at the selected focal position; For at least two ultrasonic modules of the plurality of ultrasonic modules, the set of phase values ​​associated with the set of drive signals provided to the ultrasonic module is a unique set of phase values ​​customized for the ultrasonic module.

[0023] In some exemplary implementations of the method, a unique set of phase values ​​associated with a given ultrasound module is determined based on a set of ideal phases respectively associated with array elements of the given ultrasound module to focus ultrasound energy at multiple locations within a selected region. The selected region may be associated with a specific subject. The selected region may span a planned target volume associated with the specific subject.

[0024] In some example implementations of the method, a unique set of phase values ​​associated with a given ultrasound module is determined based on a set of ideal phases respectively associated with the array elements of the given ultrasound module to focus the ultrasound energy at a selected focal position.

[0025] The unique set of phase values ​​associated with a given ultrasonic module can include a maximum phase value, a minimum phase value, and at least one intermediate phase value between the maximum and minimum phase values, each intermediate phase value being within a phase range spanning the maximum and minimum ideal phases of the set of ideal phases associated with the given ultrasonic module.

[0026] The unique set of phase values ​​associated with a given ultrasonic module can minimize an aggregate phase error measure, where the aggregate phase error measure is determined based on the phase error associated with each ultrasonic element of the given ultrasonic module, and each phase error is determined, for a given ultrasonic element of the given ultrasonic module, by calculating the difference between the phase value of the drive signal provided to the given ultrasonic element and an ideal phase value associated with the given ultrasonic element.

[0027] In some exemplary implementations of the method, each drive signal is a pulsed drive signal for generating pulsed ultrasonic energy, and each set of drive signals is delivered to a respective ultrasonic module with a module-specific delay, and each module-specific delay is selected to facilitate temporal alignment of the pulsed ultrasonic energy from the ultrasonic module at a selected focal position.

[0028] In some exemplary implementations of the method, the support is a conformal headset and the selected focal position is an intracranial focal position.

[0029] In some exemplary implementations of the method, each unique set of phase values ​​is determined based on an acoustic model that characterizes the spatial variation of the acoustic properties of the tissue region to be insonified.

[0030] In another aspect, a phased array ultrasound system is provided, comprising: an array of ultrasonic elements, each ultrasonic element electrically connected to an output of a respective switch uniquely associated with the ultrasonic element; control and drive electronics configured to generate and deliver a set of drive signals and deliver the set of drive signals to each switch; The control and drive electronics are capable of controlling each switch to select delivery of any one drive signal of the set of drive signals to a given ultrasonic array element by actuation of the switch associated with the given ultrasonic array element; the number of drive signals in the set of drive signals is less than the number of ultrasonic elements in the array; each drive signal of the set of drive signals having a respective phase such that the set of drive signals has an associated set of phase values, the set of phase values ​​being determined based on a set of ideal phases respectively associated with array elements of the array to focus the ultrasonic energy at one or more locations; The control and drive electronics are configured to control each switch, and the drive signal provided to the ultrasonic element associated with the switch is a drive signal from the set of drive signals provided to the switch that has a phase value closest to the ideal phase associated with the ultrasonic element at the selected focal position.

[0031] In another aspect, a method for generating focused ultrasound waves from an array of ultrasound elements, each ultrasound element in electrical communication with an output of a respective switch uniquely associated with the ultrasound element, is provided, the method comprising: generating a set of drive signals, each drive signal having a respective phase value, whereby the set of drive signals has an associated set of phase values, the number of drive signals in the set of drive signals being less than the number of ultrasonic elements in the array of ultrasonic elements, the set of phase values ​​being determined based on a set of ideal phases respectively associated with array elements of the array to focus ultrasonic energy at one or more locations; providing a set of drive signals for each switch; controlling the switch such that, for a given array element, the drive signal provided to the given array element is a drive signal from the set of drive signals having a phase value that is closest to an ideal phase value associated with the array element to focus the ultrasound energy at a selected focal position.

[0032] A further understanding of the functional and advantageous aspects of the present disclosure can be realized by reference to the following detailed description and drawings. [Brief explanation of the drawings]

[0033] Embodiments will now be described, by way of example only, with reference to the drawings in which:

[0034] [Figure 1A] 1 illustrates an exemplary ultrasound system with a reduced number of drive signals having a preselected fixed phase.

[0035] [Figure 1B] 1B illustrates an exemplary method of operating the system shown in FIG. 1A.

[0036] [Figure 2A] 1B illustrates the improved focusing obtained using the system of FIG. 1A. [Figure 2B]1B illustrates the improved focusing obtained using the system of FIG. 1A.

[0037] [Figure 3A] 1 illustrates an exemplary improved ultrasound system with a reduced number of drive signals with phases determined based on a selected focal spot position.

[0038] [Figure 3B] 3B illustrates an exemplary method of operating the system shown in FIG. 3A.

[0039] [Figure 4A] 1 illustrates an exemplary modular ultrasound system with a reduced number of drive signals with module-specific phases determined based on a selected focal spot position.

[0040] [Figure 4B] 10 illustrates an exemplary method for selectively controlling the switches of a given ultrasound module to deliver the appropriate drive signal to each element.

[0041] [Figure 5] FIG. 1 is a schematic diagram of an exemplary modular intracranial focused ultrasound system.

[0042] [Figure 6] FIG. 1 is a photograph of another exemplary modular intracranial focused ultrasound system, showing an internal view of a patient-customized ultrasound headset.

[0043] [Figure 7] 1 illustrates an exemplary system for performing transcranial diagnostic and / or therapeutic procedures. DETAILED DESCRIPTION OF THE INVENTION

[0044] Various embodiments and aspects of the present disclosure are described with reference to the details discussed below. The following description and drawings are illustrative of the present disclosure and should not be construed as limiting the disclosure. Numerous specific details are set forth in order to provide a thorough understanding of various embodiments of the present disclosure. However, in some cases, well-known or conventional details are not described in order to provide a concise discussion of the embodiments of the present disclosure.

[0045] As used herein, the terms "comprises" and "comprising" should be interpreted as inclusive and not limiting, and not exclusive. Specifically, when used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps, or components are included. These terms should not be interpreted to exclude the presence of other features, steps, or components.

[0046] As used herein, the word "exemplary" means "serving as an example, instance, or illustration," and should not be construed as preferred or advantageous over other configurations disclosed herein.

[0047] As used herein, the terms "about" and "approximately" are meant to encompass variations that may exist at the upper and lower limits of a range of values, such as variations in properties, parameters, and dimensions. Unless otherwise specified, the terms "about" and "approximately" mean ±25 percent or less.

[0048] Unless otherwise specified, it should be understood that a specified range or group is a shorthand way of referring not only to each member of the range or group individually, but also to all possible sub-ranges or sub-groups contained therein, and sub-ranges or sub-groups contained therein as well. Unless otherwise specified, the present disclosure relates to and expressly incorporates each and every specific member and combination of sub-ranges or sub-groups.

[0049] As used herein, the term "on the order of" when used in conjunction with an amount or parameter refers to a range ranging from about one-tenth to ten times the stated amount or parameter.

[0050] Unless otherwise defined, all technical and scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art. Unless otherwise indicated by context or otherwise, the following terms used herein shall have the meanings set forth below:

[0051] As described above, when delivering therapeutic ultrasound at frequencies in the range of 0.2 to 10 MHz using a phased array device, it is necessary to maintain an element spacing of less than λ / 2, so an element spacing of approximately 3 mm to 0.075 mm is required. If the therapeutic transducer array is large, a large number of individual RF drive signals need to be sent to the array elements, imposing costs, size, and complexity burdens on the cable assembly and drive electronics. To overcome this problem, Caulfield et al. (R. E. Caulfield, X. Yin, J. Juste, and K. Hynynen, "A novel phase assignment protocol and driving system for a high-density focused ultrasound array," IEEE Trans. Ultrason. Ferroelectr. Freq. Control, vol. 54, no. 4, pp. 793-801, 4 / 2007 2007) proposed that the therapeutic phased array ultrasound system can be simplified by reducing the number of RF drive signals.

[0052] Caulfield proposed a configuration schematically shown in the flowcharts shown in FIGS. 1A and 1B. As shown in step 200 of FIGS. 1A and 1B, an N-element phased array 100 (in the illustrated example, N = 32) is provided such that each array element 110 is connected to the output of a respective Mx1 switch 120 (in the illustrated example, M = 4). As will be described later, each switch is used to select an appropriate drive signal from a reduced set of drive signals M, each drive signal has a different discrete phase, M < N, and as a result, the reduced set of drive signals is used to generate focused ultrasound from the ultrasound array 100.

[0053] The reduced set of M phases for generating the drive signals is predetermined by dividing a unit circle into M phase increments, without considering the desired focal position or area, to obtain a set of evenly spaced predetermined phases: (m-1)*360° / M, m∈(1,M), as shown at 130 in Figure 1A and step 210 in Figure 1B. In the exemplary system shown in Figure 1A when M=4, the four discrete phases are 0, 90°, 180°, and 270°.

[0054] Next, as shown in step 220 of Figure 1B, the M phases are used to generate M drive signals for driving the ultrasonic array 100. Figure 1A shows the generation of four drive signals 140, each with a different discrete (quantized) phase. The drive signals 140 are amplified via amplifiers 150.

[0055] 1A and 1B, step 230, are provided to each of the N switches 120, such that each switch 120 can deliver any one of the M drive signals to the array element connected to its output. In the example shown in FIG. 1, each of the 32 elements is connected via a respective signal path 115 to a respective 4x1 switch, which is configurable to send one of the four drive signals to the element.

[0056] 1B , the switch 120 is configured to select drive signals for delivery to the array elements 110. First, if continuous phase selection is possible, the "ideal" phase is calculated for each array element 110 to generate a focal spot at the selected location. For each element 110 of the array, the switch 120 associated with the element is programmed to select an appropriate drive signal from the M drive signals by comparing the M phases associated with the M drive signals to the "ideal" phase, and to select the drive signal having a phase closest to the ideal phase.

[0057] Caulfield's system implementation uses a programmable latch 160 to provide output lines for configuring the switches according to the desired set of phases, the latch being programmed by receiving phase selection data from a computer 170. While FIG. 1A shows a single connection 165 between the latch and a given switch 120, Caulfield's system is based on the use of four switches per array element, with the outputs of the four switches connected in parallel to a given array element and configured by the four connections provided by the latch 170. Furthermore, Caulfield employs multiple latches to configure the complete set of array elements, with each latch being loaded sequentially.

[0058] As can be seen in Figure 1A, instead of requiring a full set of N drive signals for continuous phase resolution and focusing ultrasound energy at a selected focal spot, Caulfield's method uses a reduced set of M unique drive signals. By connecting elements with similar phase values ​​to a single drive line, a significant reduction in the number of input lines can be achieved, thus significantly reducing the cost per channel while still providing the full benefits of electronic beam steering and distortion compensation. Caulfield demonstrated that by connecting all transducer elements to four drive lines with phase angles of 0, 90, 180, and 270 degrees, as shown in Figures 2A and 2B, he could achieve focal intensities greater than 80% of those obtained with perfect phase.

[0059] However, the present inventors have discovered that this performance can be further improved by using an approach orthogonal to that of Caulfield. Indeed, while Caulfield's approach selects a fixed, predetermined set of phases for the M drive signals that is independent of the focal spot location within the tissue being insonified and independent of the spatial heterogeneity of the tissue's acoustic properties (focal spot independence, tissue acoustic heterogeneity independence), the present inventors have recognized that the focusing performance of an ultrasound array can be further improved by employing (customizing) a phase set M that is generated based on a selected focal spot location, or based on the focus within a selected region, and optionally based on the spatial heterogeneity of the tissue's acoustic properties. This allows the phase to be calculated to reduce phase errors and improve the focal strength. As described in more detail below, such improvements are particularly beneficial for practical 2D and 3D phased arrays, which are modular in nature.

[0060] An exemplary implementation of such an embodiment is shown in the exemplary system illustrated in FIG. 3A and the flowchart illustrated in FIG. 3B. Referring first to FIG. 3A, in stark contrast to the Caulfield system illustrated in FIG. 1A, the four phases of the drive signal are calculated based on focus position or on focus within a selected region. As can be seen, the four phases are configured for a given focus position or for focusing with a selected region via connection to control and processing circuitry 175 (examples of which are described in more detail below). An exemplary method for calculating a set of focus-position-dependent or focus-region-dependent phases is described in more detail below.

[0061] The flowchart in FIG. 3B illustrates an exemplary method for generating a set of M drive signals with M respective phases determined based on a selected focal position or selected region and configuring a switch so that the appropriate drive signal is delivered to each array element. Unlike Caulfield's method, in which the selected focal position is used only when calculating the ideal phase value used to configure the switch for a given array element, the method illustrated in FIG. 3B determines a reduced set of phase values ​​for M based on the selected focal position or a predetermined region that can be focused, as shown in steps 310 and 320. The ideal phase values ​​associated with the set of array elements for focusing ultrasound energy from the array elements at multiple locations within the selected focal position or selected region, determined in step 310, are used to select the appropriate set of M phase values ​​in step 320. The number of phase values ​​M (i.e., the number of drive signals) may depend on the span of the set of ideal phases.

[0062] When ideal phase values ​​are defined based on a selected region, as opposed to being defined based on a single desired focus position, the ideal phase values ​​may be calculated, for example, based on multiple focus positions present within the selected region (e.g., a set of representative focus positions densely or sparsely spread across the selected region). For example, a subset of ideal phase values ​​may be calculated for each position within the selected region, and the subsets of ideal phase values ​​may be aggregated to define a final set of ideal phase values ​​associated with the selected region.

[0063] The selected region may be defined without using information associated with a particular subject or treatment plan, for example, as a geometric region defined relative to the ultrasound array. In other exemplary embodiments, the selected region may be patient-specific and may be defined based on information related to a particular subject or treatment plan. For example, the selected region may surround or be located within a selected anatomical region or a selected treatment target region, such as a tumor or a region surrounding a tumor with a predetermined margin.

[0064] These M focus position or focus region specific phase values ​​are then used to generate M respective drive signals which are fed to switches in steps 330 and 340 which control the switches in step 350 to provide each array element with a drive signal whose phase most closely matches its respective ideal phase value.

[0065] The M phases can be generated from a set of ideal phases according to a wide range of implementations. The M phases can be generated based on a set of ideal phase values ​​such that the focal intensity at the selected focal point exceeds the focal intensity obtained from the Caulfield method of dividing a unit circle into M phase increments.

[0066] For example, a range of ideal phase values ​​(e.g., maximum and minimum ideal phase values) can be used to determine a phase range for generating the M phases. For example, in one implementation, the phase range corresponding to the ideal phase values ​​can be divided into equal increments to generate the M phases. In some exemplary embodiments, each of the M phases between the maximum and minimum values ​​of the M phases is constrained to be within the ideal phase range. In other exemplary implementations, a nonlinear fitting method can be used to select the M phase values. For example, some of the M phase values ​​can be clustered in an area of ​​the phase range that has a higher density of ideal phase values.

[0067] In some example implementations, an optimization algorithm may be employed to select the M phases based on the ideal phase values. For example, when M drive signals using the M phases are each delivered to a switch, and the switch is configured to deliver to each array element a drive signal having a phase value closest to the ideal phase value, the M phase values ​​may be selected such that the M phase values ​​maximize the focal intensity. In some examples, the M phase values ​​may be selected as those that minimize a measurement generated based on a phase error calculated as the difference between the ideal phase value and the closest of the M phase values ​​when summed across all array elements (e.g., the sum of the squares of the phase value differences). It will be appreciated that many other methods may be used to select the M phases based on a set of ideal phases.

[0068] While the exemplary system shown in FIG. 3A illustrates a specific example in which four phases (and their respective drive signals) are calculated based on a selected focal position or multiple focal positions within a selected region, it will be understood that any number of phases (and their respective drive signals) may be used, provided that the number is less than the number of elements in the array.

[0069] Although an Mx1 switch is shown schematically as being connected to each array element 110, it will be appreciated that this function may be implemented according to several different configurations, such as, for example, a single Mx1 switch, or M 1x1 switches with outputs connected in parallel.

[0070] While FIG. 3A schematically illustrates an exemplary configuration in which the switch 120 is programmed (configured) by intermediate drive signal selection electronics (e.g., a latch), it will be understood that the switch may be interfaced directly with a computing system such as the control and processing circuit 175.

[0071] Additionally, although a single connection line is shown between the drive signal selection electronics (e.g., a programmable latch) and the switch 120, each switch may be configured with multiple control lines connecting the switch to the drive signal electronics 160.

[0072] Because a given set of switches can be implemented with only one or a few TTL lines (or radio signals), switching speeds can be very fast compared to more conventional methods of performing electronic focusing.

[0073] It will be understood that the switches can be any type of configurable switch, for example, solid-state, mechanical, or other types of switches such as optically controlled switches. The switches can be made from discrete components or can be application specific circuits (ASICs) designed specifically for this application. Electrical and electronic control lines can be used in series or parallel to address each switch and set it to the appropriate connection before each sonication. In some exemplary embodiments, the switches can be wireless, such as light-actuable switches, where the light is delivered via fiber optics or other optical means such as a laser beam or projection of a light pattern.

[0074] RF signals with predetermined phase angles can be generated by a variety of means, including but not limited to oscillators, field programmable processors (FPCs), and ASICs. The signals and their timing can be controlled by a central processing unit or through multiple sub-units when fast switching speeds are required or beneficial.

[0075] In some exemplary embodiments, the exemplary embodiment shown in Figures 3A and 3B can be adapted for use with a modular phased array system. Such a modular phased array system includes a set of phased array ultrasonic modules, each including a respective array of ultrasonic elements, and each ultrasonic module is provided with a set of drive signals for generating and focusing ultrasonic waves according to the methods described above. As described in further detail below, in some exemplary implementations, at least two of the modules are provided with respective sets of drive signals that are module-specific. That is, the individual phase sets associated with each set of drive signals are customized or unique to a particular module. At least two of the modules can have different numbers of array elements.

[0076] 4A shows a schematic diagram of an exemplary modular phased array ultrasound system including two modules, module A (100A) and module B (100B), where module A is provided with four different drive signals having respective phases A1, A2, A3, and A4, and module B is provided with four different drive signals having respective phases B1, B2, B3, and B4, with the number of drive signals provided to each module being less than the number of array elements in each module.

[0077] 3B, a selected focal position, or multiple focal positions within a selected region (as described above), are used to determine both a set of phases A1, A2, A3, and A4 for generating the drive signals sent to module A and a set of phases B1, B2, B3, and B4 for generating the drive signals sent to module B. Phases A1, A2, A3, and A4 are calculated based on a set of ideal phases associated with the elements of module A to focus ultrasonic energy within the selected focal position 180 or selected region. Similarly, phases B1, B2, B3, and B4 are calculated based on a set of ideal phases associated with the elements of module B to focus ultrasonic energy within the selected focal position 180 or selected region.

[0078] Any of the above example methods, or variations thereof, may be used to calculate a customized set of phases for modules. Thus, the phases used in the drive signals provided to module A are customized for module A, and the phases used in the drive signals provided to module B are customized for module B, such that the set of phases A1, A2, A3, and A4 is different from the set of phases B1, B2, B3, and B4. While some example implementations involve the calculation and use of a customized set of phases for each module, other example implementations involve the calculation and use of a customized set of phases for any two or more of the modules in an array of modules.

[0079] As shown, each module has a respective set of switches 120A and 120B, which are configured according to per-module signal selection electronics 165A and 165B such that the drive signal delivered to a given array element of module A is selected from the four drive signals (having phases A1, A2, A3, and A4) having a phase value closest to the element's ideal phase value, and the drive signal delivered to a given array element of module B is selected from the four drive signals (having phases B1, B2, B3, and B4) having a phase value closest to the element's ideal phase value. Selection of appropriate drive signals via configuration of the various switches of module A is shown in FIG. 4B for an exemplary implementation in which drive signals having only three different respective phases A1, A2, and A3 are provided to each switch of module A. It will be understood that drive signals may be selected for at least one ultrasonic module such that at least two drive signals are provided to different numbers of ultrasonic array elements, respectively.

[0080] While FIG. 4A shows an exemplary case where each module has its own signal selection electronics 165A and 165B, it will be understood that these components may be integrated into a single subsystem or directly with the control and processing circuitry 175.

[0081] While Figure 4A illustrates a non-limiting exemplary system having two modules, it will be understood that this exemplary embodiment may be adapted to a modular ultrasound system having any number of modules. More generally, in a modular phased array system having K modules, where each module is denoted k, k ∈ [1, K], each module is provided with a respective set of M drive signals, each drive signal having a respective phase φ m,k, m ∈ [1, M k]. Furthermore, any two modules may have different numbers of drive signals, e.g., M k is a different value for at least two different values ​​of k. In some exemplary implementations, the number of drive signals provided to each ultrasound module may depend on the number of ultrasound elements in each ultrasound module.

[0082] The ideal phase of each element of each transducer module can be determined by calculating the distance x(n,k) from the surface of each transducer element in module k to a selected focal position 180 (or to multiple positions within a selected region), where n∈[1,N] is the count of array elements in the module, as shown in Figure 4A. Assuming the average ultrasonic propagation speed in the medium is v and the ultrasonic frequency is f, the phase difference (φ) of each transducer element relative to, say, element 1 is given by: φ(n,k)=2Π(x(n,k)-x(1,k)) / (v / f)

[0083] Here the phase is constrained to its principal value and is therefore a wrapped phase.

[0084] After the ideal phases are calculated for all transducer elements of a given module, the maximum and minimum ideal phases for the module can be used to determine the range of phases spanned by M phase signals φm,k. In this case, each element of module (n,k) is connected via a respective switch to a drive signal having a phase φm,k that is closest to the element's ideal phase value. Similar calculations can then be made for other ultrasonic modules in the system.

[0085] If short sonication periods of only a few cycles are used, the sonication start time of each module can be adjusted so that the acoustic bursts reach the indented target at the same time.

[0086] This time delay can be calculated from the average time of flight of each module. The time (t(n,k)) for an ultrasonic burst to travel from element n,k of module k to the selected focal position is t(n,k) = x(n,k) / v. The average time of flight of each module t ave can be used to calculate the time delay required for each module to ensure that each sound burst reaches the target at the same time. For example, t for module 2 ave If (2) is the longest, the delay (d(k)) to other modules can be calculated using the following formula: d(k)=t ave (k)-t ave (2), k=1~K K is the total number of modules. Thus, each module can be individually controlled such that the start and end of sonication from each module can be controlled to include a relative delay in sonication, thereby facilitating improved focusing.

[0087] 3A and 4A show one-dimensional transducer arrays, it will be appreciated that exemplary embodiments of the present invention may be adapted to two-dimensional transducer arrays.

[0088] The above-described exemplary embodiments of modular ultrasound arrays are particularly useful for applications involving intracranial delivery of focused ultrasound. Examples of modular ultrasound devices for delivering focused intracranial ultrasound are shown in Figures 5 and 6. For example, a conformal brain therapy system having 64 subarrays of 64 elements has been constructed and described by Adam et al. (C. Adams et al., "Implementation of a Skull-Conformal Phased Array for Transcranial Focused Ultrasound Therapy," (in eng), IEEE Trans Biomed Eng, vol. 68, no. 11, pp. 3457-3468, Nov 2021, doi: 10.1109 / tbme.2021.3077802).

[0089] Such systems may be adapted to employ embodiments of the present disclosure to reduce the number of drive signals delivered to the ultrasound modules while facilitating accurate focusing. In such cases, the complexity of the system can be significantly reduced by selectively optimizing the set of phases used to generate the reduced number of drive signals for each module (or at least two modules).

[0090] It should be noted that the optimization algorithm used to select the different sets of phases for each module can advantageously take into account tissue heterogeneity, such as the skull for transcranial sonication, which can distort ultrasound propagation. For example, ideal phases can be determined based on an acoustic model that characterizes the spatial variation in the acoustic properties of the tissue region being insonified. For example, image data (e.g., MR, CT, optical, x-ray, and ultrasound) can be processed to identify subregions of known tissue types within the region being insonified, and a model can be generated by associating known acoustic properties corresponding to the tissue type of the subregion with each subregion. In one exemplary embodiment, the ideal phase calculation can take into account tissue heterogeneity, such as the skull, using data obtained from a CT scan by first segmenting the CT scan to identify known tissue types and then constructing an acoustic model that uses sound speed values ​​for various tissue types from the literature and density values ​​from a calibrated CT scan. For the skull, sound speed and attenuation are density-dependent.これClementとHynynen(GT Clement and K. Hynynen, "A non-invasive method for focusing ultrasound through the human skull," Phys. Med Biol, vol. 47, no. 8, pp. 1219-1236, 4 / 21 / 2002 2002; physical skull properties,” Ultrasound Med Biol, vol. 28, no. 5, pp. 617-624, 5 / 2002 2002). longitudinal transmission of freshly excised human skulls," Phys Med Biol, vol. 56, no. 1, pp. 219-250, 1 / 7 / 2011 2011)Shear wave propagation can also be modeled (e.g., G.T. Clement, P.J. White, and K. Hynynen, "Enhanced ultrasound transmission through the human skull using shear mode conversion," J. Acoust. Soc. Am, vol. 115, no. 3, pp. 1356-1364, March 2004, 2004; and P.J. White, G.T. Clement, and K. Hynynen, "Longitudinal and shear mode ultrasound propagation in human skull bone," Ultrasound Med. Biol, vol. 32, no. 7, pp. 1085-1096, July 2006, 2006). Wave propagation can be modeled using ray tracing, spectral methods, full-wave simulations, or inverse methods using a point source at an indented focus, which then propagates the wave to each of the array elements. For each of these methods, a relative phase shift or delay can be calculated with respect to a reference signal. After the phase of each element is determined, the phase of the drive signal is determined to minimize the combined phase error between the element phase and the drive signal phase.

[0091] 7 provides a block diagram illustrating an exemplary implementation of a system for performing a diagnostic or therapeutic transcranial procedure. Control and processing hardware 500 is operatively connected to a transcranial headset 600, optionally via transducer driver electronics / circuitry 580.

[0092] The control and processing hardware 500 includes one or more processors 510 (e.g., CPU / microprocessors), a bus 505, memory 515 which may include random access memory (RAM) and / or read-only memory (ROM), a data acquisition interface 520, a display 525, external storage 530, one or more communication interfaces 535, a power supply 540, and one or more input / output devices and / or interfaces 545 (e.g., user input devices such as a speaker, keyboard, keypad, mouse, position-tracking stylus, position-tracking probe, footswitch, and / or microphone for capturing voice commands).

[0093] The volumetric image data 570 and transducer alignment data 575 may be stored in an external database or may be stored in the memory 515 or storage device 530 of the control and processing hardware 500 .

[0094] The control and processing hardware 500 may be programmed with programs, subroutines, applications, or modules containing executable instructions that, when executed by one or more processors 510, cause the system to perform one or more methods described in this disclosure. Such instructions may be stored, for example, in memory 515 and / or other storage devices.

[0095] In the illustrated exemplary embodiment, module 550 is used to calculate a set of phases to generate a reduced set of drive signals for each ultrasound module, and module 560 is used to control the switches of each ultrasound module to select the appropriate drive signal for each array element. Transducer control module 560 includes executable instructions for controlling the transducers of transcranial headset 600 to deliver energy to a target location or region of interest based on the alignment of the transducer position and orientation with the volumetric image data by transducer alignment data 575 and the delivery of drive signals provided to each module in the manner described above. For example, transcranial headset 600 can support multiple phased array transducers, and transducer control module 555 can control beamforming (transmit and / or receive) applied to deliver one or more focused energy beams to the region of interest based on the known position and orientation of the phased array transducers relative to the volumetric image data. The region of interest can be specified intraoperatively by a user (e.g., via a user interface controlled by control and processing hardware 500) or according to a pre-established surgical plan.

[0096] 7, any number of each component may be included within the control and processing hardware 500. For example, a computer typically includes several different data storage media. Furthermore, while the bus 505 is shown as a single connection between all of the components, it will be understood that the bus 505 may represent one or more circuits, devices, or communication channels linking two or more of the components. For example, in a personal computer, the bus 505 often includes or is a motherboard. The control and processing hardware 500 may include more or fewer components than those shown.

[0097] The control and processing hardware 500 may be implemented as one or more physical devices coupled to the processor 510 via one or more communication channels or interfaces. For example, the control and processing hardware 500 may be implemented using an application specific integrated circuit (ASIC). Alternatively, the control and processing hardware 500 may be implemented as a combination of hardware and software, where the software is loaded into the processor from memory or via a network connection.

[0098] Some aspects of the present disclosure may be embodied, at least in part, in software that, when executed on a computing system, transforms the computing system into a special-purpose computing system capable of performing the methods disclosed herein. That is, the present technology may be implemented in a computer system or other data processing system responsive to its processor, such as a microprocessor, executing sequences of instructions contained in a memory, such as ROM, volatile RAM, non-volatile memory, cache, magnetic and optical disks, or remote storage devices. Furthermore, the instructions may be downloaded to the computing device over a data network in the form of a compiled and linked version. Alternatively, the logic for performing the above-described processes may be implemented in additional computer- and / or machine-readable media, such as discrete hardware components, such as large-scale integrated circuits (LSIs), application-specific integrated circuits (ASICs), or firmware, such as electrically erasable programmable read-only memories (EEPROMs) and field-programmable gate arrays (FPGAs).

[0099] A computer-readable medium can be used to store software and data that, when executed by a data processing system, causes the system to perform various methods. The executable software and data can be stored in various locations, including, for example, ROM, volatile RAM, non-volatile memory, and / or cache. Portions of this software and / or data can be stored in any one of these storage devices. In general, a machine-readable medium includes any mechanism that provides (i.e., stores and / or transmits) information in a form accessible by a machine (e.g., a computer, a network device, a personal digital assistant, a manufacturing tool, any device having a set of one or more processors, etc.).

[0100] Examples of computer-readable media include, but are not limited to, recordable and non-recordable types of media such as volatile and non-volatile memory devices, read-only memory (ROM), random-access memory (RAM), flash memory devices, floppy and other removable disks, magnetic disk storage media, optical storage media (e.g., compact discs (CDs), digital versatile discs (DVDs), etc.), among others. Instructions may be embodied in digital and analog communication links for electrical, optical, acoustic, or other forms of propagated signals, such as carrier waves, infrared signals, digital signals, etc. As used herein, the phrases "computer-readable material" and "computer-readable storage medium" refer to all computer-readable media, excluding the transitory propagated signals themselves.

[0101] It will be appreciated that any of the exemplary embodiments of the present invention may be adapted for generating focused ultrasound waves for a wide range of clinical and research applications, including but not limited to intracranial treatments.

[0102] It should be understood that the specific embodiments described above are shown by way of example, and that these embodiments are susceptible to various modifications and alternative forms. It should also be understood that the claims are not limited to the particular forms disclosed, but rather are intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

Claims

1. 1. A phased array ultrasound system, comprising: support; a plurality of ultrasonic modules mechanically supported by the support, each ultrasonic module comprising a respective array of ultrasonic elements, each ultrasonic element in electrical communication with an output of a respective switch uniquely associated with the ultrasonic element; control and drive electronics that generate and deliver a respective set of drive signals to each ultrasonic module such that said set of drive signals is provided to each switch of said ultrasonic module; Equipped with the control and drive electronics can select any one drive signal of the set of drive signals to deliver to a given ultrasonic array element of a given ultrasonic module by controlling each switch to actuate the switch associated with the given ultrasonic array element; For each ultrasonic module of the plurality of ultrasonic modules: the number of drive signals in the set of drive signals provided to the ultrasonic module is less than the number of ultrasonic elements in the ultrasonic module; each drive signal of the set of drive signals having a respective phase, whereby the set of drive signals has an associated set of phase values; for at least two ultrasonic modules of the plurality of ultrasonic modules, the set of phase values ​​associated with the set of drive signals provided to the ultrasonic modules is a unique set of phase values ​​customized for the ultrasonic module; the control and drive electronics are configured to control each switch of each ultrasonic module, whereby for each switch, the drive signal provided to the ultrasonic element associated with the switch is from the set of drive signals provided to the switch and has a phase value closest to an ideal phase associated with the ultrasonic element to focus ultrasonic energy at a selected focal position; Phased array ultrasound system.

2. 2. The phased array ultrasonic system of claim 1, wherein the control and drive electronics are configured such that the unique set of phase values ​​associated with a given ultrasonic module is determined based on a set of ideal phases respectively associated with the array elements of the given ultrasonic module to focus ultrasonic energy at multiple locations within a selected region.

3. The phased array ultrasound system of claim 2 , wherein the control and drive electronics are configured such that the selected region is associated with a particular subject.

4. The phased array ultrasound system of claim 3 , wherein the control and drive electronics are configured such that the selected region spans a target volume associated with the particular subject.

5. 5. The phased array ultrasonic system of claim 1, wherein for at least two ultrasonic modules, the number of drive signals provided to each ultrasonic module depends on the span of the set of ideal phases.

6. 2. The phased array ultrasonic system of claim 1, wherein the control and drive electronics are configured such that the unique set of phase values ​​associated with a given ultrasonic module are determined based on a set of ideal phases respectively associated with the array elements of the given ultrasonic module to focus ultrasonic energy at the selected focal position.

7. 7. The phased array ultrasonic system of claim 6, wherein the control and drive electronics are configured such that the unique set of phase values ​​associated with a given ultrasonic module includes a maximum phase value, a minimum phase value, and at least one intermediate phase value between the maximum and minimum phase values, each intermediate phase value being within a phase range spanning a maximum and minimum ideal phase of the set of ideal phases associated with the given ultrasonic module.

8. 7. The phased array ultrasonic system of claim 6, wherein the control and drive electronics are configured such that the unique set of phase values ​​associated with a given ultrasonic module minimizes an aggregate phase error measure, the aggregate phase error measure being determined based on a phase error associated with each ultrasonic element of the given ultrasonic module, and each phase error being determined, for a given ultrasonic element of the given ultrasonic module, by calculating a difference between a phase value of a drive signal provided to the given ultrasonic element and an ideal phase value associated with the given ultrasonic element.

9. 9. The phased array ultrasonic system of claim 6, wherein for at least two ultrasonic modules, the number of drive signals provided to each ultrasonic module depends on the span of the set of ideal phases.

10. 10. The phased array ultrasonic system of claim 1, wherein the control and drive electronics are configured such that each drive signal is a pulsed drive signal for generating pulsed ultrasonic energy, and each set of drive signals is delivered to a respective ultrasonic module with a module-specific delay, the module-specific delay selected to facilitate time alignment of the pulsed ultrasonic energy from the ultrasonic module at a selected focal position.

11. The phased array ultrasound system of claim 1 , wherein the support is a conformal headset and the selected focal position is an intracranial focal position.

12. 12. The phased array ultrasonic system of claim 1, wherein for at least one ultrasonic module, each drive signal is provided to an equal number of ultrasonic elements.

13. 12. The phased array ultrasonic system of claim 1, wherein for at least one ultrasonic module, at least two drive signals are provided to different numbers of ultrasonic elements, respectively.

14. 12. The phased array ultrasonic system of claim 1, wherein at least two ultrasonic modules have different numbers of ultrasonic elements.

15. 12. The phased array ultrasound system of claim 1, wherein at least two ultrasound modules are supplied with a different number of drive signals.

16. 12. The phased array ultrasonic system of claim 1, wherein, for at least two ultrasonic modules, the number of drive signals provided to each ultrasonic module depends on the number of ultrasonic elements in the each ultrasonic module.

17. 17. The phased array ultrasonic system of claim 1, wherein for at least one module, the ratio of the number of ultrasonic elements to the number of drive signals is at least 16.

18. 18. The phased array ultrasound system of claim 1, wherein the switches are optically configurable and the control and drive electronics comprises a light source controllable to transmit an optical signal for configuring the switches to select an appropriate drive signal.

19. 19. The phased array ultrasound system of claim 1, wherein each unique set of phase values ​​is determined based on an acoustic model that characterizes spatial variations in acoustic properties of a tissue region to be insonified.

20. 1. A method of generating focused ultrasound waves from an ultrasound system comprising a support and a plurality of ultrasound modules mechanically supported by the support, each ultrasound module comprising a respective array of ultrasound elements, each ultrasound element electrically connected to an output of a respective switch uniquely associated with the ultrasound element, the method comprising: For each ultrasonic module: generating a set of drive signals for an ultrasonic module, each drive signal having a respective phase value, wherein the number of drive signals in the set of drive signals provided to the ultrasonic module is less than the number of ultrasonic elements in the ultrasonic module; providing the set of drive signals to each switch of the ultrasonic module; controlling the switches of the ultrasound module so that the drive signal provided to a given array element of the ultrasound module is a drive signal from the set of drive signals and has a phase value that is closest to an ideal phase value associated with the array element, so as to focus ultrasound energy at a selected focal position for the given array element of the ultrasound module; and For at least two ultrasonic modules of the plurality of ultrasonic modules, the set of phase values ​​associated with the set of drive signals provided to the ultrasonic modules is a unique set of phase values ​​customized for the ultrasonic module. method.

21. 21. The method of claim 20, wherein the unique set of phase values ​​associated with a given ultrasound module is determined based on a set of ideal phases respectively associated with the array elements of the given ultrasound module to focus ultrasound energy at multiple locations within a selected region.

22. 22. The method of claim 21, wherein the selected region is associated with a particular subject.

23. 23. The method of claim 22, wherein the selected region spans a target volume associated with the particular subject.

24. 21. The method of claim 20, wherein the unique set of phase values ​​associated with a given ultrasound module is determined based on a set of ideal phases respectively associated with the array elements of the given ultrasound module to focus ultrasound energy at the selected focal position.

25. 22. The method of claim 21, wherein the unique set of phase values ​​associated with a given ultrasonic module includes a maximum phase value, a minimum phase value, and at least one intermediate phase value between the maximum and minimum phase values, each intermediate phase value being within a phase range spanning a maximum ideal phase and a minimum ideal phase of the set of ideal phases associated with the given ultrasonic module.

26. 22. The method of claim 21, wherein the unique set of phase values ​​associated with a given ultrasonic module minimizes an aggregate phase error measure, the aggregate phase error measure being determined based on a phase error associated with each ultrasonic element of the given ultrasonic module, and each phase error being determined, for a given ultrasonic element of the given ultrasonic module, by calculating a difference between a phase value of a drive signal provided to the given ultrasonic element and an ideal phase value associated with the given ultrasonic element.

27. 27. The method of any one of claims 20 to 26, wherein each drive signal is a pulsed drive signal that generates pulsed ultrasonic energy, and each set of drive signals is delivered to a respective ultrasonic module with a module-specific delay, and each module-specific delay is selected to facilitate time alignment of the pulsed ultrasonic energy from the ultrasonic module at a selected focal position.

28. 28. The method of any one of claims 20 to 27, wherein the support is a conformal headset and the selected focal position is an intracranial focal position.

29. 29. The method of any one of claims 20 to 28, wherein each unique set of phase values ​​is determined based on an acoustic model that characterizes the spatial variation of acoustic properties of the tissue region to be insonified.

30. 1. A phased array ultrasound system, comprising: an array of ultrasonic elements, each ultrasonic element electrically connected to an output of a respective switch uniquely associated with said ultrasonic element; control and drive electronics configured to generate and transmit a set of drive signals and transmit said set of drive signals to each switch; Equipped with the control and drive electronics can control each switch to select which one of the set of drive signals to deliver to a given ultrasonic array element by activating the switch associated with the given ultrasonic array element; the number of drive signals in the set of drive signals is less than the number of ultrasonic elements in the array; each drive signal of the set of drive signals having a respective phase, whereby the set of drive signals has an associated set of phase values, the set of phase values ​​being determined based on a set of ideal phases respectively associated with the array elements of the array to focus ultrasonic energy at one or more locations; the control and drive electronics are configured to control each switch, and the drive signal provided to the ultrasonic element associated with the switch is from a set of drive signals provided to the switch and is the drive signal having a phase value closest to an ideal phase associated with the ultrasonic element at a selected focal position; Phased array ultrasound system.

31. 1. A method for generating focused ultrasound waves from an array of ultrasound elements, each ultrasound element electrically connected to an output of a respective switch uniquely associated with said ultrasound element, said method comprising: generating a set of drive signals, each drive signal having a respective phase value, whereby the set of drive signals has an associated set of phase values, the number of drive signals in the set of drive signals being less than the number of ultrasonic elements in the array of ultrasonic elements, the set of phase values ​​being determined based on a set of ideal phases respectively associated with array elements of the array to focus ultrasonic energy at one or more locations; providing said set of drive signals to each switch; controlling the switch such that the drive signal provided to a given array element is a drive signal from the set of drive signals and has a phase value that is closest to an ideal phase value associated with the array element to focus ultrasound energy at a selected focal position for the given array element; A method having the following.

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