Patent Publication Number: US-2021161509-A1

Title: Systems and methods for real-time tracking of a target tissue using imaging before and during therapy delivery

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/075,487, filed on Nov. 5, 2014, pending, the entire disclosure of the above application is expressly incorporated by reference herein. 
     This application is related to international PCT patent application serial No. PCT/US2014/022141, titled “TRANSDUCERS, SYSTEMS, AND MANUFACTURING TECHNIQUES FOR FOCUSED ULTRASOUND THERAPIES”, filed on Mar. 7, 2014, which is herein incorporated by reference in its entirety. 
    
    
     INCORPORATION BY REFERENCE 
     All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety, as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     This invention relates generally to the imaging field, and more specifically to a new and useful system and method for real-time tracking of a target tissue using imaging before and during therapy delivery. 
     BACKGROUND 
     Therapeutic energy delivery from a distance involves transmission of energy waves to affect a target tissue inside a patient&#39;s body. Therapeutic delivery of ultrasound waves has been used in a wide variety of therapeutic interventions, including lithotripsy, drug delivery, cancer therapy, thrombolysis, and tissue ablation. Non-invasive delivery of focused energy may allow for more efficient delivery of energy to the target tissue, improved cost effectiveness of treatment, minimized trauma to the patient&#39;s body, and improved recovery time. 
     Delivering energy over a distance requires targeting accuracy and technological flexibility while minimizing invasiveness into the patient. However, current methods fail to adequately track the target tissue motion while concurrently delivering the energy or therapy. A tissue in the body moves relative to the energy-delivering source from either the unintended patient body motion or the internal organs&#39; motion due to heartbeat, breathing, blood flow, or other physiological functions. Current methods stop delivering the energy or therapy when the tissue moves out of focus or visibility due, at least, to breathing or shadows and reinitiates energy or therapy delivery when the tissue reemerges. The stopping and starting of therapy or energy delivery can have unintended consequences for the patient, such as variable dosing, uneven or insufficient therapy delivery to the target tissue, and prolonged procedure times. 
     Conventional ultrasound systems for tracking a targeted soft tissue motion have a much lower signal-to-noise ratio. Further, the shape of a target image can change more as it moves within the image because of ultrasound beam scan orientation, tissue deformation, ultrasound signal distortion and other factors. Controlling these factors is desirable for effective and accurate therapeutic energy delivering to the target tissue. Since soft tissue deforms at a macroscopic level, conventional tracking systems cannot adequately track such tissue deformation and motion. Further, tracking and energy delivery will halt when a conventional system loses the target tissue, due to, for example, rib shadows or deep breaths that move the target out of sight. This happens regularly in conventional systems. Conventional systems are not configured to deal with these motions, and even more importantly they are not configured to properly recover tracking once the image reappears, requiring user input to relocate the lost target tissue in the image. 
     Thus, there is a need for a new and useful system and method for tracking a target tissue using imaging before and during therapy delivery. In particular, there is a need for new and useful systems and methods configured to accommodate when tissue moves out of focus or visibility, and even more importantly configured to automatically recover tracking when the image reappears. This invention provides such a new and useful system and method. 
     SUMMARY 
     A system for identifying at least one anatomical structure and tracking a motion of the at least one anatomical structure using imaging before and during delivery of a therapy to a patient, includes: an imaging module configured to identify a location and a feature of a region of the anatomical structure in an image, wherein the imaging module comprises a tracker, a detector, and an integrator; and a therapy module comprising an ultrasound treatment transducer configured to deliver the therapy to a target tissue in the patient. 
     Optionally, the imaging module is configured to, in real-time, track the anatomical structure using a feature identification technique. 
     Optionally, the imaging module is configured to use a histogram of the anatomical structure in the image, or a feature matching technique. 
     Optionally, the imaging module is configured to identify a location of the target tissue to be treated by the therapy module. 
     Optionally, the tracker is configured to identify a new location or a new feature of the region of the anatomical structure in response to a change in the location and the feature of the region of the anatomical structure. 
     Optionally, the detector is configured to identify a shape, a location, and a feature of the region of the anatomical structure. 
     Optionally, the tracker, detector, and integrator are implemented in graphics processor unit (GPU), field-programmable gate array (FPGA) or digital signal processor (DSP) or any other units containing computation capabilities. 
     Optionally, the therapy module is configured to function concurrently with the imaging module. 
     Optionally, the therapy module is configured to deliver therapy to the target tissue despite a change in the location or the feature of the region of the anatomical structure. 
     Optionally, the anatomical structure comprises the target tissue. 
     Optionally, at least one of breathing, blood flow, conscious movement, or unconscious movement of the patient changes the location and/or the feature of the region of the anatomical structure. 
     Optionally, the imaging module is configured to identify the location and the feature of the region of the anatomical structure in less than 1 second. 
     Optionally, the imaging module is configured to identify the location and the feature of the region of the anatomical structure in less than 5 milliseconds. 
     Optionally, the target tissue comprises a renal artery. 
     Optionally, the ultrasound treatment transducer is configured to provide renal denervation. 
     Optionally, the imaging module is configured to track the region of the anatomical structure is using a B-mode image, Harmonic Imaging, or 3D ultrasound imaging. 
     Optionally, the imaging module is configured to track the region of the anatomical structure using a color Doppler image, a color power Doppler image, or a directional color power Doppler mode image. 
     Optionally, the system further includes a filter, wherein the filter is configured to reduce noise in the image, such that the imaging module can determine the location and the feature of the region of the anatomical structure in the image. 
     Optionally, the filter is configured to provide a filtered image that is visible to the tracker, the detector, or both the tracker and detector. 
     Optionally, the system further includes a user interface for allowing a user to choose between viewing the filtered image or an unfiltered image. 
     Optionally, the location is an x and y coordinate. 
     Optionally, the location is an x, y, and z coordinate. 
     Optionally, the image is an ultrasound image. 
     Optionally, the integrator is configured to integrate results from the tracker and detector and direct the therapy module to deliver the therapy to the target tissue. 
     Optionally, the location is in a plane. 
     Optionally, the location is in a three-dimensional space. 
     Optionally, a plane of movement of the anatomical structure is substantially parallel to an imaging plane of the imaging module. 
     Optionally, the feature includes one or more of a characteristic, intensity, density, contrast, and shape of the region of the anatomical structure. 
     Optionally, the imaging module and the therapy module are configured to function consecutively using an interleaving mechanism. 
     Optionally, the imaging module and the therapy module are configured to function concurrently using a continuous mechanism. 
     Optionally, the therapy module is configured to predict a future location or a future feature of the target tissue and to deliver the therapy to the target tissue when the target tissue reaches the future location or the future feature. 
     Optionally, the therapy module is configured to provide lithotripsy. 
     Optionally, the lithotripsy comprises treatment of a kidney stone, gallstone, bile duct stone, or ureter stone. 
     Optionally, the tracker comprises a short-term detector. 
     Optionally, the detector comprises a long-term detector. 
     A system for tracking a renal artery during delivery of an ultrasound therapy to a patient, includes: an imaging module configured to identify a location and a feature of a region of an anatomical structure in an ultrasound image, wherein the imaging module comprises a tracker, a detector, and an integrator; and a therapy module comprising an ultrasound treatment transducer configured to deliver the ultrasound therapy to the renal artery, wherein the ultrasound treatment transducer is configured to be mechanically moved and/or electronically controlled. 
     Optionally, the ultrasound treatment transducer is configured to be moved by a motion control mechanism to move the ultrasound treatment transducer. 
     Optionally, the ultrasound treatment transducer comprises a full circular annular phased array. 
     Optionally, the ultrasound treatment transducer comprises a partial circular annular phased array. 
     Optionally, the ultrasound treatment transducer is configured to be directed and moved to guide therapeutic energy to the renal artery. 
     Optionally, the ultrasound treatment transducer comprises a two-dimensional array and is configured to move therapy focus by a three-dimensional electronic control mechanism to guide therapeutic energy to the renal artery. 
     Optionally, the ultrasound treatment transducer is configured to be moved by a mechanical control mechanism to guide therapeutic energy to the renal artery. 
     A method for imaging during delivery of a therapy, includes: acquiring an image of a body portion of a patient; identifying a region of an anatomical structure that has a relationship to a target tissue in the image; tracking a location and/or a feature of the region of the anatomical structure in the image; integrating results from the act of tracking; generating a template library to cover possible changes of the location and/or changes of the feature of the region of the anatomical structure; and delivering the therapy to the target tissue while tracking the region of the anatomical structure in the image. 
     Optionally, the method further includes continuously delivering therapy to the target tissue despite a change in one or more locations and features of the region of the anatomical structure. 
     Optionally, the act of tracking occurs in response to a change in the location or the feature of the region of the anatomical structure. 
     Optionally, the region of the anatomical structure comprises the target tissue. 
     Optionally, at least one of breathing, blood flow, conscious movement, or unconscious movement of the patient changes the location and/or the feature of the region of the anatomical structure. 
     Optionally, the region of the anatomical structure is undetectable by the imaging module as a result of at least one of breathing, blood flow, conscious movement, and unconscious movement. 
     Optionally, the method further includes stopping imaging of the body portion of the patient when the region of the anatomical structure is undetectable. 
     Optionally, the method further includes automatically re-detecting the region of the anatomical structure location or feature. 
     Optionally, the automatically recovering step further comprises automatically recovering the region of the anatomical structure location or feature by first determining a last known location or feature of the region of the anatomical structure in the image. 
     Optionally, the act of tracking occurs in less than 5 milliseconds. 
     Optionally, the act of delivering the therapy comprises denervating renal nerves surrounding the renal artery. 
     Optionally, the act of delivering comprises delivering ultrasound to the target tissue. 
     Optionally, the act of tracking comprises using a B-mode image, Harmonic Imaging, or 3D ultrasound imaging. 
     Optionally, the act of tracking comprises using a color Doppler image, a color power Doppler image, or a directional color power Doppler mode image. 
     Optionally, the act of tracking comprises using an image in B-mode, Harmonic mode, color Doppler mode, color power Doppler mode, a combination of the B-mode, the Harmonic mode and the color Doppler mode. 
     Optionally, the method further includes filtering the image to obtain a filtered image, such that the anatomical structure can be tracked in the filtered image. 
     Optionally, the method further includes determining if a pre-existing template matches a result from the act of tracking. 
     Optionally, the method further includes determining if a result from the act of tracking should be updated as a new template. 
     Optionally, a position of the target tissue is based on the pre-existing template and a new template. For example, averaging (e.g., weighted averaging, non-weighted averaging) may be performed using information in the pre-existing template and the new template to determine the position of the target tissue. 
     Optionally, the method further includes generating a new template when a pre-existing template does not match a result from the act of tracking, wherein the new template defines or indicates a location and a shape of the target tissue. 
     A method for treatment includes: acquiring with an imaging module an image of a body portion of a patient; identifying a region of an anatomical structure that has a relationship to a target tissue in the image; tracking a location and/or a feature of the region of the anatomical structure in the image; transforming a target position of the target tissue from an imaging space associated with the imaging module to a treatment space associated with a therapy module through one or more position sensors and a transmitter; and delivering a therapy with the therapy module to the target tissue while tracking the region of the anatomical structure. 
     Optionally, the one or more position sensors and the transmitter are configured to link a position of an imaging transducer of the imaging module to a position of an ultrasound treatment transducer of the therapy module. 
     Optionally, the one or more position sensors comprises a magnetic sensor, an optical sensor, an ultrasound sensor, or a mechanical position sensor. 
     Optionally, the one or more position sensors are mounted on an imaging transducer of the imaging module. 
     Optionally, the transmitter is mounted on an imaging transducer of the imaging module. 
     Optionally, the one or more position sensors are mounted on an ultrasound treatment transducer of the therapy module. 
     Optionally, the transmitter is mounted on an ultrasound treatment transducer of the therapy module. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a system for tracking a target tissue and delivering therapy to a target tissue, in accordance with a preferred embodiment; 
         FIG. 2  illustrates a tracking algorithm, in accordance with a preferred embodiment; 
         FIGS. 3A and 3B  illustrate images used for tracking and delivery of therapy to a target tissue, in accordance with a preferred embodiment; 
         FIG. 4  illustrates a flow chart for the functioning of a tracker, in accordance with a preferred embodiment; 
         FIG. 5  illustrates a tracker algorithm, in accordance with a preferred embodiment; 
         FIG. 6  illustrates a flow chart for the functioning of a detector, in accordance with a preferred embodiment; 
         FIG. 7  illustrates a detector algorithm, in accordance with a preferred embodiment; 
         FIG. 8  illustrates a flow chart for the functioning of an integrator, in accordance with a preferred embodiment; 
         FIGS. 9A and 9B  illustrate a system including a filter for tracking a target tissue and delivering therapy to a target tissue, in accordance with a preferred embodiment; 
         FIG. 10  illustrates a therapy module, in accordance with a preferred embodiment; 
         FIG. 11  illustrates a system including an imaging and therapy module, in accordance with a preferred embodiment; 
         FIGS. 12A and 12B  illustrate an interleaving and a continuous mechanism for imaging and therapy delivery, respectively, in accordance with first and second preferred embodiments; and 
         FIG. 13  illustrates a method of tracking a target tissue and delivering therapy to a target tissue, in accordance with a preferred embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following description of the preferred embodiments of the invention is not intended to limit the invention to these preferred embodiments, but rather to enable any person skilled in the art to make and use this invention. Disclosed herein are systems and methods for identifying at least one anatomical structure and tracking the motion of the at least one anatomical structure using imaging before and during delivery of a therapy to a patient. 
     Described herein are systems and methods for tracking an anatomical structure in a patient and delivering therapy to an anatomical structure. The structure receiving the delivered therapy from the system is the target tissue. In some embodiments, the system may function completely non-invasively. Alternatively, the system may additionally include catheterization or otherwise surgically manipulating the patient. The system may be used to track an anatomical structure, such as an organ, blood vessel, artery, bone, blood, or any other type of anatomical structure. For example, in some embodiments, the system may function to track a kidney or renal artery of a patient. Alternatively, the system may be used to track a region of an anatomical structure, such as a curved edge or surface, a more distal or proximal portion of an organ, blood flow through a vessel, a distinguishing feature of an organ, for example glomeruli of the kidney, or any other region of interest of an anatomical structure. In some embodiments, a feature of an anatomical structure may be tracked, such as a location, shape, intensity, contrast, density, or otherwise characteristic of the anatomical structure. The location of an anatomical structure may include an x, y coordinate or an x, y, z coordinate. Alternatively, the location of the anatomical structure may be tracked in a two-dimensional plane or in three-dimensional space. The tracked anatomical structure may be a different structure than the anatomical structure receiving therapy from the system, such that a change in location or feature of the anatomical structure indicates a change in position of the target tissue. Alternatively, the anatomical structure may be the same as the target tissue, such that the target tissue is the anatomical structure that is being tracked. In some embodiments, the tracked anatomical structure may be a kidney and the target tissue receiving therapy may be a renal artery. 
     In some embodiments, the system may deliver therapy via ultrasound, mechanical vibrations, electromagnetic waves, lasers, X-ray or any other type of non-invasive radiation therapy. The therapy may include renal denervation, kidney stone disruption, gallstone disruption, bile duct stone disruption, ureter stone disruption, or any other type of non-invasive therapy. 
     In general, an anatomical structure may be lost and/or move during tracking and/or while receiving therapy. For example, an anatomical structure may be lost due to a shadow from another organ or bone structure, for example the rib cage. Alternatively or additionally, an anatomical structure may move due to breathing, blood flow, conscious movement, or unconscious movement of the patient during the procedure. In some instances, the region of the anatomical structure may become undetectable by the system as a result of breathing, blood flow, conscious movement, or unconscious movement of the patient. For example, an anatomical structure may move approximately 2 cm/second. In some instances, the anatomical structure may move substantially in a plane parallel to the plane of the system, or principal plane. Alternatively, the anatomical structure may move perpendicularly or variably relative to the system. As described herein, the system is configured to track a region of an anatomical structure despite shadows or deep breathing by a patient that moves an anatomical structure out of sight. 
     In some embodiments, the system may utilize an imaging module to locate the target tissue and track the position and/or movements of the target tissue, such that the therapy module can maintain its focus on the target tissue during the treatment process. In some embodiments, the imaging information may be used to confirm that the focus of the therapy module is properly positioned over the treatment region. The system then calculates the treatment parameter, such as dosing of ultrasound energy to be applied to the treatment region. For example the physician may enter the desired dosing level for a particular treatment. The system may also take into account other parameters, such as the distance of the target region from the therapy module, and calculate the appropriate ultrasound energy to apply to achieve the desired dosing at the target region. A particular treatment plan, such as a specific treatment pattern (e.g., energizing multiple spots within a treatment area), and a specific dosing routine (e.g., spreading a dose into multiple quantized delivery over a finite period of time to achieve the desired dose) may be selected. The system may then implement the treatment plan, and ultrasound energy may be delivered to the treatment region based on the treatment plan. In some embodiments, the treatment plan includes sequential lesions offset from the blood flow of a vessel and within 5 mm of one another. In another embodiment, the treatment plan includes sequential lesions offset from the blood flow and within 1 mm of each other. In another embodiment, the sequential lesions do not have an offset from one another and sequential lesions are applied atop one another in substantially the same position. 
       FIG. 1  illustrates a system  100  for tracking a region of an anatomical structure and delivering therapy to a target tissue, in accordance with a preferred embodiment. The system according to  FIG. 1  preferably functions to image one or more anatomical structures, track a location or a feature of the anatomical structure, and delivery therapy to a target tissue. As shown in  FIG. 1 , a system  100  for identifying at least one anatomical structure and tracking the motion of the at least one anatomical structure using imaging before, during, or after delivery of a therapy to a patient includes an imaging module  101  and a therapy module  102 . The imaging module  101  may be configured to acquire an image, identify one or more locations and/or features of an anatomical structure in the image, and/or track a location and/or feature of the anatomical structure within the image. The therapy module  102  of the system  100  may be configured to deliver therapy to a target tissue 
     In some embodiments, the therapy module  102  may include a therapy energy delivering subsystem  107 , which functions to generate controlled electrical energy to the ultrasound treatment transducer  108 . In some embodiments, the ultrasound treatment transducer  108  transmits the ultrasound energy into the targeted tissue structure in a human body. In some embodiments, the ultrasound treatment transducer  108  may be a full circular annular phased array transmitting the focused ultrasound energy along the acoustic axis in depth direction into the targeted tissue structure in a human body. In other embodiments, the ultrasound treatment transducer  108  may be a section of full (e.g., partial) circular annular phased array transmitting the focused ultrasound energy along the acoustic axis in depth direction into the targeted tissue structure in a human body. For example, the transducer may have a pie shape so that the shape is less than a full circular shape. In some embodiments, the therapy module  102  may include a tip/tilt motion control unit  109  that adjusts the ultrasound treatment transducer rotation in tip and tilt directions to follow the targeted tissue motion. In other embodiments, the following of the targeted tissue motion may be accomplished by electronic control of the phasing of the ultrasound elements in the ultrasound treatment transducer, thereby obviating the need to mechanically move the ultrasound treatment transducer. In further embodiments, the control of the ultrasound energy focus may be accomplished using both electronic phasing control of ultrasound elements in the ultrasound transducer  108  and mechanical control of the movement of the ultrasound transducer  108  by the therapy module  102 . In some cases, such technique may allow control of ultrasound energy focus at any position within a huge treatment volume in 3D space. In some embodiments, the therapy module  102  may further include a transmitter and/or one or more position sensors of a 3D position system  110 . 
     In some embodiments, the imaging module  101  may include an image acquisition subsystem  103  that functions to acquire an image. In some embodiments, the image acquisition subsystem  103  may use ultrasound to acquire images of a region of an anatomical structure. In some embodiments, the imaging module  101  may further include an image tracking system  104  that functions to track a location and/or feature of an anatomical structure within the image acquired by the image acquisition subsystem  103 . In some embodiments, the imaging module  101  may include an ultrasound imaging transducer  105  that transmits the ultrasound signals into the human body and receives the reflected signal from the tissue structures. In some embodiments, the imaging module  101  may further include position sensors  106  that are attached to the imaging transducer  105  to acquire the position of the imaging transducer  105  in 3D space and feed the position information to the imaging tracking subsystem  104 . In some embodiments, the imaging transducer  105  may be linear, curved linear, phased, annular, or other types of imaging arrays that acquire an imaging plane inside a human body. In some embodiments, the imaging transducer  105  may be a two-dimensional array that acquires 3D ultrasound images inside a human body. 
     In some embodiments, the 3D position system determines the position of the ultrasound treatment transducer  108  and the relationship of the positions between the imaging transducer  105  and ultrasound treatment transducer  108 . In some embodiments, an imaging ultrasound transducer  105  may be included near the therapy module  102 , such that images may be acquired of the region of the anatomical structure being targeted, tracked, and treated as will be described below. 
     In some embodiments, the imaging module may acquire an ultrasound image. For example the imaging module may use echoes of ultrasound pulses to delineate objects or areas of different density in the body. A frequency range used may be between 0.5 to 18 megahertz or up to 50 or 100 megahertz. Alternatively, x-ray, computed tomography, magnetic resonance, or any other type of imaging modality, optical or otherwise, may be used. In some embodiments, the imaging of an anatomical structure may be acquired in a B-mode image, Harmonic image, a color Doppler image, a color power Doppler image, a directional color power Doppler mode image, any other type of image, or any combination of two or more of the foregoing. For example, in a B-mode image and/or Harmonic image, the system may image a two-dimensional cross-section of the tissue. Alternatively or additionally, the system may utilize color Doppler imaging, an imaging technique that combines anatomical information derived using ultrasonic pulse-echo techniques with velocity information derived using ultrasonic Doppler techniques to generate color-coded maps of tissue velocity superimposed on grey-scale images of tissue anatomy. Further, color power Doppler imaging has increased intensity and the added benefit of depicting flow in small vessels. 
     In some embodiments, the imaging module  101  may function to identify a position of a region of an anatomical structure, such that the therapy module  102  may deliver therapy in a substantially continuous manner to the target tissue. The imaging module  101  may rapidly identify the position of the target tissue such that the therapy module  102  may then rapidly deliver therapy to the target tissue. In an interleaving pattern, the position may be identified, followed by therapy delivery, followed by position identification, and so on. This interleaving pattern of the imaging module and therapy module may occur in rapid, repetitive succession such that therapy is delivered substantially continuously. The rapid, repetitive succession is required, such that the target tissue may be tracked substantially continuously and the therapy may be delivered substantially continuously. 
     In some embodiments, the imaging module  101  may function rapidly, such that a dose of therapy may be delivered substantially continuously to the target tissue without significant delay between identifying a position of the target tissue and delivering therapy to the target tissue or between subsequent doses of therapy to the target tissue. For example, the imaging module  101  may identify one or more locations and/or features of the region of the anatomical structure in less than 10 seconds, 5 seconds, 3 seconds, 2 seconds, or 1 second. Alternatively, the imaging module may identify one or more locations and/or features of the region of the anatomical structure in less than 1000 milliseconds, 750 milliseconds, 500 milliseconds, 250 milliseconds, 100 milliseconds, 75 milliseconds, 50 milliseconds, 25 milliseconds, 10 milliseconds, 5 milliseconds, or 1 millisecond. In some embodiments, the imaging module may use a frame rate of greater than or equal to 20 Hz. Alternatively, the imaging module may use a frame rate of less than 20 Hz. 
     Returning to  FIG. 1 , in some embodiments, the image tracking subsystem  104  of imaging module  101  includes a tracker and a detector. Both the tracker and detector are computer algorithms configured to identify and track a shape, location, and/or feature of a region of an anatomical structure in an image by searching within a region of interest in the image for a shape, location, and/or feature of the region of the anatomical structure. As described below in further detail, the imaging module  101  may weigh results from the tracker and detector differentially, such that in some instances only the tracker results may be used or, alternatively, only the detector results or both. In some embodiments, the tracker and detector may each independently identify and track a shape, location, and/or feature of a region of an anatomical structure in an image. The tracker and detector may identify motion of a region of an anatomical structure and compensate for the motion by adjusting the focal point, such that therapy may be delivered substantially continuously to a target tissue. In some embodiments, a system may use both a tracker and detector to identify and track a region of an anatomical structure in an ultrasound image. The tracker and the detector complement each other, increase robustness of the system, and compensate for non-uniformity of ultrasound waves (as compared to imaging with light) in their interactions with an object or tissue being imaged. 
     In some embodiments, the tracking capabilities of the tracker and detector may be combined into one algorithm, negating the need for a separate tracker and detector. In some embodiments, results from the tracker and detector may be compared to templates, which identify a previous shape, location, and/or feature of the region of the anatomical structure. For example, the tracker may be a short-term detector in that the results are compared to several previous image (I n-p , I n-p-1 , . . . I n-3 , I n-2 , I n-1 ) and use weighted function to obtain the final position. In some embodiments, the tracker will first look for change near the previous location (i.e. previous image (I n-1 ) rather than looking throughout the entire image. Further for example, the detector may be a long-term detector in that the results are compared to more than one template (i.e. a template pool) from any number of previous images. In some embodiments, the long-term template management samples breathing cycles. In general, the combination of the complimentary tracker and detector will enable the system to compensate automatically, without user intervention, if the target becomes lost or unfocused. Alternatively, any quantity and/or type of trackers and/or detectors may be used. In some embodiments, the system may include additional trackers and/or detectors such that the additional trackers and/or detectors complement the existing trackers and detectors for tracking a region of an anatomical structure. In some embodiments, the multiple complementary trackers and/or detectors may lead to an increased computation time and/or memory requirements, however the robustness of the system will also improve. In some embodiments, the system  100  further includes an integrator. The integrator is an algorithm configured to compare and/or integrate the results from tracker and detector of the image tracking subsystem of the imaging module  101  and direct the therapy module  102  to deliver the therapy to the target tissue. 
     The tracker and detector are algorithms for determining a location and/or feature of a region of an anatomical structure. In some embodiments, as shown in  FIG. 2 , a feature histogram algorithm may be used. Feature histogram describes the two-dimensional spatial distribution of the featured pixels in a defined area or analysis region  201 . As shown in  FIG. 2 , the analysis region  201  may be equally divided into several smaller regions. The analysis region  201  containing 6 by 6 pixels, as shown in  FIG. 2 , is subdivided into 4 sub-regions  202 , which contains 3 by 3 pixels  203 . However, it should be understood that any number of pixels in analysis region  201  may be used, for example less than 36 pixels or more than 36 pixels. For example, a 5×5, 75×75, 100×100, 500×500, or 1000×1000 pixels, or anything above, below or in-between may be utilized. 
     In some embodiments, as shown in  FIG. 2 , a pixel  203  of an anatomical structure may be identified, for example by contrast, pixel density, or intensity, in the analysis region  201 , denoted by an “x” in the pixel  203 . Each “x” or pixel feature may be totaled for each sub-region, resulting in a 2 by 2 feature histogram  204  of region  201 . The 2 by 2 feature histogram  204  is further normalized into a 2 by 2-normalized feature histogram  205 . The distribution of the feature histograms indicates a location or feature of the region of the anatomical structure. However, it should be understood that any number of histogram dimension can be used, for example 4 by 4, 8 by 8, 8 by 4, 4 by 8, 16 by 16, 16 by 8, 8 by 16, 32 by 32 or any other number. 
     In some embodiments, a first feature histogram indicating a first location or feature of a region of an anatomical structure may be compared to second feature histogram indicating a second location or feature of the region of the anatomical structure. In some embodiments, the first or second feature histogram may include a template from a previous image. The two histograms may be compared using equation (1) below, where H 1   ij  is the first feature histogram, H 2   ij  is the second feature histogram, N is the total number of bins in the x-direction of the 2D feature histogram, M is the total number of bins in the y-direction of the 2D feature histogram, and D is the distance between the two histograms between 0 and 1. When D=0, the two histograms are identical. Conversely, when D=1, the two histograms are the most different. 
     
       
         
           
             
               
                 
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     In some embodiments, alternative algorithms may be employed, such as sum squared difference, sum absolute difference, or normalized cross correlation (NCC). For example, in NCC, a position of the region of the anatomical structure is determined by a pixel-wise comparison of the current image with the template containing a previous position of the region of the anatomical structure. The search region in the template is shifted in discrete steps in the N and M directions, and then the comparison is calculated (i.e. subtracting the mean and dividing by the standard deviation at every step) over the template search area for each position. The position of the maximum NCC values indicates the position of the region of the anatomical structure in the current image. Alternatively, any other threshold NCC value (i.e. minimum) may be used. 
       FIGS. 3A and 3B  illustrate a region of an anatomical structure that is being tracked by two tracking boxes  302 ,  303  working on different tissue areas, in and around a region  301  that is viewable by a user. Each tracking box is associated with its own tracker, detector, and integrator. As shown in  FIG. 3 , two tracking boxes  302 ,  303  are used to increase the robustness and fidelity of the system, such that both the first and second tracking boxes are tracking a similar region of the anatomical structure in each of the tracking boxes  302 ,  303 . Tracking is not completely lost and therapy is not stopped unless both boxes lose tracking. For example, if the first tracking box (associated with tracker, detector, and integrator) becomes lost and/or is unable to find the region of the anatomical structure, the second tracking box (associated with tracker, detector, and integrator) will continue tracking the region of the anatomical structure and therapy delivery will continue and vice versa. 
     In this example, the tracking boxes are tracking a location or feature of a region of an anatomical structure in two images, at opposite ends of a breathing cycle, using a feature histogram algorithm, as described above. For example, a beginning of a breathing cycle is shown in  FIG. 3A  and an end of a breathing cycle is shown in  FIG. 3B . The crosshairs  304  indicate a target region or tissue for receiving therapy. As shown in  FIG. 3 , the target tissue (e.g. renal artery) receiving therapy is distinct from the regions of the anatomical structure (e.g. tissue) that is being tracked by the tracking boxes. In some embodiments, the search region may be any size, for example 361 pixels by 420 pixels. Alternatively, the search region may be larger than 361 pixels by 420 pixels or less than 361 pixels by 420 pixels. The tracking boxes  302 ,  303  may be any size, for example 64×64 pixels. Alternatively, the tracking boxes may be less than 64×64 pixels or greater than 64×64 pixels. In some embodiments, a user may select the tracking box size. Alternatively, the tracking box size may be selected automatically by the system. Alternatively, only one tracking box or more than two tracking boxes may be used. In some embodiments, the system may include additional tracking boxes to add redundancy to the system. In some embodiments, the multiple complementary trackers and/or detectors may lead to an increased computation time and/or memory requirements, however the robustness of the system will also improve. 
     In some embodiments, the tracking performed by the first and second tracking boxes may occur with an accuracy of root-mean-square (RMS) error of less than or equal to 2 mm. Alternatively, the RMS error may be more than 2 mm, but still within a suitable accuracy. In some embodiments where two tracking boxes are used, if both the tracking boxes  302 ,  303  are lost, the tracking boxes  302 ,  303  may recover at the same time and maintain the same relative position with error within less than or equal to 40 pixels. Alternatively, the error may be within more than 40 pixels. Further, in some embodiments, if the region of the anatomical structure moves outside of the image, the tracker and detector will cease to track the region of the anatomical structure. 
     In some embodiments, as shown in  FIG. 4 , a tracker may function as a short-term detector, as described above. The tracker may compare a feature histogram of a current location or feature of a region of an anatomical structure in a current image (I n ) to a template. In some embodiments, the template may be a feature histogram of a previous location or feature of the region of the anatomical structure in a previous image (I n-1 ). In some embodiments, the tracker may search for a change in a region of the anatomical structure near a previous location of the region of the anatomical structure in the template instead of searching an entire template. The two feature histograms are compared, for example using equation (1), and the minimum distance D between the two feature histograms may be determined and the x, y coordinates of the point of the minimum distance D may be identified, as shown in  FIG. 4 . Alternatively, a maximum distance D or any other threshold may be used when comparing two or more feature histograms. 
     As shown in  FIG. 5 , within the search region  501 , the tracker tracks a possible current location or feature  502  of a region of the anatomical structure in the current image (I n ). The previous location or feature (with M, N coordinates) of the region of the anatomical structure from image (I n-1 ) is a template  503 , as described above. In some embodiments, the tracker may search for a change in a region of the anatomical structure near a previous location of the region of the anatomical structure instead of searching the entire image. The distance between the feature histograms of the possible current location or feature  502  and the previous location or feature  503  of the region of the anatomical structure is calculated. Each of the distances may be represented by value D, such that the minimum D value and the position of the minimum D value indicate a best match between a current location or feature and a previous location or feature of the region of the anatomical structure in the template. 
     As shown in  FIGS. 6 and 7 , within the search region  701 , the detector may function as a long-term detector, as described above. The detector may detect a possible current location or feature of a region of the anatomical structure in a current image (I n ). The feature histogram of the possible current location or feature  702  in a current image I n  is compared to a template pool  704  comprising feature histograms for one or more templates of previous locations and/or features, for example  703 , of the region of the anatomical structure in previous images (I n-1 ). For example, a template pool  704  may include a plurality of templates. As one example, the template pool  704  may include 64 templates. The feature histograms of the possible current location or feature  702  of a region of the anatomical structure are compared to the feature histograms of the one or more templates, for example  703 , through calculating the D value. The template corresponding to the minimum D value and the position of the minimum D value indicates a best match between a current location or feature  702  and the template from the template pool  704 , identifying the location or feature as the region of the anatomical structure  701 , as shown in  FIG. 7 . In some embodiments, a maximum Normalized Cross Correlation (NCC) value may correspond to a best match between a current location or feature and the template from the template pool, which could replace the D value as described above. 
     In some embodiments, the feature histogram of the current image is compared to all templates in the template pool. Alternatively, the feature histogram of the current image may be compared to a subset of the template pool. In some embodiments, all templates search in their own search regions and the region of the anatomical structure is at the position, which gives the maximum (i.e. NCC value) or minimum value (i.e. sum squared difference value) in all search regions of the templates. 
       FIG. 8  illustrates an integrator flow chart. In some embodiments, as shown in  FIG. 8 , an integrator is an algorithm that compares the tracking results from the tracker and detector and determines (1) if the results from the tracker or detector should be used in determining a current location or feature of the region of the anatomical structure and (2) if the results from the tracker and detector should be added as a template to the template pool. In some embodiments, the integrator weighs the results of the detector more heavily. As shown in  FIG. 8 , if the results from the detector match with a key template, which is a template sampled throughout the motion cycles, then the integrator will use the detector results  802 . Otherwise, if the distance value D determined by the detector is less than the distance value D determined by the tracker  803 , the integrator will use the results from the detector  804 , such that the smaller distance value D from the detector more accurately defines the feature histogram of the location or feature. Alternatively, if the distance value D determined by the detector is more than the distance value D determine by the tracker, then the integrator further evaluates the results from the tracker  805 . If the distance value D is greater than a predetermined threshold or if the distance of the current location to the closest template location is greater than a predefined pixel distance (L), for example 3√{square root over (2)} or any other distance, the feature histogram denoted by distance value D will be updated as a template and maintained as part of the template pool  807 . In some embodiments, if the location of a current feature is a predefined distance (L) from all other templates in the pool, then the current feature will be saved as a “key” template. Any of the above integrations performed by the integrator may be sent to the therapy module, such that an x, y, z coordinate of the current location may be sent to the therapy module and the therapy module may deliver therapy to the target tissue, as shown in  FIG. 8 . In some embodiments, the time between the therapy module receiving instructions and delivering therapy is less than or equal to 50, 40, 30, 20, 10, 5, or 1 milliseconds. Alternatively, the time between receiving instructions and delivering therapy may be more than 50 milliseconds. 
     In some embodiments, as shown in  FIG. 9A , a system  900  for tracking a region of an anatomical structure and delivering therapy to a target tissue may further include a filter  901 . The filter may use an algorithm to reduce noise in the image (I n ), such that the imaging module  902  may determine one or more locations and/or features of the region of the anatomical structure in the image (I n ). In some embodiments, the noise may include speckle, multiple coherent reflections from the environment surrounding the region of the anatomical structure or target tissue, or any other type of noise. In some embodiments, the filtered image may be visible only to one of the tracker or detector. Alternatively, both the tracker and detector may use the filtered image. In some embodiments, a user of the system  900  may select between viewing the filtered image or an unfiltered image. 
     In some embodiments, as shown in  FIG. 9B , a filter may use a simple moving average filter to remove noise in an image (I n ). As shown in  FIG. 9B , each region  903  of the image may be identified (i n ) and the average intensity of the pixels in each region may be determined. Equation (2) may be used to smooth the image, such that y[i] equals the smoothed pixel intensity, M equals the number of regions  903  in the average, i equals the location of smoothed pixel, and j equals the index within the region. Alternatively, any other type of filtering equation may be used. 
     
       
         
           
             
               
                 
                   
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     In some embodiments, where the integrator integrated the results from the tracker and detector, as described above with respect to  FIG. 8 , the therapy module may receive a current target tissue location and a distance to the current target tissue location from the integrator. In some embodiments, the therapy module  1000  may include one or more ultrasound transducers  1001 ,  1002 , as shown in  FIG. 10 . The therapy module  1000  may include a phased or fixed array of ultrasound transducers  1002  for delivering therapy to the target tissue. Further, in some embodiments, as shown in  FIG. 10 , the therapy module may include a second phased or fixed array of ultrasound transducers  1001  for acquiring images of the region of the anatomical structure. The region of the anatomical structure may then be tracked in the image by the tracker and detector, as described above. As shown in  FIG. 11 , the therapy module  1000  may be integrated into a patient platform  1030 , such that the therapy module  1000  is positioned in a cavity  1010  of the patient platform  1030  while maintaining access to a patient lying on the patient platform  1030 . In some embodiments, the imaging module  1020  may be in the same room and/or electrically connected to the patient platform  1030  and/or the therapy module  1000 . Alternatively, the imaging module  1020  may be in communication with the therapy module  1000  through Bluetooth, Wi-Fi, or any other type of connection. Other features and aspects of the system  1050  of  FIG. 11  are disclosed in PCT Application Serial Number 2014/022141, which is herein incorporated by reference. 
     In some embodiments, the ultrasound transducer of the therapy module may be moved, repositioned, or otherwise relocated by a motion control mechanism. Alternatively, the ultrasound transducer of the therapy module may be directed and moved to guide therapeutic energy to the target tissue, for example by an applicator  1060 . In some embodiments, the ultrasound transducer of the therapy module may be moved by a three-dimensional electronic beam steering control mechanism to guide therapeutic energy to the target tissue. Alternatively, the ultrasound transducer of the therapy module may be moved by a mechanical control mechanism to guide therapeutic energy to the target tissue. 
     In some embodiments, as shown in  FIG. 12A , the imaging module and therapy module may function in rapid succession in an interleaving mechanism.  FIG. 12A  illustrates the interleaving pattern with solid arrows representing hard sync triggers and dashed arrows representing soft sync triggers. The interleaving pattern, as shown in  FIG. 12A , may continue until the prescribed dose of therapy has been delivered. In some embodiments, the therapy module will be re-targeted to a new lesion or position and the interleaving mechanism will resume. Alternatively, in some embodiments, the imaging module and therapy module may function simultaneously, such that therapy is continuously being delivered while the imaging module is transmitting tracker and detector results to the therapy module, as shown in  FIG. 12B . Alternatively or additionally, the therapy module may function using a predictive mechanism, such that the therapy module may predict a future position of the region of the anatomical structure that is being tracked by the imaging module from several previous target positions and move to that predicated position to deliver therapy. 
       FIG. 13  illustrates a method of tracking a target tissue and delivering therapy to a target tissue, in accordance with a preferred embodiment. As shown in  FIG. 13 , a method for imaging during delivery of a therapy of a preferred embodiment includes the steps of acquiring an image of a body portion of a patient S 100 ; identifying a region of an anatomical structure that has a relationship to a target tissue in the image S 110 ; tracking a location or feature of the region of the anatomical structure in the image S 120 ; integrating the results from the tracking S 130 ; generating a unique template library to cover possible changes of the one or more locations and features of the region of the anatomical structure S 140 ; determining if a pre-existing template matches a result from the tracking or if the result should be updated as a new template, wherein the pre-existing template and the new template define a position of the target tissue in the image S 150 ; and delivering the therapy to the target tissue while tracking the region of the anatomical structure in the image S 160 . In some embodiments, the method preferably functions to track a region of an anatomical structure, such that the position of the anatomical structure correlates with a position of a target tissue. The method may be used for delivering ultrasound to denervate a renal artery but, additionally or alternatively, can be used for any suitable applications, clinical or otherwise. For example, the method may be used to deliver ultrasound to a kidney, gallbladder, bile duct, or ureter to disrupt kidney, gallstones, bile duct stones, or ureter stones, respectively. 
     As shown in  FIG. 13 , step S 100  includes acquiring an image of a body portion of a patient. Step S 100  preferably functions to image a region of an anatomical structure of a patient, such that a location and/or feature of a region of the anatomical structure may correspond to a position of the target tissue for receiving therapy. As described above, the image may be acquired in B-mode, Harmonic image, color Doppler, color power Doppler, or directional color power Doppler mode image. In some embodiments, the imaging may be performed using ultrasound or any other type of imaging modality, optical or otherwise. 
     As shown in  FIG. 13 , step S 110  includes identifying a region of an anatomical structure that has a relationship to a target tissue in the image. Step S 110  preferably functions to identify a region of an anatomical structure that moves, deforms, or otherwise tracks in a similar manner as the target tissue, such that the anatomical structure may be tracked while the target tissue is receiving therapy. For example, if the target tissue moves 2 cm to the right in the image, the region of the anatomical structure being tracked should also move 2 cm to the right. In some embodiments, the target tissue is the anatomical structure being tracked. 
     As shown in  FIG. 13 , step S 120  includes tracking a location or feature of the region of the anatomical structure in the image. Step S 120  preferably functions to track a location or feature of a region of the anatomical structure using a tracker and detector, such that the therapy module may be notified of a change in location or feature of the target tissue. In some embodiments, step S 120  occurs in response to a change in location or feature of the region of the anatomical structure. 
     As shown in  FIG. 13 , step S 130  includes integrating the results from the tracking with the tracker and detector. Step S 130  preferably functions to determine if the results from the tracker and detector will be used and if a new template should be generated based on the results from the tracker and detector. For example, if the tracking results from the tracker and detector, respectively, match a key template, as described above, the integrator will use the detector results and instruct the therapy module to deliver therapy to the target tissue, such that a position of the target tissue is known by the integrator and transmitted to the therapy module. 
     As shown in  FIG. 13 , step S 140  includes generating a unique template library to cover possible changes of the one or more locations and features of the region of the anatomical structure. Step S 140  preferably functions to maintain a template pool of possible locations and/or features of the anatomical structure being tracked by the imaging module, such that the template pool was generated over time from previous images. Each result from the tracker and detector may be compared to the template pool to determine if 1) the result matches a template and thus the template can inform the therapy module as to the position of the target tissue or 2) the result does not match a template and a new template needs to be generated and thus the new template can inform the therapy module as to the position of the target tissue, as further recited in S 150 . 
     As shown in  FIG. 13 , step S 160  includes delivering the therapy to the target tissue while tracking the region of the anatomical structure in the image. Step S 160  preferably functions to deliver therapy to the target tissue while consistently aligning an orientation, position, or otherwise direction of the therapy module with the target tissue. The therapy module, as described herein, receives information from the imaging module that pertains to a position of the target tissue, such that the tracker and detector track a position of the target tissue by tracking a region of an anatomical structure. 
     In some embodiments, the method of  FIG. 13  further includes substantially continuously delivering therapy to the target tissue despite a change in one or more locations and features of the region of the anatomical structure. The therapy module may continue delivering therapy despite a change since the imaging module may alert, notify, or otherwise inform the therapy module of the change, and the therapy module may adjust accordingly. 
     In some embodiments, the method of  FIG. 13  further includes stopping the imaging of the region of the anatomical structure when the region of the anatomical structure is undetectable. For example, the anatomical structure may move perpendicularly away from the imaging plane, such that the region of the anatomical structure is undetectable. In some embodiments, the imaging module may automatically recover (e.g. without user intervention) the region of the anatomical structure location or feature, such that therapy delivery may resume. Further, automatically recovering the region of the anatomical structure location or feature may occur by first determining a last known location or feature of the region of the anatomical structure in the image (logic function). In some embodiments, the last known location or feature may correspond to a template from the template pool. 
     In some embodiments, the method of  FIG. 13  further includes filtering the image, such that the anatomical structure can be tracked in the filtered image. The image may be filtered using a moving average filter or any other type of filter. 
     In some embodiments, the method of  FIG. 13  further includes generating a new template when the pre-existing template does not match the tracking results, such that the new template corresponds to a position of the target tissue in the image. In some embodiments, the new template is assigned as the key template, as described above. In some embodiments, the new template may be generated by the integrator. 
     In some embodiments, the method of  FIG. 13  is implemented in a graphics processing unit (GPU), FPGA, and/or DSP to further reduce the computation time of the tracker, detector and integrator. 
     As described herein, a method for treatment includes: acquiring with an imaging module an image of a body portion of a patient; identifying a region of an anatomical structure that has a relationship to a target tissue in the image; tracking a location and/or a feature of the region of the anatomical structure in the image; transforming a target position of the target tissue from an imaging space associated with the imaging module to a treatment space associated with a therapy module through one or more position sensors and a transmitter; and delivering a therapy with the therapy module to the target tissue while tracking the region of the anatomical structure. In some embodiments, the act of transforming is performed to bring a target position of the target tissue (e.g., renal artery) in the imaging space (e.g., ultrasound imaging coordinate) to a transformed target position in the treatment space (e.g., therapeutic array coordinate). Various techniques may be employed to achieve such objective. For example, in some cases, a real-time electromagnetic tracking system with sub-millimeter and sub-degree accuracy may be used. The magnetic field sensor may be attached on the handle of the imaging transducer, and a magnetic field transmitter may be attached to the base of therapeutic treatment module. The magnetic field transmitter generates a magnetic field. When the magnetic sensor is placed inside controlled, varying magnetic fields generated from the transmitter, voltage are induced in the sensor coils. These induced voltages can be used by the measurement system to calculate the position and the orientation of the magnetic field sensor in 3D space. In such cases, after the renal artery target position is detected by ultrasound imaging (in image coordinate), the transformation of the position may be performed as follows: 1) the treatment position and orientation of a target in the image coordinate are linked with the magnetic field sensor position and orientation based on mechanical design and calibration (in magnetic sensor coordinate); 2) the target position and orientation in the magnetic sensor coordinate are then transformed into the treatment module coordinate by the detection of the sensor position and orientation in the magnetic field generated by the magnetic field transmitter, and 3) the target position and orientation in the treatment module coordinate are further transformed into the coordinate of the therapeutic array. In some cases, the third transformation above is not needed if the coordinate frame of the therapeutic array is aligned with the treatment module coordinate frame. Therefore, knowing the position and orientation of the imaged target relative to the coordinate frame of the therapeutic array through the above transformations, the therapeutic system can adjust the mechanical movement of the therapeutic array and/or the phases of the array elements to deliver the ultrasound energy at the imaged treatment target. 
     In other embodiments, non-magnetic position measurement system may be used. This has the advantage of eliminating the possibilities of wrong targeting when a metal object gets close to the magnetic sensor and the transmitter. For example, in other embodiments, optical position measurement system may be used that measures the 3D positions of either active or passive markers affixed to application-specific tools. In one implementation, three different optical tool plates with at least three optical markers on each plate may be provided. One plate with optical markers is attached with the handle of the imaging transducer. The other two plates are attached on the left and right sides of the therapeutic treatment module separately. An optical position sensor system may be attached to the base of therapeutic treatment module. The optical position sensor system emits infrared (IR) light from its illuminators, similar to the flash on a conventional camera. The emitted IR light reflects back to the Position Sensor off markers (which may be spherical or semi-spherical) on the passive tool plates. The optical position sensor system then measures the positions of the markers and calculates the positions and orientations of the tool plates. The relationship of both positions and orientations between the tool plate attached to the imaging transducer (e.g., the handle) and the treatment module can be determined by the position sensor system at a rate of 20 Hz in real-time. To further optimize the detection accuracy of the positions and orientations between the imaging transducer and treatment module, the two plates which are attached along the left and right side of the treatment module are orientated to the optimized angles for treating the right and left renal denervation separately. In such cases, after the renal artery target position is detected by ultrasound imaging (in image coordinate), the transformation of the positions and orientations of the treatment target from the imaging coordinate to the therapy coordinate may be performed as follows: 1) the target position and orientation in the image coordinate are linked with the optical plate position (of the imaging transducer) based on mechanical design and calibration (to obtain treatment position and orientation in imaging tool plate coordinate); 2) the target position and orientation in the imaging tool plate coordinate are further transformed into optical position sensor coordinate frame; 3) the target position and orientation in the position sensor coordinate frame are then transformed into either left or right tool plate coordinate frame attached on the treatment module depending on the treatment of right or left side renal nerves; 4) the target position and orientation in the left/right treatment tool plate coordinate frame are further transformed to the therapeutic array coordinate frame based on mechanical design dimension and calibrations. Thus, the therapeutic system may control the therapeutic array to deliver the ultrasound energy to the treatment target through the above transformations by adjusting the mechanical movement of the therapeutic array and/or electronic phasing steering (e.g., in depth direction, and/or other direction(s)). 
     The systems and methods of the preferred embodiment and variations thereof can be embodied and/or implemented at least in part as a machine configured to receive a computer-readable medium storing computer-readable instructions. The instructions are preferably executed by computer-executable components preferably integrated with the imaging module and/or the therapy module. The computer-readable medium can be stored on any suitable computer-readable media such as RAMs, ROMs, flash memory, EEPROMs, optical devices (e.g., CD or DVD), hard drives, floppy drives, or any suitable device. The computer-executable component is preferably a general or application-specific processor, for example Versatile Data Acquisition System (VDAS), but any suitable dedicated hardware or hardware/firmware combination can alternatively or additionally execute the instructions. 
     In other embodiments, instead of or in addition to using histogram(s), a feature matching technique such as Normalized Cross Correlation method, Sum Square Difference method, Sum Absolute Difference method, etc., may be used. 
     The examples and illustrations included herein show, by way of illustration and not of limitation, specific embodiments in which the subject matter may be practiced. Other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Such embodiments of the inventive subject matter may be referred to herein individually or collectively by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept, if more than one is in fact disclosed. Thus, although specific embodiments have been illustrated and described herein, any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description.