Systems and methods for enhancing efficacy of ultrasound therapy

Abstract

Embodiments are provided for enhancing ultrasound efficacy with, for example, an efficient signal measurement, calibration, and assurance system using a control system radio frequency (RF) driver configured to drive one or more focused ultrasound transducers. In some embodiments, the RF driver may include one or more power amplifiers that include one or more III-V semiconductor (e.g., gallium nitride GaN, GaAs, GaSb, InP, InAs, InSb, InGaAs, AlSb, AlGaAs, and / or AlGaN) field effect transistors to provide high power efficiently over a wide frequency range through dissimilar narrow band RF signals. The RF driver may include a power metrology and / or calibration system to monitor the amplitude and phase of the RF signal output from the power amplifier and to estimate the amount of RF power delivered to the ultrasound transducers.

Description

[0001] This application is a divisional application of the invention patent application with application number 201980086756.3, application date November 25, 2019, and invention name “System and method for enhancing the effectiveness of ultrasound therapy”. Incorporation by reference

[0002] U.S. Provisional Patent Application No. 62 / 773,948, filed on November 30, 2019, is incorporated herein by reference in its entirety for all purposes. Technical Field

[0003] Several embodiments described herein are related to the assembly and electrical interconnection of high power, efficient radio frequency (RF) designs for complex voltage, current and power measurement, calibration and assurance of ultrasonic transducers. Various embodiments described in this application are related to electrical devices and systems configured to generate, monitor and deliver RF signals that power non-invasive treatments based on ultrasonic energy. Several embodiments are related to energy-based non-invasive treatments, such as for enhancing the efficacy of dermatological (e.g., cosmetic) ultrasonic treatments. Background Art

[0004] In the past, ultrasound has been used for diagnostic applications and therapeutic applications. Ultrasound imaging and therapy have been described for various medical applications, including dermatology. The use of ultrasound for cosmetic treatments has also been described. Summary of the invention

[0005] Several embodiments described herein provide systems and methods that overcome certain disadvantages in using ultrasound for therapeutic purposes, including, for example, excessive variation, error generation, and reduced therapeutic efficiency and effectiveness. In some embodiments, several enhancements are described that reduce signal harmonics that can interfere with signaling controls fed into an ultrasound transducer. Such reductions (e.g., via monitoring and calibration techniques) can ultimately reduce undesirable variability when using different ultrasound frequencies, powers, and / or depths, thereby enhancing the overall efficacy and effectiveness of ultrasound therapy.

[0006] In some embodiments, an efficient control system for directing power, voltage, current, and RF signals to one or more transducers included in the ultrasound therapy system described in the present application is provided. The RF module may include electronic devices, subsystems, and / or assemblies integrated on one or more printed circuit board assemblies.

[0007] In some embodiments, an ultrasound therapy board includes a power assurance system for high intensity focused ultrasound (HIFU) monitoring, which includes a power assurance measurement and calibration system for accurate, phase-sensitive measurement of electrical drive power to a HIFU transducer. In some embodiments, an ultrasound therapy panel includes: a HIFU switch mode power amplifier, which is combined with one or more high-efficiency transistors, such as Group III-V semiconductors (e.g., Group III-V compound semiconductors combining Group III elements (e.g., Ga, In, Al) and Group V elements (e.g., N, As, Sb, P), such as gallium nitride (GaN), gallium arsenide (GaAs), gallium antimonide (GaSb), indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), indium gallium arsenide (InGaAs), aluminum antimonide (AlSb), aluminum gallium arsenide (AlGaAs), aluminum gallium nitride (AlGaN), etc. Field effect transistors), wherein a radio frequency (RF) therapy power amplifier uses any of the Group III-V (e.g., gallium nitride (GaN)) field effect transistors and a power transformer (e.g., a Guanella transformer or other types of transformers) to deliver high-power RF energy to a high-intensity focused ultrasound transducer. In several embodiments, GaN transistors are described, but in other contemplated embodiments, any, two, three, or more of GaN, GaAs, GaSb, InP, InAs, InSb, InGaAs, AlSb, AlGaAs, and / or AlGaN transistors may be used. In various embodiments, one or more III-V semiconductors are not used, for example, are not included. In some embodiments, any one or more of GaN, GaAs, GaSb, InP, InAs, InSb, InGaAs AlSb, AlGaAs, and / or AlGaN are not used. In several embodiments, an ultrasound therapy board includes a system and method for predicting output power into an arbitrary HIFU transducer load, wherein the system uses calibration information stored by the power amplifier and transducer to predict the output power to be delivered by the amplifier into the transducer prior to delivering therapy. In some embodiments, an ultrasound therapy system includes: resistive current sensing and voltage sensing components; a demodulator capable of operating at any frequency; a phase-shift harmonic cancellation scheme; and / or a self-calibrating two-port compensation scheme.

[0008] In several embodiments, systems and methods are provided that successfully improve the efficiency of safety, effectiveness, and / or aesthetic results using directed and precise ultrasound to achieve visible and effective dermatological (e.g., cosmetic) results using ultrasound therapy that produces one or more focal zones for performing various treatments and / or imaging procedures via a thermal path. Various embodiments of the ultrasound therapy board may include a variety of health monitoring systems configured to ensure patient safety during operation. Additionally, systems and methods that can suppress and / or reduce harmonics in electrical signals output from the ultrasound therapy board to ensure patient safety are also encompassed in the present application.

[0009] In various embodiments, the present invention provides one or more advantages, such as reducing treatment time and / or errors; producing a unique heating pattern; utilizing multiple channels to obtain greater power; the option of treating areas at two or more depths with the same or different power levels (e.g., thermocoagulation, ablation, a real-time necrosis focal zone and another defocused energy, or other combinations); optional simultaneous or sequential treatment at different depths (e.g., at a depth of 1.5 mm, 3 mm and / or 4.5 mm thermocoagulation points below the skin surface simultaneously or in overlapping or sequential time periods); and / or treating with one, two or more simultaneous point, linear or line foci, such as at different depths below an area or spaced apart. Several embodiments described herein, whether for dermatological or non-dermatological applications, are particularly advantageous because they include one, some, or all of the following benefits: narrow bandwidth frequency ultrasound treatment at multiple depths with more efficient treatment, including one or more of the following: (i) faster treatment time; (ii) less pain during treatment; (iii) less pain after treatment; (iv) shorter recovery time; (v) more efficient treatment; (vi) higher customer satisfaction; (vii) less energy to complete treatment; and / or (viii) larger area treated by focal zone. In some embodiments, the advantages include modulating the effective amplitude of the driving transducer with a signal that drives the field effect transistor, the signal being generated by comparing the sinusoidal output of a direct digital synthesis circuit with a DC voltage.

[0010] In some embodiments, the electronics, subsystems and / or assemblies of the RF module may be configured to efficiently generate and deliver approximately 0.1 W to 200 W (e.g., approximately 20 to 100 W) of RF power to one or more ultrasonic transducers within a frequency range from 1 MHz to 20 MHz (e.g., approximately 1 MHz, 1.75 MHz, 1.75 to 12 MHz, 4 to 12 MHz, 4 MHz, 7 MHz, 10 MHz, 12 MHz). In particular, the RF module may include a power amplifier including a III-V (e.g., gallium nitride (GaN), GaAs, GaSb, InP, InAs, InSb, InGaAs, AlSb, AlGaAs, and / or AlGaN) field-effect transistor (FET) to efficiently (e.g., greater than or equal to 75%, 50% to 90%, 95%, 99%, or any value therein) generate one or more narrow-band RF signals at a frequency of 1.0 MHz to 12.0 MHz. Additionally, the RF module may include a power measurement system configured to monitor the amplitude and phase of the one or more RF signals generated by the III-V (e.g., GaN or other) FET. Furthermore, when paired with a drive system, a system and method for estimating the amount of power to be delivered by one or more ultrasonic transducers includes a power amplifier including a III-V (e.g., GaN or other) FET. In several embodiments, GaN transistors are described, but in other contemplated embodiments, any of GaN, GaAs, GaSb, InP, InAs, InSb, InGaAs, AlSb, AlGaAs, and / or AlGaN transistors may be used.

[0011] In various embodiments, an ultrasound therapy system comprises: an ultrasound probe comprising an ultrasound therapy transducer adapted to apply ultrasound therapy to tissue; and an electrical power system configured to provide electrical power to the ultrasound therapy transducer, the electrical power system comprising a power amplifier device and circuitry; wherein the power amplifier device comprises at least one semiconductor transistor, wherein the semiconductor transistor is a field effect transistor, wherein the field effect transistor is configured to operate at a radio frequency (RF) in a range between 200 kHz and 20 MHz with an efficiency of at least 75%. In one embodiment, the semiconductor transistor comprises a III-V compound. In one embodiment, the semiconductor transistor comprises gallium nitride (GaN).

[0012] In one embodiment, the power amplifier device comprises: a switch-mode amplifier design including at least a semiconductor; and a circuit configured to generate a digital waveform to drive the semiconductor, thereby driving an ultrasound therapy transducer. In one embodiment, the power amplifier device comprises: a switch-mode amplifier design including at least one semiconductor, wherein in one embodiment, each semiconductor includes a plurality of (or a plurality of) gates (in another embodiment, each gallium nitride field effect transistor does not include a plurality of gates); and a circuit configured to generate a digital waveform to drive the semiconductor, thereby driving an ultrasound therapy transducer. In one embodiment, the power amplifier device comprises: a switch mode amplifier design including at least one GaN field effect transistor, wherein in one embodiment, each GaN field effect transistor includes a plurality of gates (in another embodiment, each GaN field effect transistor does not include a plurality of gates); and a circuit configured to generate a digital waveform to drive a plurality of gates of a GaN field effect transducer, thereby driving an ultrasound therapy transducer, which in one embodiment is a piezoelectric ultrasound therapy transducer. In one embodiment, the signal driving the field effect transistor is generated by comparing the output of a sinusoidal direct digital synthesis circuit with a DC voltage. In one embodiment, the system includes generating a signal driving the field effect transistor by comparing the sinusoidal output of the direct digital synthesis circuit with a DC voltage, the signal being configured to modulate the effective amplitude of the driving transducer. In one embodiment, the output power is in the range of 5W to 50W or 30W to 100W. In one embodiment, the circuit comprises four transistors configured in an H-bridge configuration. In one embodiment, the circuit includes four gallium nitride transistors configured in an H-bridge configuration. In one embodiment, the circuit includes two transistors configured in a half-bridge configuration. In one embodiment, the circuit includes two gallium nitride transistors configured in a half-bridge configuration. In one embodiment, the gate drive signal has a variable duty cycle for controlling the harmonic content and power in the output signal. In one embodiment, the power amplifier converter supplies power to the RF output signal power supply with an efficiency greater than 75%. In one embodiment, the supply voltage to the power amplifier is modulated (or modulated) using a switch-mode DC-DC converter, which reduces a fixed high voltage input to a lower supply voltage. In one embodiment, the system includes two or more power amplifiers, wherein a single power amplifier is configured to drive a single piezoelectric transducer element of a high-intensity focused ultrasound transducer. In one embodiment, the high-intensity focused ultrasound transducer is configured to be driven by a separate power amplifier. In one embodiment, the high-intensity focused ultrasound transducer includes a plurality of piezoelectric transducer elements, each of the plurality of piezoelectric transducer elements being configured to be driven by a separate power amplifier.In one embodiment, the power amplifier is configured to drive the output at two or more different amplitudes. In one embodiment, the power amplifier is configured to drive the output at two or more different phases. In one embodiment, the amplifier is configured to drive the output at two or more different frequencies. In one embodiment, the phase and frequency are controlled by a direct digital synthesizer. In one embodiment, the system is configured to drive a transducer having an impedance in the range of from 20 ohms to 120 ohms and a phase angle of from +45 degrees to -45 degrees.

[0013] In one embodiment, the power amplifier device includes: a switch mode amplifier design including at least one field effect transistor; and a circuit configured to generate a digital waveform to drive a plurality of gates of a field effect transducer, thereby driving a piezoelectric ultrasonic transducer; wherein the circuit includes four transistors configured in an H-bridge configuration.

[0014] In one embodiment, the power amplifier device comprises: a switch mode amplifier design including at least one field effect transistor; and a circuit configured to generate a digital waveform to drive a plurality of gates of the field effect transducer, thereby driving the piezoelectric ultrasonic transducer; wherein the signal to drive the field effect transistor is generated by comparing the output of a sinusoidal direct digital synthesis circuit with a DC voltage; wherein the output power is in the range of 30W to 100W; wherein the circuit comprises four transistors configured in an H-bridge configuration.

[0015] In one embodiment, the semiconductor is gallium nitride, wherein the power amplifier device comprises: a switch mode amplifier design including at least one gallium nitride field effect transistor, wherein each gallium nitride field effect transistor includes a plurality of gates; and a circuit configured to generate a digital waveform to drive a plurality of gates of a gallium nitride field effect transducer to drive a piezoelectric ultrasonic transducer; wherein the signal to drive the field effect transistor is generated by comparing the output of a sinusoidal direct digital synthesis circuit with a DC voltage; wherein the output power is in the range of 30W to 100W; wherein the circuit includes four gallium nitride transistors configured in an H-bridge configuration; wherein the gate drive signal has a variable duty cycle for controlling the harmonic content and power in the output signal; wherein the power amplifier converter is operated at a frequency greater than 75% efficiency to supply power to a radio frequency output signal power supply; wherein a supply voltage to a power amplifier is modulated using a switch mode DC-DC converter that reduces a fixed high voltage input to a lower supply voltage; comprising two or more power amplifiers, wherein a single power amplifier is configured to drive a single piezoelectric transducer element of a high intensity focused ultrasound transducer; wherein the power amplifier is configured to drive the output at two or more different amplitudes; wherein the power amplifier is configured to drive the output at two or more different phases; wherein the phase and frequency are controlled by a direct digital synthesizer; wherein the system is configured to drive a transducer having an impedance in the range of 20 ohms to 120 ohms and a phase angle from +45 degrees to -45 degrees.

[0016] In various embodiments, a power amplifier device for driving a high-intensity ultrasonic transducer comprises: a switch-mode amplifier design including at least one field effect transistor; and a circuit configured to generate a digital waveform to drive the at least one field effect transistor. In various embodiments, a power amplifier device for driving a high-intensity ultrasonic transducer comprises: a switch-mode amplifier design including at least one gallium nitride field effect transistor; and a circuit configured to generate a digital waveform to drive the at least one gallium nitride field effect transistor.

[0017] In various embodiments, a power amplifier device for driving a high-intensity ultrasonic transducer includes: a switch-mode amplifier design including at least one GaN field effect transistor, wherein each GaN field effect transistor includes a plurality of gates; and a circuit configured to generate a digital waveform to drive a plurality of gates of the GaN field effect transducer, thereby driving a piezoelectric ultrasonic transducer. In one embodiment, a power amplifier device for driving a high-intensity ultrasonic transducer includes: a switch-mode amplifier design including a plurality of GaN field effect transistors; and a circuit configured to generate a digital waveform to drive a plurality of GaN field effect transducers, thereby driving a piezoelectric ultrasonic transducer.

[0018] In various embodiments, a power amplifier device includes one or more of the following features: wherein the power amplifier is configured to drive the output at two or more different amplitudes, wherein the power amplifier is configured to drive the output at two or more different phases. In one embodiment, the power amplifier is configured to drive the output at two or more different frequencies.

[0019] In various embodiments, a method of controlling electrical power in an ultrasonic system for delivering a desired amount of focused acoustic power through an ultrasonic transducer comprises: providing an electrical power control system comprising a circuit and a control system look-up table (LUT), the circuit comprising a control system microprocessor; providing an ultrasonic transducer comprising a transducer controller, a transducer microprocessor, and a transducer LUT; determining, using the transducer microprocessor from the transducer LUT, an amount of electrical power delivered to a load that is equal to a desired amount of acoustic power delivered to tissue by the ultrasonic transducer; determining, using the control system microprocessor from the control system LUT, an amplitude of an electrical signal output from a power amplifier of the electrical power system that will deliver an equal amount of electrical power delivered to the load; and setting at least one parameter of the electrical power system that outputs the determined amplitude of the electrical signal output by the electrical power system. In various embodiments, the load is in the range of 10 ohms to 100 ohms or 20 ohms to 120 ohms (e.g., 10 to 40, 40 to 80, 80 to 120, and overlapping ranges therein), which permits a wider range of transducer impedances to occur during phasing / focusing of the transducer. In one embodiment, the load is 50 ohms.

[0020] In various embodiments, an ultrasound therapy system includes: an ultrasound probe including a housing containing a piezoelectric active ultrasound therapy transducer adapted to focus acoustic ultrasound in a focal zone in tissue at a depth from the housing; an electrical power system configured to provide electrical power to the ultrasound therapy transducer, the electrical power system including a power amplifier; and an electrical power measurement system configured to monitor electrical output power from an output signal from the power amplifier, wherein the electrical power measurement system includes: a resistive current sensing circuit configured to monitor current output from the power amplifier; and a resistive voltage sensing circuit configured to monitor voltage output from the power amplifier, and wherein the electrical power measurement system is configured to monitor the electrical output power from the power amplifier over a frequency range spanning at least two octaves for the ultrasound therapy transducer.

[0021] In various embodiments, a system for measuring radio frequency (RF) current and voltage of a driving circuit in a high-intensity focused ultrasound system includes: a current sensing resistor connected in series with a load; a shunt voltage sensing resistor network connected in parallel with the load; and an electric power output voltage and current monitoring circuit (IQ demodulator circuit) having a local oscillator clock synchronized in phase and frequency with a signal driving a power amplifier and configured to demodulate the output signal to a carrier frequency lower than the ultrasonic driving frequency.

[0022] In one embodiment, the measurement system is configured to make multiple measurements at different relative phase shifts between the local oscillator and the power amplifier. In one embodiment, the local oscillator clock is generated by a self-controlled direct digital synthesizer. In one embodiment, the measurement system is configured to make multiple measurements at the local oscillator frequency. In one embodiment, the number of phase measurements is 6. In one embodiment, the system uses the measurement system to modify the gate drive signal so as to achieve the desired harmonic content in the output signal.

[0023] In various embodiments, the method for determining the number of measurements adequately measures harmonics by evaluating the number of harmonics in the passband whose lowest frequency exceeds the system noise floor. In one embodiment, the composite harmonic components of the voltage and current waveforms are calculated by forming linear combinations of multiple measurements.

[0024] In various embodiments, a method for calibrating a high intensity ultrasonic transducer includes: calibrating an acoustic output power delivered by the transducer for a driver configuration, the acoustic output power corresponding to an electrical power delivered by the driver into one or more reference loads for the driver configuration, wherein calibration information is stored by the transducer; calibrating an electrical driver configuration against the electrical power delivered into one or more reference loads, wherein the calibration information is stored by the driver; and performing calculations using a processor of the driver configuration to achieve a desired acoustic output power, the processor using the transducer calibration information to determine a power level into one or more reference loads for a desired acoustic power setting, and using the driver calibration information to determine a driver configuration for a desired acoustic output power level into the reference loads.

[0025] In one embodiment, the transducer calibration information also includes the electrical power delivered by the transducer at each acoustic power level, wherein the stored power information includes a composite power component or an actual power component. In one embodiment, dynamic measurement of the electrical power delivered from the driver is made during tissue insonification and verified against the electrical power stored in the transducer calibration information for the desired acoustic power level.

[0026] In various embodiments, a method for tuning a high intensity focused ultrasound transducer by sweeping the frequency while measuring a voltage standing wave ratio at a driver and selecting the frequency that minimizes the voltage standing wave ratio as the operating frequency.

[0027] In one embodiment, the acoustic output power is generated by performing measurements using a force balance. In one embodiment, the transducer calibration information is stored as a lookup table in a non-volatile memory chip inside the transducer. In one embodiment, at least one of the voltage or current measured at the driver is adjusted using a transfer matrix describing a two-port network between the therapy drive circuit output and the transducer. In one embodiment, the calibration information is stored in a lookup table (LUT). In one embodiment, the target voltage is calculated from the calibration information and the desired acoustic power set in the clinic by interpolating values ​​in one or more lookup tables. In one embodiment, an electrical power threshold value (or threshold value, threshold) at each acoustic power level is stored in the transducer calibration information to define an acceptable range of electrical drive power to achieve an acceptable range of acoustic output power.

[0028] In various embodiments, a system for confirming that dynamically measured electrical power is within a specified range includes dynamically measuring electrical power delivered by a driver and comparing the electrical power to a threshold value stored in a transducer. In one embodiment, a transfer matrix of a handpiece and cable assembly that is interchangeable between the transducer and the driver is stored on a non-volatile memory chip within the handpiece and cable assembly.

[0029] In various embodiments, a method for dynamically adjusting power by measuring electrical power delivered from a drive; comparing the measured electrical power to a desired electrical power determined from calibration information; and adjusting the drive configuration to reduce an error between the desired electrical power and the measured electrical power.

[0030] In various embodiments, a method for dynamically adjusting power by measuring the electrical impedance of a load and calculating the transducer impedance based on the known impedances of other system components; calculating the electrical power required by the driver to maintain the same amount of dissipated power across the actual transducer impedance; and adjusting the driver configuration to meet the electrical power required to reduce the error between the desired electrical power and the measured electrical power. In one embodiment, the power is dynamically adjusted whenever therapy is delivered.

[0031] In one embodiment, the transducer calibration information also includes electrical power delivered to the transducer at each acoustic power level, wherein the stored power information includes a composite power component or an actual power component; wherein dynamic measurement of the electrical power delivered from the driver is performed during tissue insonification and verified against the electrical power stored in the transducer calibration information for the desired acoustic power level.

[0032] In one embodiment, the transducer calibration information also includes the electrical power delivered to the transducer at each acoustic power level, wherein the stored power information includes a composite power component or an actual power component; wherein dynamic measurement of the electrical power delivered from the driver is performed during tissue insonification and verified against the electrical power stored in the transducer calibration information for the desired acoustic power level; wherein the acoustic output power is generated by performing the measurement using a force balance; wherein the transducer calibration is stored as a lookup table in a non-volatile memory chip inside the transducer; wherein at least one of the voltage or current measured at the driver is adjusted using a transfer matrix describing a two-port network between the therapeutic drive circuit output and the transducer; wherein the calibration information is stored in a lookup table (LUT); wherein the target voltage is calculated from the calibration information and the desired acoustic power set in the clinic by interpolating values ​​in one or more lookup tables.

[0033] In various embodiments, a method for detecting the quality of acoustic coupling of a high intensity focused ultrasound transducer through a skin surface by measuring the amount of reflected energy includes: measuring the amount of reflected energy using a therapy transducer sensor; determining a distance between a piezoelectric therapy transducer bowl and a coupling surface; measuring a first power measurement before reflection from the coupling surface; measuring a second power measurement after reflection from the coupling surface; and calculating a difference calculation to determine the amount of reflected power.

[0034] In one embodiment, the amount of reflected energy is measured by an auxiliary transducer not used for therapy. In one embodiment, after the power change (forward minus reverse) is calculated, therapy is temporarily stopped until sufficient time has passed to eliminate reflections from the self-coupling surface as detected by the auxiliary transducer or the therapy transducer. In one embodiment, once the reflected energy drops below a threshold, the therapy driver re-engages and energizes the therapy transducer. In one embodiment, the high intensity ultrasound transducer comprises a multi-element array transducer and calibration information is stored for each element in the array.

[0035] In one embodiment, the drivers are housed in a system control panel and the transducers are interchangeable between system control panels. In one embodiment, the transducers are interchangeable between handpieces and the handpieces are interchangeable between consoles.

[0036] In various embodiments, a method for calibrating a high intensity focused ultrasound transducer includes: modeling a driver as a Thevenin equivalent source having a frequency dependent source voltage and source impedance, and storing calibration information including the source voltage and source impedance with the driver; measuring the transducer impedance and storing it in the calibration information on the transducer; and calculating the electrical power delivered by the driver to the transducer as a load impedance stored in the transducer calibration information using the source voltage and source impedance stored in the driver calibration information, and treating the combined system as a voltage divider network.

[0037] In various embodiments, a method for measuring transducer impedance: calibrating a driver using one or more known reference impedances; measuring transducer impedance at one or more frequencies and one or more amplitudes; mounting the measured transducer in a resonant circuit to calculate transducer parameters such as clamping capacitance, coupling coefficient, and radiation resistance; using characteristics to determine transducer lifetime, operational acceptability, and required amplitude and phase.

[0038] In one embodiment, the distance between the transducer and the intended treatment zone is fixed. In one embodiment, the treatment beam is temporarily moved to an untreated zone to determine the amount of backscatter from the treatment zone using a differential method.

[0039] In various embodiments, an ultrasound therapy system includes: an ultrasound probe comprising an ultrasound therapy transducer adapted to apply ultrasound therapy to tissue; and an electrical power system configured to provide electrical power to the ultrasound therapy transducer, the electrical power system comprising a power amplifier device and a circuit; wherein the power amplifier device comprises at least one III-V semiconductor power transistor, the semiconductor power transistor being configured to operate at a radio frequency (RF) in a range between 200 kHz and 20 MHz with an efficiency of at least 75%.

[0040] In one embodiment, at least one III-V semiconductor power transistor is selected from the group consisting of: GaN, GaAs, GaSb, InP, InAs, InSb, InGaAs, AlSb, AlGaAs, and AlGaN. In one embodiment, at least one III-V semiconductor power transistor is gallium nitride. In one embodiment, at least one III-V semiconductor power transistor is not one of GaN, GaAs, GaSb, InP, InAs, InSb, InGaAs, AlSb, AlGaAs, and AlGaN. In one embodiment, the power amplifier device includes: a switch mode amplifier design including a plurality of III-V semiconductor power transistors; and a circuit configured to generate a digital waveform to drive the plurality of III-V semiconductor power transistors to drive the piezoelectric ultrasonic transducer. In one embodiment, the signal driving the power transistor is generated by comparing the output of a sinusoidal direct digital synthesis circuit with a DC voltage. In one embodiment, the output power is in the range of 30W to 100W. In one embodiment, the output power is in the range of 5W to 50W. In one embodiment, the circuit comprises four power transistors configured in an H-bridge configuration. In one embodiment, the gate drive signal has a variable duty cycle for controlling the harmonic content and power in the output signal. In one embodiment, the power amplifier converter supplies power to the RF output signal power supply with an efficiency greater than 75%. In one embodiment, the supply voltage to the power amplifier is modulated using a switch mode DC-DC converter, which reduces the fixed high voltage input to a lower supply voltage. In one embodiment, the system comprises two or more power amplifiers, wherein a single power amplifier is configured to drive a single piezoelectric transducer element of a high intensity focused ultrasound transducer. In one embodiment, the power amplifier is configured to drive the output at two or more different amplitudes. In one embodiment, the power amplifier is configured to drive the output at two or more different phases. In one embodiment, the phase and frequency are controlled by a direct digital synthesizer. In one embodiment, the system is configured to drive a transducer having an impedance in the range of 20 ohms to 120 ohms and a phase angle from +45 degrees to -45 degrees.

[0041] In various embodiments, a power amplifier device for driving a high intensity ultrasonic transducer includes: a switch mode amplifier design including at least one III-V semiconductor power transistor; and a circuit configured to generate a digital waveform to drive the at least one III-V semiconductor power transistor.

[0042] In various embodiments, an apparatus having a plurality of power amplifiers for driving a high-intensity ultrasonic transducer includes: a switch-mode amplifier design including a plurality of III-V semiconductor power transistors; and a circuit configured to generate a digital waveform to drive the plurality of III-V semiconductor power transistors to drive a piezoelectric ultrasonic transducer.

[0043] In one embodiment, the III-V semiconductor power transistor is a gallium nitride field effect transistor. In one embodiment, the power amplifier is configured to drive the output at two or more different amplitudes, and / or the power amplifier is configured to drive the output at two or more different phases.

[0044] In various embodiments, a method of controlling electrical power in an ultrasonic system for delivering a desired amount of focused acoustic power through an ultrasonic transducer comprises: providing an electrical power control system comprising a circuit and a control system lookup table (LUT), the circuit comprising a control system microprocessor; providing an ultrasonic transducer comprising a transducer controller, a transducer microprocessor, and a transducer LUT; determining (or determining) from the transducer LUT, using the transducer microprocessor, an amount of electrical power delivered to a load that is equal to a desired amount of acoustic power delivered to tissue by the ultrasonic transducer; determining from the control system LUT, using the control system microprocessor, an amplitude of an electrical signal output from a power amplifier of the electrical power system that will deliver an equal amount of electrical power delivered to the load; and setting at least one parameter of the electrical power system that outputs the determined amplitude of the output electrical signal, wherein the load is in the range of 20 ohms to 120 ohms. In one embodiment, the load is 50 ohms.

[0045] In various embodiments, an ultrasonic therapy system includes: an ultrasonic probe, which includes a housing, the housing including a piezoelectric active ultrasonic therapy transducer, the piezoelectric active ultrasonic therapy transducer is adapted to focus acoustic ultrasound in a focal zone in tissue at a certain depth from the housing; an electrical power system, which is configured to provide electrical power to the ultrasonic therapy transducer, the electrical power system includes a power amplifier; and an electrical power measurement system, which is configured to monitor electrical output power from an output signal from the power amplifier, wherein the electrical power measurement system includes: a resistive current sensing circuit, which is configured to monitor the current output from the power amplifier; and a resistive voltage sensing circuit, which is configured to monitor the voltage output from the power amplifier, and wherein the electrical power measurement system is configured to monitor the electrical output power from the power amplifier within a frequency range spanning at least two octaves for the ultrasonic therapy transducer.

[0046] In various embodiments, a system for measuring radio frequency (RF) current and voltage of a driving circuit in a high intensity focused ultrasound system includes: a current sensing resistor connected in series with a load; a shunt voltage sensing resistor network connected in parallel with the load; and an electrical power output voltage and current monitoring circuit (IQ demodulator circuit) having a local oscillator clock synchronized in phase and frequency with a signal driving a power amplifier and configured to demodulate (or demodulate) the output signal to a carrier frequency lower than the ultrasonic driving frequency.

[0047] In one embodiment, the measurement system is configured to make multiple measurements at different relative phase shifts between the local oscillator and the power amplifier. In one embodiment, the local oscillator clock is generated from an independently controlled direct digital synthesizer. In one embodiment, the number of phase measurements is 6. In one embodiment, the measurement system is configured to modify the gate drive signal so as to achieve the desired harmonic content in the output signal. In one embodiment, the method for determining the number of measurements is configured to adequately measure harmonics by evaluating the number of harmonics in the passband whose lowest frequency exceeds the system noise floor.

[0048] In various embodiments, an ultrasound treatment system has one or more of the features described in this specification. In various embodiments, a power amplifier device for driving a high-intensity ultrasound transducer has one or more of the features described in this specification. In various embodiments, a method for controlling electrical power in an ultrasound system has one or more of the features described in this specification. In various embodiments, a system for measuring radio frequency (RF) current and voltage of a drive circuit in a high-intensity focused ultrasound system has one or more of the features described in this specification. In various embodiments, a method for calibrating a high-intensity ultrasound transducer has one or more of the features described in this specification. In various embodiments, a method for detecting the quality of acoustic coupling of a high-intensity focused ultrasound transducer through the skin surface has one or more of the features described in this specification.

[0049] In addition, the applicable fields will become apparent from the description provided herein. It should be understood that the description and specific examples are intended only for illustrative purposes and are not intended to limit the scope of the embodiments disclosed herein. In some embodiments, the system includes various features that exist as a single feature (compared to multiple features). For example, multiple features or components are provided in alternative embodiments. In various embodiments, the system includes, is essentially composed of, or is composed of: one, two, three or more three embodiments of any feature or component disclosed herein. In some embodiments, a feature or component is not included and can be negated from a specific technical solution so that the system does not have this feature or component. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. Embodiments of the present invention will be more fully understood from the implementation methods and the accompanying drawings, in which:

[0051] Figure 1A is a schematic illustration of an ultrasound system according to various embodiments of the present invention.

[0052] Figure 1B is a schematic illustration of an ultrasound system according to various embodiments of the present invention.

[0053] Figure 1C is a schematic illustration of an ultrasound system according to various embodiments of the present invention.

[0054] Figure 2 is a schematic illustration of an ultrasound system coupled to a region of interest according to various embodiments of the present invention.

[0055] Figure 3A-3B A block diagram illustrating an embodiment of a radio frequency (RF) therapy (TH) module including a drive subsystem configured to generate an RF signal at a desired RF power and within a desired frequency range to drive an ultrasound transducer.

[0056] Figure 4 An embodiment of a transmission line transformer is depicted that is configured to convert a balanced H-bridge output to a ground referenced source and act as an impedance matching stage for a low impedance GaN FET to an impedance presented by one or more ultrasonic transducers. In one embodiment, the transmission line transformer is configured to increase the source impedance seen by the ultrasonic transducer when driven by the GaN FET to the impedance presented by the one or more ultrasonic transducers.

[0057] Figure 5A An example implementation of an H-bridge design topology is described. Figure 5B (connect the load in one direction) and Figure 5C (Connecting the load in the other direction) illustrates the operation of the H-bridge in two different configurations.

[0058] Figure 6 The drive signals generated by the H-bridge are shown when the duty cycle of the positive portion of the waveform and the negative portion of the waveform is set to 0.3 according to various embodiments of the present invention.

[0059] Figure 7 The variation of the amplitude of the high odd harmonics for different duty cycles of the positive portion of the waveform and the negative portion of the waveform according to various embodiments of the invention is shown.

[0060] FIG. 8A to FIG. 8D Output signals from an implementation of a power amplifier using an H-bridge design at 2.0 MHz, 4.0 MHz, 7.0 MHz, and 12.0 MHz, respectively, are shown according to various embodiments of the invention.

[0061] Fig. 9 A simplified schematic diagram of a comparator circuit to generate two drive waveforms that are 180 degrees out of phase with each other is shown in accordance with various embodiments of the invention.

[0062] Fig.10 Graphically illustrate the Fig. 9 The circuit generates two driving waveforms.

[0063] Fig.11A Simplified circuit diagrams illustrating a switch mode power amplifier including an H-bridge formed of four (4) GaN FETs driving the balanced side of a 1:9 Guanella transmission line transformer according to various embodiments of the present invention.

[0064] Fig. 11B Implementations of protection circuits included in various implementations of switch-mode power amplifiers according to various embodiments of the invention are depicted.

[0065] Figure 11C-Figure 11D Implementation of a voltage-controlled buck converter according to various embodiments of the present invention is described.

[0066] Fig.12 A differential measurement scheme including a broadband small-signal RF transformer according to various embodiments of the present invention is described.

[0067] Fig.13 Implementations of power measurement circuits configured to measure an RF signal output from implementations of a power amplifier are shown according to various embodiments of the invention.

[0068] Fig.14 A block diagram of an IQ demodulator according to various embodiments of the present invention is shown.

[0069] Fig.15 Two internal clocks generated by an embodiment of an IQ demodulator are shown.

[0070] Fig.16 Circuit operation of multiplying an RF signal by a square wave having a maximum value of 1 and a minimum value of -1 according to various embodiments of the present invention is illustrated.

[0071] Fig.17 I and Q demodulation of a sinusoidal signal according to various embodiments of the invention is shown.

[0072] Fig.18A An oscilloscope trace is shown from an implementation of a power amplifier into a 50 ohm load operating at an operating frequency of approximately 12.0 MHz. Fig.18B Oscilloscope traces are shown from implementations of a power amplifier according to various embodiments of the invention to output into a 50 ohm load operating at an operating frequency of approximately 1.75 MHz. In various embodiments, on-board calibration allows the system to modify the drive circuit based on operating conditions (temperature) or aging of the device without factory calibration.

[0073] Fig.19A and Fig.19B The magnitude of the fast Fourier transform (FFT) of an RF signal at the low frequency end of the passband (normalized to fundamental frequency 1) and the magnitude of the fast Fourier transform (FFT) of a square wave are shown according to various embodiments of the invention.

[0074] Fig. 20 A harmonic cancellation scheme using a phase-shifted clock according to various embodiments of the present invention is described.

[0075] Fig.21 Output signals from implementations of demodulators according to various embodiments of the invention are shown.

[0076] FIG. 22A to FIG. 22C An example of reconstructing an RF signal output from a power amplifier at three different frequencies according to various embodiments of the invention is shown.

[0077] Fig.23A Various mechanisms that affect RF signal propagation from an implementation of a power amplifier delivered to an ultrasonic transducer (eg, RF signal losses, phase changes, etc. that may reduce the power of the RF signal output) are schematically illustrated. Fig. 23B An equivalent two-port network is shown according to various embodiments of the invention that takes into account various mechanisms of RF signal propagation (eg, losses, phase changes, etc.).

[0078] Fig.24Implementations of power measurement systems including equivalent two-port networks according to various embodiments of the invention are shown that take into account various mechanisms of RF signal propagation (e.g., losses, phase changes, etc.). In one embodiment, the 2-port network is not necessarily "lossy", some components may, for example, only introduce phase changes. DETAILED DESCRIPTION

[0079] The following description sets forth examples of embodiments and is not intended to limit the present invention or its teachings, applications, or uses. It should be understood that throughout the accompanying drawings, corresponding reference numerals indicate identical or corresponding parts and features. The description of specific examples indicated in various embodiments of the present invention is intended to be used for illustrative purposes only and is not intended to limit the scope of the present invention disclosed herein. In addition, the description of multiple embodiments with stated features is not intended to exclude other embodiments with additional features or other embodiments incorporating different combinations of stated features. In addition, features in one embodiment (such as, in one figure) may be combined with descriptions (and figures) of other embodiments.

[0080] Several embodiments of novel and inventive systems and methods are described herein that provide efficient control of directing power, voltage, current, and radio frequency (RF) signals to one or more focused energy-based systems. In various embodiments, the control system includes electronic devices, subsystems, and / or assemblies integrated on one or more printed circuit board assemblies. System architecture, circuit systems, modeling, design, implementation, and verification are related to improvements in providing efficient power, voltage, and current to direct ultrasound therapy systems. In various embodiments, an energy-based system includes interchangeable components (e.g., control panels, handpieces, transducer detection modules, etc.) that are calibrated to operate efficiently and effectively and communicate with each other to provide the desired treatment effect. The efficient and effective focusing performance of ultrasound at a specific distance from the ultrasound transducer is improved by reducing deviations, errors, and harmonics that can interfere with optimal performance. In some embodiments, dermatological applications (including, for example, cosmetic and non-cosmetic dermatological applications) are provided. In other embodiments, non-dermatological applications (such as orthopedics, neurology, cardiology, etc.) are provided. Overview of Ultrasound Therapy System

[0081] refer to Figure 1A , Figure 1B and Figure 1CAs described in , various embodiments of the ultrasound therapy system 20 include a handle (e.g., handpiece) 100, a module (e.g., transducer module, cassette, probe) 200, and a controller (e.g., console) 300. In some embodiments, a cart 301 provides mobility and / or location of the system 20, and may include wheels, a surface for writing or placing components on it, and / or compartments 302 (e.g., drawers, containers, shelves, etc.) for storing or organizing components, for example. In various embodiments, the controller 300 may be adapted and / or configured for operation with the handle 100 and the module 200 and the entire ultrasound system 20 functionality. In various embodiments, multiple controllers 300, 300', 300", etc. can be adapted and / or configured for operation with multiple handles 100, 100', 100", etc. and / or multiple modules 200, 200', 200", etc. In various embodiments, the controller 300 may include a system processor and various analog and / or digital control logic, such as one or more of the following: a microcontroller, a microprocessor, a field programmable gate array, a computer board and associated components, including firmware and control software, which can interface with user controls and interface circuits and input / output circuits and systems for communication, display, interfacing, storage, documentation and other useful functions. The system software running on the system processor can be adapted and / or configured to control all initialization, timing, level setting, monitoring, safety monitoring and all other ultrasound system functions to achieve user-defined treatment goals. In addition, the controller 300 may include various input / output modules, such as switches, buttons, etc., which can also be appropriately adapted and / or configured to control the operation of the ultrasound system 20. Figure 2 Schematic illustration of ultrasound system 20 coupled to region of interest 10 of individual 500 having skin surface 501, epidermis 502, dermis 503, fat layer 505, superficial musculoaponeurotic system 507 (hereinafter "SMAS 507"), and muscle layer 509. Ultrasonic Controller Overview

[0082] As discussed herein, in various embodiments, the controller 300 may be adapted and / or configured to include, for example, a microprocessor with software and input / output devices, systems and devices for controlling electronic and / or mechanical scanning and / or multitasking of transducers and / or multitasking of transducer modules, systems for power delivery, systems for monitoring, systems for sensing spatial position of probes and / or transducers and / or multitasking of transducer modules, and / or systems for handling user input and recording treatment effects, among other systems. In various embodiments, the controller 300 may be configured to provide radio frequency (RF) power to drive one or more ultrasonic transducers. In various embodiments, the controller 300 may include an RF therapy (RFTH) module that includes electronic devices and / or electronic subsystems configured to generate RF power within a desired range of RF power and within a desired frequency range that can drive one or more ultrasonic transducers. The RFTH module may include a printed circuit board (PCB) assembly including subsystems for delivering and monitoring RF signals that drive one or more ultrasonic transducers. The PCB assembly may include one or more RF signal generators, one or more RF power amplifiers, one or more oscillators, one or more temperature monitors, one or more power monitors, one or more power supplies, one or more timing circuits and / or other electronic components configured to generate RF signals within a desired range of power and within a desired range of frequency, a system that can measure the power of the RF signal and / or a calibration system that can predict the RF power that will be delivered to the one or more ultrasonic transducers.

[0083] Figure 3A and Figure 3B A block diagram illustrating an implementation of an RFTH module including a driver subsystem 3000 configured to generate RF signals at a desired RF power and within a desired frequency range to drive ultrasonic transducers. In one embodiment, the RFTH module may include eight (8) driver subsystems configured to generate eight (8) RF signals at a desired RF power and within a desired frequency range to drive eight (8) ultrasonic transducers. In other embodiments, the number of driver subsystems of the RFTH module may be less than eight (e.g., 7, 6, 5, 4, 3, 2, 1) or greater than eight (e.g., 9, 10, 11, 12, 13, 15, 20, or more than 20).

[0084] The drive subsystem 3000 includes a power amplifier (PA) 3001 that generates an RF output signal at a desired frequency and phase and with a desired RF power amount. The drive subsystem 3000 may further include a power supply system 3011 configured to supply power to the power amplifier 3001. The generated RF signal may be directed to an on-board 50Ω load 3003 for diagnosis and calibration, or to an output connector 3005 of an ultrasonic transducer connected to the handle 100 and / or module 200. The drive subsystem 3000 further includes a power measurement system 3007 that monitors the electrical output power from the power amplifier to the ultrasonic transducer. The power measurement system 3007 may be configured to sample the composite voltage on the output connector 3005 and the current flowing into the output connector. In various embodiments, the IQ demodulator is an electrical power output voltage and current monitoring circuit. The power measurement system 3007 includes an IQ demodulator that demodulates the RF signal to a baseband using a synchronous clock. This may facilitate real-time high-resolution monitoring of the phase of the RF power output from output connector 3005 and / or facilitate estimation of the thermal dose delivered to the patient.

[0085] Some embodiments of the RFTH module including a plurality of driving subsystems 3000 may be configured to provide a phase-locked driving signal having a controllable frequency and phase to the plurality of driving subsystems 3000. For example, a clock distribution circuit 3010 including three 4-channel dynamic digital synthesizer (DDS) integrated circuits (ICs) may be used to provide a phase-locked driving signal having a controllable frequency and phase. Two of the three DDSs may provide the driving signal to the power amplifiers 3001 of the plurality of driving subsystems 3000, while the third DDS provides a reference clock signal to a demodulator IC in a power measurement system 3007 for synchronous demodulation.

[0086] Because proper operation of the RFTH module is critical to patient safety, the RFTH module may include a variety of health monitoring systems configured to ensure proper operation of the RFTH module. For example, the RFTH module may include one or more temperature monitors 3009 that monitor the temperature at various parts of the RFTH module. In one embodiment of the RFTH module, the one or more temperature monitors may be configured to monitor the temperature at thirty-two (32) different locations around the RFTH module. In various embodiments, the one or more temperature monitors 3009 may be configured to receive temperature measurements from one or more sensors disposed at various locations of the RFTH module. The RFTH module may include one or more power supply monitors 3013 to monitor the voltage and / or current provided by the power supply system 3011 to the power amplifier 3001. In some embodiments, the RFTH module may include a control current limit (ICTRL) device 3015 that controls the maximum supply current supplied to the power amplifier 3001. The RFTH module may include a relay monitor 3017 that is configured to ensure that various relays (e.g., relay 3018) switch when commanded to switch. Monitors may be provided to monitor the current and / or voltage of the various low voltage supplies and to enable / disable the control and discharge circuits.

[0087] The RFTH module may include a Board Module Controller (BMC) 3019 that provides a communication interface with the system real-time controller (RTC) and receives data from the power measurement system 3007, the on-board health monitoring system, and the power supply monitoring system. The BMC 3019 may be configured to generate a fault whenever it detects an erroneous reading from the health monitoring system. Such faults may be reported to the RTC and logged to an on-board EEPROM device. The BMC 3019 may be programmed via a JTAG header 3021 or by a JTAG interface to the RTC.

[0088] The RFTH module can be configured to connect to the backplane of the controller 300 via a PCIe connector. Control of the power amplifier 3001 can be performed directly by the RTC via this PCIe connector. The RTC controls the amplitude of each channel and controls the frequency and phase via the control of the DDS. The IC on the board is powered by a buck converter DC-DC power supply and a low dropout regulator, which is powered by a 24VDC main power supply. In various embodiments, a separate 39VDC power supply may be included to provide power to the power amplifier. In various embodiments, this separate power supply can be enabled and disabled separately. Various innovative aspects of different components, circuits and / or subsystems of the RFTH module are described in more detail below. Power Amplifier

[0089] Various embodiments of the power amplifier covered by the present application are capable of efficiently providing up to 100 W of RF power within a frequency range from 1.0 MHz to 12.0 MHz. For example, various embodiments of the power amplifier included in the RFTH module may be configured to provide an RF output power in the following range: between about 1 W and about 10 W, between about 5 W and about 15 W, between about 10 W and about 20 W, between about 25 W and about 35 W, between about 30 W and about 40 W, between about 35 W and about 45 W, between about 40 W and about 50 W, between about 45 W and about 55 W, between about 50 W and about 60 W, between about 55 W and about 65 W, between about 60 W and about 70 W, between about 65 W and about 75 W, between about 70 W and about 80 W, between about 75 W and about 85 W, between about 80 W and about 90 W, between about 85 W and about 95 W, between about 90 W and about 100 W, or any RF output power in any range / sub-range defined by any of these equivalent values. In some embodiments, the power amplifier may be configured to provide an RF output power greater than about 100 W.

[0090] Various embodiments of the power amplifier 3001 included in the RFTH module can be configured to operate within a wideband frequency tuning range. For example, various embodiments of the power amplifier can be configured to provide up to 100W of RF output power within a frequency range spanning at least 2 octaves. For example, the power amplifier can be configured to provide RF output power in any range / sub-range defined by values ​​between about 1W and about 100W within the following frequency broadband ranges: between about 1.0 MHz and about 5 MHz, between about 2.5 MHz (e.g., 2.0 MHz, 2.2 MHz, 2.4 MHz, 2.6 MHz, 2.8 MHz, 3.0 MHz) and about 7.5 MHz (e.g., 7.0 MHz, 7.2 MHz, 7.4 MHz, 7.6 MHz, 7.8 MHz, 8.0 MHz), between about 3.0 MHz (e.g., 2.5 MHz, 2.6 MHz, 2.8 MHz, 3.0 MHz) and about 7.5 MHz (e.g., 7.0 MHz, 7.2 MHz, 7.4 MHz, 7.6 MHz, 7.8 MHz, 8.0 MHz), between about 3.0 MHz (e.g., 2.5 MHz, 2. The power amplifier may be configured to operate at an efficiency of at least 75% at different frequencies in a frequency range / sub-range defined by values ​​between about 1.0 MHz and about 12.0 MHz.

[0091] Various embodiments of the power amplifier 3001 included in the RFTH module can be configured to provide reliable operation by preventing short circuit and open circuit conditions. Various embodiments of the power amplifier included in the RFTH module can be optimized to drive a 50Ω load. Various embodiments of the power amplifier included in the RFTH module can be configured to drive a load having an impedance between about 20Ω and about 200Ω and a phase between about -60 degrees and about 60 degrees. For example, various embodiments of the power amplifier can be configured to drive a transducer having an impedance in the range of 20Ω and 120Ω with a phase angle between +45 degrees and -45 degrees. Semiconductor material (e.g., GaN) field effect transistor

[0092] It is desirable for the power amplifier 3001 to achieve a power efficiency greater than about 75% over a range of operating frequencies between 1.0 MHz and 12.0 MHz. Therefore, various embodiments of the power amplifier 3001 may have a switch-mode design. Switch-mode amplifiers may be classified as resonant devices with zero voltage switching (e.g., class E) or devices without zero voltage switching (e.g., class D). Many embodiments of the power amplifier 3001 described in this application that are configured to operate over a frequency range between 1.0 MHz and 12.0 MHz use a non-resonant switch-mode amplifier design. One implementation of the switch-mode amplifier includes a switching circuit and a low-pass filter. The output of the switch-mode amplifier is a square wave. After passing through the low-pass filter, the square wave becomes closer to a sine wave because harmonics above the cutoff frequency of the low-pass filter are removed. Most conventional metal-oxide-semiconductor (MOS) field effect transistors (FETs) comprising silicon may not be able to achieve a power efficiency greater than 75% over the desired operating frequency range between 1.0 MHz and 12.0 MHz. However, electronic devices (e.g., transistors and / or FETs) including high-efficiency transistors such as III-V semiconductor materials (e.g., III-V compound semiconductors obtained by combining Group III elements (e.g., Al, Ga, In) and Group V elements (e.g., N, P, As, Sb), such as gallium nitride (GaN), gallium arsenide (GaAs), gallium antimonide (GaSb), indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), indium gallium arsenide (InGaAs), aluminum antimonide (AlSb), aluminum gallium arsenide (AlGaAs), aluminum gallium nitride (AlGaN), etc.) have output capacitance and switching time that are about an order of magnitude lower than the output capacitance of silicon MOSFETs at a given operating voltage. In several embodiments, GaN transistors are described, but in other contemplated embodiments, any of GaN, GaAs, GaSb, InP, InAs, InSb, InGaAs, AlSb, AlGaAs, and / or AlGaN transistors may be used. In one embodiment, only one semiconductor is used. Thus, GaN FETs are capable of achieving power efficiencies greater than about 75% within a frequency range between about 1.0 MHz and 12.0 MHz.GaN FETs include a thin GaN layer grown on a silicon wafer.GaN FETs may have several advantages, including but not limited to (i) high dielectric strength, which may be due to GaN being a wide bandgap semiconductor; (ii) high operating temperature, which may be due to GaN being a wide bandgap semiconductor and / or having a high potential barrier; (iii) high current density, which may be due to high electron mobility; (iv) high speed switching, which may be due to high electric field saturation velocity and high electron mobility; (v) low on-resistance compared to traditional silicon (Si) devices, which may be due to high electron mobility; and (vi) low output capacitance compared to traditional Si devices, which may also be due to high electron mobility. For example, for the same current handling capability as a silicon FET, a FET made of GaN may exhibit input and output capacitance that is approximately ten (10) times lower. This feature may allow GaN FETs to operate efficiently at much higher frequencies than silicon FETs. Thus, GaN FETs may be able to achieve greater than approximately 75% power efficiency in a switch-mode RF amplifier over a desired operating frequency range between 1.0 MHz and 12.0 MHz. Transmission Line Transformers

[0093] The GaN FET may have a low output impedance (e.g., less than 100 mΩ). The RFTH module including the GaN FET is configured to drive one or more ultrasonic transducers that present an impedance having a magnitude between 20Ω and 200Ω (e.g., 50Ω impedance) to the RFTH module. In various embodiments of the RFTH module, a transmission line transformer is used to match the input impedance of the GaN FET with the impedance presented by the one or more ultrasonic transducers. Figure 4 Describes an implementation of a transmission line transformer that can be used to match the impedance of a GaN FET to the impedance presented by one or more ultrasonic transducers. Figure 4 The implementation of the transmission line transformer in is a Guanella type transmission line with a 4:1 impedance ratio. The transmission line transformer includes a set of common mode chokes 4001a, 4001b, 4001c and 4001d connected in parallel on the low impedance side (e.g., the side facing the GaN FET device 4005) and connected in series on the high impedance side (e.g., the side facing the load 4003). The common mode chokes 4001a to 4001d may include wires wound on an iron core. The output has an output voltage V gThe positive current 2I of the power amplifier 3001 is branched into a current I flowing through the common-mode choke 4001d and a current I flowing through the common-mode choke 4001b. The common-mode choke is configured to allow only differential signals to pass. Therefore, the positive current in the common-mode choke 4001b generates a negative current -I in the common-mode choke 4001a, which returns to the current in the common-mode choke 4001d. Because the current 2I flows into the left side of the transmission line transformer and the current I flows through the load 4003, according to the law of conservation of energy, the voltage on the load 4003 must be 2V g This is the basic operating principle of the Guanella transmission line transformer.

[0094] Depicted on Figure 4 An implementation of the Guanella transmission line transformer in provides a 2:1 turns ratio, which produces a 4:1 impedance ratio. A higher impedance ratio can be achieved by adding more common mode chokes in parallel on the left side and in series on the right side. In addition, the common mode chokes do not need to be on different cores. The windings can all be wound on the same core as long as proper attention is paid to the winding direction to ensure that the common mode magnetic fields from different winding pairs are not cancelled. Various embodiments of the power amplifier 3001 include a Guanella transmission line transformer having three (3) pairs of windings on a single Amidon FT-87A-43 core. The three (3) pairs of windings may include bifilar windings that can advantageously minimize or reduce parasitics. In addition, each pair of bifilar windings may present a large common mode impedance and a small differential mode impedance. This embodiment of the Guanella transmission line transformer can provide a 9:1 impedance ratio that transforms a 50Ω output impedance into a 5.6Ω impedance at the transistor. By transforming the nominal 50Ω load impedance to 5.6Ω on the side facing the GaN FET, embodiments of the Guanella transmission line transformer can provide a load that the GaN FET can drive more efficiently than it could directly drive a 50Ω load. This may be due to the quadratic increase in output capacitor charging losses experienced as voltage increases. Additionally, by boosting the output voltage, embodiments of the Guanella transmission line transformer can allow large output voltages in excess of 200Vpp to be generated from a low voltage power supply (e.g., nominally 39VDC).

[0095] In addition, by providing balanced to unbalanced conversion, the Guanella transmission line transformer can allow the use of a balanced H-bridge driver to drive an ultrasonic transducer with a ground reference signal. The balanced H-bridge design provides effective multiplication of the drive voltage and, due to the left-right symmetry of the bridge, even harmonics can be eliminated from the output waveform. The balanced H-bridge driver design is discussed in detail below. H-Bridge Driver

[0096] Various embodiments of power amplifier 3001 including GaN FETs can be driven by an H-bridge driver. The H-bridge design topology is described in Figure 5A The H-bridge is operated by placing a load 5003 at the midpoint between a first pair of FETs 5001a and 5001b and a second pair of FETs 5001c and 5001d. The diagonally opposite FETs on the bridge (e.g., 5001a and 5001d or 5001b and 5001c) are configured to switch to the same state. In a first switching configuration, FETs 5001a and 5001d are configured to be in a closed configuration, while FETs 5001b and 5001c are configured to be in an open configuration, such as Figure 3A and 3B In the first switching configuration, current is driven from left to right through the load 5003. In the second switching configuration, FETs 5001b and 5001c are configured to be in a closed configuration, while FETs 5001a and 5001d are configured to be in an open configuration, as shown in FIG. Figure 3A and 3B In the second switching configuration, the current is driven from right to left through the load 5003. Due to the left-right symmetry of the H-bridge design, the negative portion of the signal can have substantially the same form as the positive portion of the signal. This property can advantageously suppress even harmonics in the signal, leaving only odd harmonics.

[0097] The H-bridge driver design is optimized to achieve an average power efficiency greater than about 75% over a frequency range between about 1.0 MHz and 12.0 MHz. For example, the average power efficiency achieved by various embodiments of the power amplifier 3001 including GaN FETs may be greater than about 80%, greater than about 85%, greater than about 90%, greater than about 95%, and / or less than about 100% over a frequency range between about 1.0 MHz and 12.0 MHz. The optimized H-bridge design may be configured to achieve a peak power efficiency greater than about 85% over a frequency range between about 1.0 MHz and 12.0 MHz. For example, the average power efficiency achieved by various embodiments of the power amplifier 3001 including GaN FETs may be greater than about 90%, greater than about 95%, and / or less than about 100% over a frequency range between about 1.0 MHz and 12.0 MHz.

[0098] The functional requirement of the ultrasonic therapy system 20 described herein is to generate an output signal that is instantaneously narrow-band but can operate at any frequency within a wide range spanning at least 2 octaves (e.g., spanning at least 3 to 4 octaves). For example, the ultrasonic therapy system 20 described herein can be configured to generate an output signal at a fundamental frequency f0 having a value within a frequency range between 1.0 MHz and 12.0 MHz and having a bandwidth (e.g., 3 dB bandwidth) of the output signal. Without relying on any particular theory, the output from the H-bridge driver is a filtered square wave that includes a signal component at the fundamental frequency f0 and a component at higher harmonics. Higher harmonics can distort the RF signal output from the power amplifier 3001 and / or also affect the measurement accuracy of the RF power of the output RF signal. In addition, if one or more ultrasonic transducers are driven by a signal containing harmonics, the acoustic emission may also contain harmonics. Because of the frequency dependence of ultrasound absorption in tissue, this can result in heating close to the intended focal point, which can be hazardous to the patient. In addition, harmonics at frequencies above 30 MHz may present a risk of generating radiated emissions that exceed the limits set by the basic safety and performance of medical devices.

[0099] Therefore, it is necessary to reduce the amplitude of the higher harmonics in the signal output from the H-bridge driver to below the threshold value. One method of reducing the amplitude of the higher harmonics in the signal output from the H-bridge driver may include providing a low-pass filter to remove the higher harmonics. However, providing a low-pass filter that filters out higher harmonics with a lower frequency f0 value (e.g., between 1.0 MHz and about 6.0 MHz) may result in reducing the amplitude of the output RF signal having a fundamental frequency f0 greater than the cutoff frequency of the low-pass filter. Therefore, in order to allow the power amplifier 3001 to operate efficiently over the entire frequency range of 1.0 MHz to 12.0 MHz, the cutoff frequency of the low-pass filter should be greater than about 12.0 MHz, such as 16.0 MHz. However, a low-pass filter having a cutoff frequency greater than about 12.0 MHz is not able to attenuate the amplitude of higher harmonics with a lower frequency f0 value (e.g., between 1.0 MHz and about 6.0 MHz). Therefore, when the power amplifier 3001 is configured to operate at a fundamental frequency f0 having a value between about 1.0 MHz and about 6.0 MHz, multiple higher harmonics may be present in the passband.

[0100] As discussed above, the H-bridge design uses an inversely symmetrical waveform where the negative portion of the waveform looks like the positive portion of the waveform to eliminate high even harmonics (e.g., signals at 2f0, 4f0, 6f0 or other high even harmonics). To suppress high odd harmonics (e.g., signals at 3f0, 5f0, 7f0 or other high odd harmonics), the H-bridge design uses a unique drive signal scheme where the duty cycle of the positive portion of the waveform and the negative portion of the waveform are selected to suppress the high odd harmonics. Figure 6 The driving signal generated by the H-bridge is shown when the duty cycle of the positive portion of the waveform and the negative portion of the waveform is set to 0.3. Figure 7 Shows how the amplitude of the higher odd harmonics changes for different duty cycles of the positive and negative parts of the waveform. Figure 7 Note that the fundamental power increases with the duty cycle, reaching its peak at 50% duty cycle. Therefore, the duty cycle can be used to modulate the output power at the fundamental frequency. Figure 7 It is further noted that different harmonics reach their minimum values ​​at different duty cycle values. Thus, if suppression of a particular harmonic is desired, there are one or more duty cycle values ​​for which that harmonic is suppressed to a large extent. Furthermore, at a duty cycle of 0.333, both the 3rd and 9th harmonics are suppressed. This suppression is useful because the 3rd harmonic is the lowest frequency non-zero harmonic and is therefore likely to be suppressed the least by the low pass filter. Thus, selecting a duty cycle of approximately 0.3 can advantageously suppress the 3rd harmonic in the drive signal. Without any loss of generality, the duty cycles of the positive and negative portions of the waveform are selected to have the same value to suppress even harmonics. Figure 7 It is further noted that the minimum total harmonic content occurs at a duty cycle of 0.386. In addition to controlling the duty cycle of the positive portion of the waveform and the negative portion of the waveform output from the H-bridge to suppress high odd harmonics, a low pass filter having a cutoff frequency greater than or equal to about 80% of the maximum operating frequency of the power amplifier may also be provided to suppress high odd harmonics. For example, in various embodiments of an ultrasound therapy system configured to operate at a maximum frequency of about 12.0 MHz, a low pass filter having a cutoff frequency greater than or equal to about 12.0 MHz (e.g., between about 10 MHz and about 16.0 MHz) may be used to remove high odd harmonics having frequencies greater than the cutoff frequency.

[0101] Consider an embodiment of an ultrasound therapy system configured to operate in a frequency range of about 1.0 MHz to about 12.0 MHz. Additionally, consider that the GaN FETs in the power amplifier included in this embodiment of the ultrasound therapy system are driven by an H-bridge driver, wherein the duty cycle of the positive portion of the waveform and the negative portion of the waveform are selected to suppress the 3rd harmonic (e.g., a duty cycle of about 0.33). Further consider that the power amplifier includes a low pass filter having a cutoff frequency of about 16 MHz (e.g., a 5th order Chebyshev filter with 0.1 dB ripple). FIG. 8A to FIG. 8D The signals output from this implementation of a power amplifier are shown at 2.0 MHz, 4.0 MHz, 7.0 MHz, and 12.0 MHz. FIG. 8A to FIG. 8D , reference numerals 8001a, 8003a, 8005a, and 8007a refer to output signals before the low-pass filter, and reference numerals 8001b, 8003b, 8005b, and 8007b refer to output signals after the low-pass filter. It should be noted that Fig. 8A The output signal after the low pass filter is distorted from the sinusoidal shape, which indicates that the low pass filter allows some high odd harmonics to exist in the passband at a frequency of 2.0 MHz. At a frequency of 4.0 MHz, the contribution of the high odd harmonics is significantly reduced, as shown in Figure 1. Figure 8B At frequencies of 7.0 MHz and 12.0 MHz, the high odd harmonics are nearly eliminated, as indicated by the sinusoidal nature of the signal output after the low pass filter.

[0102] Thus, various embodiments of an H-bridge driver configured to drive the GaN FETs of power amplifier 3001 are configured to operate at a duty cycle that suppresses the 3rd harmonic and causes the low pass filter to have a cutoff frequency designed to suppress high odd harmonics having frequencies greater than approximately 12.0 MHz.

[0103] The H-bridge drive signal is generated by comparison between a DC signal set by a digital-to-analog converter (DAC) and a pair of out-of-phase sine wave signals from a balanced differential output stage of a direct digital synthesizer (DDS). Fig. 9 A simplified schematic diagram showing a comparator circuit used to generate two drive waveforms. Fig. 9 In FIG. 9 , battery 9001 represents a DC voltage source and transformer 9003 provides a balanced signal.

[0104] Fig.10The H-bridge drive signals are graphically shown plotted on the same plot, with waveform 10001a depicting a waveform generated by an in-phase sine wave and 10001b depicting a waveform generated by an out-of-phase sine wave. The two drive signals represented by waveforms 10001a and 10001b are delayed by 180 degrees.

[0105] Depend on Fig. 9 An advantage of the H-bridge design represented by the circuit is that it can provide a convenient mechanism for modulating the gate drive duty cycle by changing the value of the DC signal corresponding to the output from the battery 9001. In the RFTH module, this DC signal is controlled by a 12-bit DAC and the duty cycle can be modulated from 0% to 50%. As discussed above, control of the duty cycle provides several advantages, including but not limited to adjusting the power level of the fundamental frequency and suppressing the amplitude of higher harmonics. In addition, setting the gate drive duty cycle to 0% or 100% can provide a convenient method to prevent the H-bridge FET from being cut off during the TCP used to measure VSWR sensitivity. In addition, setting the gate drive duty cycle to 0% or 100% can provide a mechanism to disable unused channels during testing. Protection Circuit

[0106] Fig.11A A simplified circuit diagram illustrating a switch mode power amplifier 3001 including an H-bridge formed of four (4) GaN FETs 11001a, 11001b, 11001c and 11001d driving the balanced side of a 1:9 Guanella transmission line transformer 11003. GaN FETs can be easily damaged by inductive spikes due to their relatively fragile gate channel insulation and small range of breakdown voltages. Therefore, a protection circuit including parallel 5.6V Zener diodes 11005 and fast Schottky diodes 11007 on the H-bridge high side FET gates 11001c and 11001d ensures that the threshold turn-on voltage V GS The positive side does not exceed 5.6V and the gate is no more than 0.3V below the source on the negative side. The implementation of this protection circuit is shown in Fig. 11B This protection circuit can protect the GaN FET from inductive spikes and can withstand short-circuit surges (or discharges) exceeding 20A for more than 1ms (e.g., 2ms, 5ms, 10ms, or more than 10ms). For example, Schottky diode 11007 can ensure that the negative V GS In the event of an inductive spike, the gate voltage remains clamped to the source voltage. In some embodiments, in the absence of Schottky diode 11007, current surges exceeding 8A (such as might be encountered in a short circuit event) can cause the GaN FET to fail. Amplitude control

[0107] Various embodiments of power amplifier 3001 may include a voltage-controlled buck converter to provide amplitude control. An implementation of a voltage-controlled buck converter is shown in Fig. 11C and Fig.11D In. The voltage-controlled buck converter may also be referred to as a feedback-controlled buck converter. The amplitude may be controlled by injecting current into a summing node of the voltage-controlled buck converter, which applies a step-wise and / or low-bandwidth modulation (or modulation) (e.g., less than or equal to about 3kHz) to the output of the voltage-controlled buck converter. In one embodiment, the deployed system uses discrete amplitude changes. In one embodiment, discrete amplitude changes are critical to controlling power for any therapy mode-imaging mode scenario. A low-bandwidth modulated output from the voltage-controlled buck converter is provided to an H-bridge, which enables the RF power output from the power amplifier to have a low-bandwidth modulation. Without loss of any generality, the low-bandwidth modulated output from the voltage-controlled buck converter may change the drive voltage provided to the FET, which may change the voltage applied to the load when the high-side FET is turned on. This scenario is described in further detail below.

[0108] In one embodiment, the H-bridge output is modulated by changing the voltage supplied at the drain of the high-side FET that is delivered to the load when the high-side FET is turned on. In one embodiment, the H-bridge output is modulated by changing the voltage supplied at the drain of the high-side FET that is delivered to the load when the high-side FET is turned off. In some embodiments, this voltage is generated as an output from a step-down DC-DC buck converter that is capable of efficiently stepping down the voltage from the high-voltage power supply. The output voltage of the buck converter is controlled by the duty cycle and frequency of the switching event. Some embodiments of the basic buck converter circuit include a feedback loop in which the output is measured and compared to a threshold value. If the output drops below the threshold value, the buck converter modifies its switching behavior to deliver more power to the load. In some embodiments of a power amplifier using a buck converter to set the output amplitude, the output of the buck converter is controlled by injecting current into the summing input of the feedback loop. As more current is delivered to the summing node, the output of the buck converter will provide less current, which causes the output voltage to drop. Conversely, as less current is delivered to the summing node, the output of the buck converter will provide more current, which causes the output voltage to rise. The voltage at the output of the buck converter may rise until the voltage at the summing node exceeds a threshold. Power Measurement System

[0109] As discussed above, various embodiments of the RFTH module described herein include a power measurement system 3007 configured to monitor the electrical power output from the power amplifier 3001 to one or more ultrasonic transducers. In various embodiments, the power measurement system 3007 can be configured to measure the power of the RF signals output from the power amplifiers in different drive subsystems 3000 of the RFTH module. In addition, the power measurement system 3007 can also be configured to measure the relative phase between the RF signals output from the power amplifiers 3001 of different drive subsystems 3000.

[0110] The power measurement system 3007 can be implemented as a high-density printed circuit board (PCB) design. The PCB design can be configured to have a small size and / or low heat dissipation. Various embodiments of the power measurement system 3007 can be configured to measure the RF signal power output from the power amplifier 3001 delivered to a wide range of load impedances Z, the load impedance having a magnitude |Z| between 20Ω and 200Ω and a phase angle ∠Z between -60° and 60°. For example, various embodiments of the power measurement system 3007 can be configured to measure the RF signal power output from the power amplifier 3001 delivered to a wide range of load impedances Z, the load impedance having a magnitude |Z| between 20Ω and 120Ω and a phase ∠Z between +45 degrees and -45 degrees. Various embodiments of the power measurement system 3007 can be configured to measure the power of the RF signal output from the power amplifier of different drive subsystems 3000 with an accuracy of approximately ±0.5dB. Various embodiments of the power measurement system 3007 can be configured to measure the power of the RF signal output from the power amplifier in the different driving subsystems 3000 with an accuracy of about ±0.5 dB even in the case where high-order harmonics contribute significantly to the RF signal power. Various embodiments of the power measurement system 3007 can be configured to operate over a wide frequency range. For example, the power measurement system 3007 can be configured to operate over at least the same frequency range as the power amplifier 3001. For example, the power measurement system 3007 can be configured to operate over a wide frequency range between about 1.0 MHz and about 12.0 MHz.

[0111] Various embodiments of the power measurement system 3007 may include resistive current sensing and voltage sensing components. For example, various embodiments of the power measurement system 3007 may use a small signal transformer for common mode rejection. Using resistive current sensing and voltage sensing components may have several advantages over more commonly used magnetic devices for monitoring RF power (e.g., RF directional couplers, RF circulators, and other magnetic devices), including but not limited to smaller circuit size, lower cost, lower heat dissipation, and / or improved interference immunity.

[0112] Although parasitic reactance effects can be significant in resistive current sensing and voltage sensing components, most parasitic reactance effects can be calibrated out and removed from the measurement. The power measurement system 3007 may include a differential measurement scheme that includes a wideband small signal RF transformer, such as Fig.12 . The differential measurement scheme can remove large common-mode components from the signal and can advantageously isolate the measurement circuit system from the current sensing resistor 12001. The differential measurement scheme can resist interference caused by capacitive and magnetic coupling between components of the power measurement system 3007 and components of the power amplifier 3001. In particular, the magnetic field radiated from the power transformer and the parasitic mutual capacitance and inductance on the PCB can couple to the amplifier input. This interference is common-mode and will produce almost the same coupling on the two inputs of the differential amplifier. Therefore, using a differential amplifier can advantageously subtract / remove the common-mode coupling at the two inputs of the differential amplifier while enhancing the differential current or voltage signal.

[0113] The power measurement system 3007 includes a heterodyne IQ demodulator (e.g., a demodulator AD8333 from Analog Devices). In various embodiments of the RFTH module, each driver subsystem 3000 may include a heterodyne IQ demodulator configured to receive sampled current and voltage waveforms of a portion of the RF signal output from the power amplifier included in that driver subsystem 3000.

[0114] Fig.13 The implementation scheme of the power measurement system 3007 is shown. Fig.13 , a portion of the output from the power amplifier 3001 is measured by resistive current sensing and voltage sensing components configured in a differential measurement scheme shown in block 13003. The output from the resistive current sensing and voltage sensing components in block 13003 is input into a heterodyne IQ demodulator 13000. The heterodyne IQ demodulator 13000 includes a local oscillator (LO) clock 13001; current demodulator components 13005a and 13005b; voltage demodulator components 13005c and 13005d; filtering components 13007a, 13007b, 13007c, and 13007d; and analog to digital converters (ADCs) 13009a, 13009b, 13009c, and 13009d. The heterodyne IQ demodulator 13000 is configured to operate at any frequency.

[0115] The heterodyne IQ demodulator 13000 can provide magnitude and phase measurements of the RF signal output from the power amplifier 3001. The heterodyne IQ demodulator 13000 can be configured to make measurements at a baseband where the measurements may not be interfered with. The heterodyne IQ demodulator 13000 can include a high bit depth and slow sampling rate ADC that can potentially reduce cost, improve accuracy, and permit multiplexing of different RF channels. The low pass filter of the IQ demodulator 13000 can allow narrow band filtering that can be independent of the frequency of the RF signal that can span a wide bandwidth range.

[0116] Fig.14 A block diagram of an AD8333 IQ demodulator from Analog Devices is shown. The IQ demodulator 13000 is configured to mix and downsample the sampled current and voltage waveforms to a baseband frequency so that they can be digitized with a high resolution analog-to-digital converter (e.g., ADCs 13009a to 13009d). The IQ demodulator can be configured to demodulate the input signal in a phase-sensitive manner so that the phase of the RF signal relative to a reference clock can be faithfully reproduced as the phase of the analysis signal, whose real and imaginary components are the two outputs of the IQ demodulator in a narrow band limit.

[0117] The IQ demodulator 13000 is a dual channel device that accepts two input RF signals and an input from a local oscillator (LO) clock 13001. To demodulate to baseband, the frequency of the LO 13001 is four (4) times the frequency of the RF signal. For example, if the power amplifier 3001 is operating at a frequency f0 having a value between 1.0 MHz and 12.0 MHz, the frequency of the LO 13001 is 4f0.

[0118] The IQ demodulator 13000 uses input from the LO clock 13001 to generate two internal LO clocks running at f0. The first internal clock may be referred to as the I clock and the second internal clock may be referred to as the Q clock. In one embodiment, the two internal LO clocks may be obtained by digitizing the LO clock and using it to run two divide-by-four logic circuits, each of which triggers on every fourth rising edge of the input LO clock, but where the Q clock is delayed by one cycle of the input LO clock relative to the I clock.

[0119] Fig.15 Two internal clocks generated by an implementation of demodulator 13000 are shown. Fig.15 , waveform 15001 shows the signal output from power amplifier 3001, waveform 15003 shows the output of LO clock 13001, waveform 15005 shows the I clock and waveform 15007 shows the Q clock. The I clock and Q clock can be used to demodulate and reconstruct the signal output from power amplifier 13000, as discussed below.

[0120] The demodulator works by making the I and Q clocks control whether the power amplifier 3001 that amplifies the RF signal is inverted. This operation is equivalent to multiplying the RF signal output from the power amplifier 3001 by a square wave with a maximum value of 1 and a minimum value of -1, such as Fig.16 As shown in .

[0121] This operation produces two output signals, one for the I clock and the other for the Q clock. For a sinusoidal signal in phase with the I clock, mixing with the I clock produces a signal with a positive mean. On the other hand, mixing with the Q clock produces a signal with a mean of zero. Fig.17 Shows I and Q demodulation of a sinusoidal signal. Fig.17 In the figure, signal 17001 is the output of the sinusoidal signal mixed with the I clock, and 17003 is the output of the sinusoidal signal mixed with the Q clock.

[0122] The mean of the mixed signal is only its fundamental frequency value and can be extracted by low pass filtering. In the case of narrow band signals like sine waves, the I and Q outputs are the real and imaginary parts of the analytical signal, with the phase of the analytical signal is the phase difference between the RF input signal and the local oscillator and its magnitude Proportional to the amplitude of the RF signal.

[0123] The IQ demodulator uses a phase-shift harmonic cancellation scheme that allows the magnitude and phase of the fundamental frequency component to be measured in the presence of higher harmonics. In the phase-shift harmonic cancellation scheme, the heterodyne LO clock 13001 is discretely phase-shifted relative to the RF signal output from the power amplifier 3001 to produce a set of LO phase-dependent IQ samples. The samples are reconstructed into fundamental and harmonic powers using linear inversion. This is described in more detail below.

[0124] As discussed above, power amplifier 3001 is configured to operate over a wide frequency range spanning at least two (2) octaves. For example, as discussed above, power amplifier 3001 is configured to operate over a wide frequency range of about 1.0 MHz to about 12.0 MHz. To allow wideband operation of power amplifier 3001, the low pass filter may have a cutoff frequency greater than or equal to about 16 MHz. Thus, higher harmonics of lower operating frequencies (e.g., operating frequencies between about 1.0 MHz and about 6 MHz) will be in the passband of the low pass filter and therefore cannot be filtered out without affecting the bandwidth of power amplifier 3001. As an example of this, Fig.18A shows an oscilloscope trace of the output from the power amplifier 3001 into a 10 to 100 ohm (e.g., 25 ohm, 50 ohm, 75 ohm) load operating at an operating frequency of approximately 1.0 MHz, and Fig.18BOscilloscope traces are shown of the output from power amplifier 3001 into a 50 ohm load operating at an operating frequency of approximately 12.0 MHz. Traces 18001a and 18001b show the output waveforms at the two operating frequencies, respectively. At 12.0 MHz, all higher harmonics are above the cutoff frequency of the low pass filter (e.g., 16 MHz) and therefore the output waveform is a pure sine wave. However, at 1.0 MHz, some harmonics are in the passband and therefore the waveform is non-sinusoidal. The presence of higher harmonics may affect the accuracy of measuring the amplitude and phase of the output RF signal, as discussed in detail below.

[0125] Because of the presence of harmonics, the output from power amplifier 3001 cannot be considered narrowband. In fact, the output from power amplifier 3001 consists of the sum of several narrow bands with frequencies centered around harmonic n×ω0, where n is an integer and ω0 is the fundamental frequency.

[0126] Therefore, the RF signal at the output of the power amplifier 3001 can be described as the Fourier decomposition given by the following equation (1): Where An and Bn are the in-phase and quadrature components of each of the harmonics of the signal.

[0127] As will be discussed in detail below, the power guarantee circuit configured to measure the amplitude and phase of the RF signal output from the power amplifier includes an IQ demodulator. Without relying on any particular theory, the role of the IQ demodulator can be viewed as multiplying the RF output from the power amplifier 3001 by a square wave, followed by low pass filtering. The square wave contains a signal component at a fundamental frequency and a signal component at harmonics of the fundamental frequency, and can be described as the Fourier decomposition given by the following equation (2):

[0128] Whenever both the RF output from power amplifier 3001 and the square wave signal have harmonic components, multiplication will mix the harmonic components to the fundamental frequency, that is, the difference frequency will be 0 Hz. Fig.19A and Fig.19B The magnitude of the Fast Fourier Transform (FFT) of the RF signal at the low frequency end of the passband (normalized to a fundamental frequency of 1 MHz) and the magnitude of the Fast Fourier Transform (FFT) of the square wave are shown. Fig.19A and Fig.19B , waveform 19001 shows the FFT of the RF signal, and waveform 19003 shows the FFT of the square wave. Fig.19A and 19BNote that there are fundamental, fifth, and seventh harmonics of the RF signal. The square wave has significant components at all odd harmonics. Harmonics of both the square wave and the RF signal that have non-zero magnitudes in the FFT will contribute to the measured fundamental frequency signal.

[0129] The IQ demodulator of the power guarantee circuit can be considered to have I and Q local oscillators. The outputs from the I and Q local oscillators can be considered as square waves. Therefore, the outputs from the I and Q local oscillators can be Fourier decomposed as presented in equations (3a) and (3b). where the equation for q(t) is obtained by shifting i(t) by a quarter cycle, i.e., replacing Replace t.

[0130] After mixing and low pass filtering, the harmonics in both the I and Q local oscillators and the RF signal will contribute to the I and Q baseband signals as presented in equations (4a) to (4d).

[0131] Therefore, the fundamental signal depends not only on the Fourier amplitude at the fundamental frequency, but also on all non-zero odd harmonics in the RF signal.

[0132] Therefore, when harmonics are present, the measured I and Q values ​​may not return the correct phase value or amplitude. In addition, because of the harmonics, the measured signal amplitude may depend on the phase between the I and Q local oscillators and the RF signal. This can introduce systematic errors that can change as the beamforming delay changes. The beamforming delay may include a phase delay introduced between different channels in order to obtain the desired focusing effect from the multi-element transducer. For example, the error associated with this effect can be as high as 6% for the amplitude of the voltage and current, and + / - 3 degrees for the phase. This can result in significant inaccuracies in the measured voltage and / or phase.

[0133] For example, one method of reducing inaccuracies in the measured voltage and / or phase of the output RF signal from the power amplifier 3001 includes correcting the amplitude and phase of the portion of the RF signal output from the power amplifier 3001 received at the power guarantee circuit 3007 to remove the effects of harmonics. The amplitude and phase of the portion of the RF signal output from the power amplifier 3001 received at the power guarantee circuit 3007 are corrected by acquiring I and Q data at multiple phase shifts of the I and Q clocks relative to the portion of the RF signal output from the power amplifier 3001 received at the power guarantee circuit 3007. Collecting I and Q data measured at N different phase offsets is sufficient to eliminate the contribution of the first N harmonics, but more measurements can be used to obtain a better estimate of the harmonics in the presence of noise. In many embodiments, if six (6) different phase offsets are measured, the effects of the harmonics can be reduced to a level below the system noise floor.

[0134] Therefore, one method of reducing the effects of harmonics includes measuring I and Q data for internal I and Q clock phases at 0°, 15°, 30°, 45°, 60°, and 75° relative to the portion of the RF signal output from the power amplifier 3001 received at the power guarantee circuit 3007. In some embodiments, the input local oscillator (LO) frequency included in the power guarantee circuit 3007 may have a frequency that is four (4) times the internal frequency. Therefore, the phase of the input LO clock may be a phase that is greater than four times the phase of the I and Q clocks. For example, when the I and Q clock phases are 0°, 15°, 30°, 45°, 60° and 75° relative to the portion of the RF signal output from the power amplifier 3001 received at the power guarantee circuit 3007, the phase of the input LO clock may be 0°, 60°, 120°, 180°, 240° and 300° relative to the portion of the RF signal output from the power amplifier 3001 received at the power guarantee circuit 3007.

[0135] Fig. 20 Six (6) phase shift sets of I and Q clocks used to demodulate the non-sinusoidal drive signal according to the method discussed above are illustrated. After mixing, the demodulator outputs twelve (12) signals that can be used to reconstruct the RF signal output from the power amplifier 3001, such as Fig.21 As shown in .

[0136] The relationship between the measured I and Q values ​​at these different phases and the correct Fourier amplitude of the signal at each harmonic is linear, and thus the Fourier amplitude of the RF input signal can be obtained from the measured I and Q samples at the six phases via matrix multiplication.

[0137] Since I and Q are quadrature components, if the I samples are taken at a set of 6 phases (e.g., 0°, 15°, 30°, 45°, 60°, 75°) equally distributed in a range between 0° and 75° in 15° steps, the Q samples will be phase shifted 90° from the I samples. For example, the Q samples will be at 90°, 105°, 120°, 135°, 150°, 165°.

[0138] Utilizing the inversion symmetry of the signal, the signal output from the power amplifier 3001 can be described by the following equation (5). Where T0 = 1 / f0 is the period. The entire period of the signal can be expressed based on the I and Q phase shift signals as: {I0,I 15 ,…,I 75 ,Q0,Q 15 , …Q 75 ,-I0,-I 15 ,…,-I 75 ,-y0,-Q 15 ,…-Q 75} Among them I n is the I sample at n° phase shift, and Q n is the Q sample at n° phase shift. It should be noted that due to inversion symmetry, Q 180 Equal to Q0.

[0139] Therefore, six (6) phases spanning the range of 0° to 180° are sufficient to reconstruct the RF signal output from power amplifier 3001.

[0140] According to inversion symmetry, only odd Fourier components will be non-zero. Therefore, the first, third, fifth, seventh, ninth, and eleventh harmonics will be non-zero. Therefore, in order to reconstruct the RF signal output from the power amplifier 3001, the discrete Fourier transform (DFT) coefficients for the non-zero odd harmonics are calculated. In one method of reconstructing the RF signal output from the power amplifier 3001, the decision matrix is ​​used using equation (6) presented below The matrix maps the twelve (12) measured I and Q sample values ​​to the real and imaginary parts of the DFT of the RF signal output from power amplifier 3001.

[0141] In equation (6), A n is the complex Fourier coefficient of the nth harmonic.

[0142] matrix The elements of can be obtained by applying equations (3a) and (3b) for each phase value. Therefore, the matrix can be obtained from the following equations (7a) and (7b): Elements: where index k has values ​​1, 3, 5, 7, 9, and 11, and where m is a phase index with values ​​0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11. Thus, the full matrix equation (6) can be rewritten as presented in equation (8) below:

[0143] In many embodiments, the matrix may be pre-computed And it is hard-coded into the board module controller (BMC) 3019, because the matrix depends only on the selected phase and harmonic order.

[0144] Once the Fourier component A is obtained n , these components can be used to reconstruct the waveform according to the following equation (9):

[0145] FIG. 22A to FIG. 22C An example is shown of reconstructing the RF signal output from power amplifier 3001 at three different frequencies by the power guarantee circuit by reducing the contribution of the higher harmonics described herein. Fig.22A The reconstruction of the RF signal at a frequency of 1.0 MHz is shown. Fig. 22B Shown is the reconstruction of the RF signal at a frequency of 2.0 MHz. Fig. 22C Shows the reconstruction of the RF signal at a frequency of 3.0 MHz. Fig.22A , waveform 22001a is the waveform reconstructed using equation (9), and waveform 22003a is the output of the differential oscilloscope probe measuring the signal input to the demodulator. Fig. 22B , waveform 22001b is the waveform reconstructed using equation (9), and waveform 22003b is the output of the differential oscilloscope probe measuring the signal input to the demodulator. Fig. 22C , waveform 22001c is the waveform reconstructed using equation (9), and waveform 22003c is the output of the differential oscilloscope probe measuring the signal input to the demodulator. FIG. 22A to FIG. 22C Note that the reconstructed waveform closely matches the measured waveform.

[0146] The above-described embodiments of the multi-phase shifting method used by the power guarantee circuit to reconstruct the RF signal output from the power amplifier 3001 can reduce the requirements for the operating frequency required by the LO clock. In conventional methods, the operating frequency of the LO clock using conventional methods will operate at a frequency corresponding to a second, third, fourth, fifth, sixth, or other higher harmonic frequency. In such conventional methods, the clock frequency of the demodulator is then set to about four (4) times the harmonic frequency of the frequency at which the LO clock operates. This setting can increase circuit complexity, noise, and / or cost. The multi-phase shifting method described herein can be applied to higher harmonic frequencies without increasing the operating frequency of the LO clock frequency and / or without making any other changes to the electronic hardware. Correction of errors in measurement results obtained from power measurement systems

[0147] In various embodiments, the RF power delivered to the ultrasonic transducer 200 may be different from the RF power output from the power amplifier 3001 as measured by the power measurement system 3007. The difference between the RF power delivered to the ultrasonic transducer 200 and the RF output power measured by the power measurement system 3007 may be due to one or more of the following: (i) errors due to parasitic reactance on the circuit board of the RFTH module; (ii) errors due to parasitic reactance in the current and voltage sensing resistors used in the power measurement system 3007; (iii) deviations from nominal gain in the power measurement system 3007 and / or the IQ demodulator of the power amplifier 3001; (iv) insertion losses in the transformer used in the power measurement system 3007; (v) undesirable impedance transformation effects in the cable connecting the RFTH module and the ultrasonic transducer; and / or (vi) phase errors between voltage and current measurements in the IQ demodulator. Fig.23A Different sources of error that may cause a difference between the RF power delivered to the ultrasonic transducer 200 and the RF output power measured by the power measurement system 3007 are described. Fig.23A In FIG. 23001 , the deviation from the nominal gain in the IQ demodulator and amplifier is shown in block 23001, the error due to the parasitic reactance in the current sensing resistor and voltage sensing components and the PCB is shown in blocks 23003 and 23005, and the error due to undesirable cable effects is shown in block 23007. Different error sources can be caused by Fig. 23B It is modeled by the equivalent two-port network 23009 shown in FIG. 2 , which is arranged between the power amplifier 3001 and the ultrasonic transducer 200 .

[0148] To reduce the difference between the RF power delivered to the ultrasonic transducer 200 and the RF output power measured by the power measurement system 3007, the power measurement system 3007 may include a self-calibrating two-port network compensation module 24001, such as Fig.24As shown in , the self-calibrating two-port network compensation module captures the different sources of error described above, which results in the difference between the RF power delivered to the ultrasonic transducer 200 and the RF output power measured by the power measurement system 3007.

[0149] To correct various errors, the following method is used to obtain the two-port network parameters of the two-port network compensation module 24001. The RF signal is delivered to a set of N known load impedances Z within the impedance range. L,N , these impedances have magnitudes |Z| between 20Ω and 200Ω and phases ∠Z between -60° and 60°. N known load impedances are attached to port 2 of the two-port network, and the power measurement system 3007 is attached to port 1 of the two-port network. Each load Z is measured at port 2 L,N The voltage V 2,N (For example, using an oscilloscope), while at port 1 the voltage V is measured by the power measurement system 3007 1,N and current I 1,N For each of the N known loads, a least squares fit is performed to obtain the voltage V measured by the power measurement system at port 1 from 1,N and current I 1,N And each load Z L,N The voltage V 2,N And by V 2,N With Z L,N The ratio gives the corresponding current I 2,N A series of mathematical operations are performed to determine a set of estimated complex-valued two-port network parameters that minimize the difference between the measurement results obtained by the power measurement system 3007 and the measured voltage on the known impedance.

[0150] When the two-port network parameters are obtained using a set of N known loads spanning the expected operating impedance range, the resulting values ​​of the two-port network parameters can be stable and predict impedances that are not in the set of N impedances used to obtain the estimate. Since the two-port network parameters can be frequency dependent, the calculation is performed at each frequency to which the correction will be applied. If the measurements of voltage and impedance are densely sampled over frequency, linear interpolation of the two-port network parameters can be applied to obtain accurate estimates of the values ​​at frequencies between the sampled frequencies. For example, measuring at a number of frequencies between 32 and 256 across the operating frequency range of 1.0 MHz to 12.0 MHz can provide a smooth function suitable for accurate linear interpolation. In various embodiments, the RFTH module may include a calibration EEPROM integrated circuit (IC) that can store the two-port network parameters. The stored two-port network parameters can be used to correct the measurement results obtained by the power measurement system 3007 to reduce the difference between the RF power delivered to the ultrasonic transducer 200 and the RF output power measured by the power measurement system 3007. In various embodiments, the plurality (N) of calibrated impedances Z L Can be greater than or equal to 4. System and method for predicting output power delivered by an ultrasonic transducer

[0151] In various embodiments, it may be advantageous to predict how much acoustic power will be delivered before the amplifier is turned on. In systems where the power amplifier is not dedicated to a particular transducer, it may be difficult to predict how much acoustic power will be delivered before the amplifier is turned on. For example, in many embodiments of the therapy system, different power amplifiers may be used interchangeably with different transducers. Additionally, in many embodiments of the therapy system, it may be necessary to replace the transducer more frequently than the drive subsystem. In such embodiments, the power amplifier may be used to drive different transducers as they are replaced and / or upgraded.

[0152] Thus, some desired requirements for systems and methods for predicting output power may include (i) prediction of delivered electrical power with an error less than 0.3 dB; (ii) any transducer can be paired with any power amplifier and the power delivered by the transducer is within the error margin of the commanded power; and (iii) for a wide range of transducer impedances, the power delivered by the transducer is within the error margin of the commanded power.

[0153] In various systems and methods for predicting power, separate calibration measurements may be stored by the transducer and the power amplifier. Based on the calibration measurements stored in the power amplifier and the ultrasonic transducer, the RF power output by the power amplifier may be selected to output an RF signal at a desired output power that will deliver the desired acoustic energy when provided to the ultrasonic transducer. The present application covers two different prediction methods. The first method assumes that the variation in the output impedance of the power amplifier is small. The second method does not require this assumption, but requires a more complex calibration step. Example Method 1

[0154] In a first method, the ultrasonic transducer is configured to access a first lookup table (LUT) that stores a correspondence between the acoustic power output by the ultrasonic transducer and the electrical power delivered to a 50Ω load at the same amplitude setting. The first LUT may be generated during factory calibration of the ultrasonic transducer with a reference power amplifier. The first LUT may be stored in the ultrasonic transducer.

[0155] The power amplifier in the driver subsystem 3000 of the RFTH module can access a second LUT that stores the correspondence between the amplitude of the RF signal output from the power amplifier and the power of a 50Ω load obtained during factory calibration of the power amplifier. The second LUT can be stored in the power amplifier, the driver subsystem 3000, or the RFTH module. Example Method 2

[0156] In the second method, a first lookup table (LUT) including a correspondence between impedance and electro-acoustic conversion efficiency is generated during factory calibration of the ultrasonic transducer and can be stored in the ultrasonic transducer.

[0157] A second LUT is generated, which includes the power amplifier output impedance and the Thevenin equivalent source voltage that vary according to the amplitude setting. The second LUT can be stored in the power amplifier, the driver subsystem 3000 or the RFTH module.

[0158] The electronic processing system may be configured to calculate the electrical power of the transducer load impedance that will be needed to produce the desired acoustic power. The electronic processing system may be further configured to calculate an amplitude setting for a power amplifier that will output the electrical power that produces the desired acoustic power. Power calibration and assurance system

[0159] Transducers used for HIFU often exhibit a tolerance on their resonant frequency. For example, the tolerance on the resonant frequency for a large number of manufactured transducers may be + / 7%. The transducer resonant frequency may also change over transducer life and temperature. To ensure that the transducer is driven at its resonant frequency, the frequency of the drive signal may be swept over a frequency range containing the resonant frequency while measuring the power or impedance reflected by the transducer. The proximity to the center frequency may be determined by finding the frequency that reduces / minimizes the deviation of the impedance phase from zero, reduces / minimizes or increases / maximizes the impedance amplitude, reduces / minimizes the voltage standing wave ratio, reduces / minimizes the reflected power, or minimizes the reflection coefficient. In various embodiments, the range of the frequency sweep may be set to + / -100KHz around the nominal resonant frequency while monitoring the voltage standing wave ratio at each frequency and selecting the frequency with the lowest or smallest voltage standing wave ratio.

[0160] Because the transducer impedance observed at a fixed frequency can change as the resonant frequency changes due to, for example, aging and / or temperature, it is beneficial to be able to dynamically adjust the power to compensate for such changes. In some embodiments, a power guarantee measurement can be used to measure the electrical power delivered to the transducer, compare the electrical power to the desired electrical power, and adjust the driver amplitude or drive frequency in order to reduce the error between the measured power and the desired power.

[0161] In some embodiments, the power guarantee system may be used to measure the load impedance. A priori knowledge of the impedance of other system components located between the power guarantee system and the transducer may be used to transform the power guarantee measurement via a two-port network representing the system to determine the impedance observed to the transducer. In some embodiments, the transducer impedance obtained in this manner may be used to determine the electrical power required to achieve a desired acoustic power from the transducer. In some embodiments, the measurement of the transducer impedance obtained during therapy delivery may be used to adjust the drive amplitude in order to achieve the desired electrical power delivered to the transducer and thus the desired acoustic power output from the transducer.

[0162] The therapeutic efficacy of HIFU may depend on having an acoustically transparent coupling between the transducer and the treated tissue. Typically, this coupling can be achieved by using a gel placed between the transducer and the skin. However, improper placement of the transducer in the gel or in bubbles in the gel may result in poor coupling. Therefore, it is necessary to measure the quality of the coupling before initiating therapy delivery and monitor the coupling quality throughout the treatment. A characteristic of well-coupled tissue is that the interface between the tissue and the coupling medium will produce a small reflectivity of the ultrasonic energy. For example, a well-coupled ultrasonic transducer will reflect less than 5% of the incident power at the tissue-gel interface.

[0163] In some embodiments, the coupling quality is monitored during therapy delivery by monitoring the level of reflected ultrasonic energy. In order to provide axial resolution about the site of disruption in the coupling, the ultrasound used to observe the reflected energy may be pulsed rather than continuous in nature. The use of a pulsed waveform allows the distance from the transducer to the reflecting surface to be measured. In some embodiments, the therapy transducer may be used as a sensor in pulse-echo mode to detect the reflection of the coupling. In other embodiments, the therapy transducer may be used to excite the coupling material and the auxiliary transducer may be used to measure the reflected signal. In some embodiments, the reflection from a reference surface in the power delivery path may be used as an amplitude reference, and the reflection from the coupling surface is compared thereto to determine whether the coupling is acceptable. In some embodiments, the system may stop delivering therapy until the reflected power is below an acceptable threshold.

[0164] In some embodiments, the calibration power assurance system can be used to measure the impedance of the transducer. The measured impedance fits a model of the transducer impedance. In some embodiments, the model of the transducer impedance can be a circuit model, such as a Butterworth-van Dyke model. In some embodiments, the model of the transducer impedance can be a transmission line model, such as a Krimholtz, Leedom, and Matthaei (KLM) model. In some embodiments, the model of the transducer impedance can include clamping capacitance, coupling coefficient, and radiation resistance as parameters. In some embodiments, changes in the model parameters can indicate changes in the transducer characteristics due to aging. Therefore, changes in the model parameters can be used to track the aging or temperature of the transducer over time. In some embodiments, the model parameters can be used as acceptability criteria. In some embodiments, changes in the model parameters can be used to estimate the drive power required to obtain the desired acoustic power. Additional systematic reviews

[0165] In some embodiments, the control panel 300 includes a communication system (e.g., wifi, bluetooth, modem, etc. to communicate with another party, manufacturer, supplier, service provider, the Internet and / or the cloud. In some embodiments, the cart 301 has a power supply, such as a power connection to a battery and / or one or more wires for connecting power, communication (e.g., Ethernet) to the system 20. In some embodiments, the system 20 includes the cart 301. In some embodiments, the system 20 does not include the cart 301. The handle 100 can be coupled to the controller 300 via an interface 130, which can be a wired or wireless interface. The interface 130 can be coupled to the handle 100 via a connector 145. The distal end of the interface 130 can be connected to a controller connector on a circuit 345 (not shown). In one embodiment, the interface 130 can transmit controllable power from the controller 300 to the handle 100. In one embodiment, the system 20 has ultra-high definition (high definition) for subcutaneous structures. definition; HD) visualization to improve imaging. In one embodiment, the system has more than 20 therapy channels (e.g., 8 channels) and precision linear drive motors that double the accuracy of treatment while increasing speed (e.g., by 25%, 40%, 50%, 60%, 75%, 100%, or more than 100%). Together, these features establish one of the most versatile system platforms in the industry and provide the foundation for unprecedented future possibilities.

[0166] The controller 300 may include connectivity to one or more interactive graphical displays 310, which may include a touch screen monitor and a graphical user interface (GUI), which allows the user to interact with the ultrasound system 20. In one embodiment, a second smaller, more mobile display allows the user to more easily locate and view the treatment screen. In one embodiment, the second display allows the system user to view the treatment screen (e.g., on a wall, on a mobile device, on a large screen, on a remote screen). In one embodiment, the graphical display 310 includes a touch screen interface 315 (not shown). In various embodiments, the display 310 sets and displays operating conditions, including device startup status, treatment parameters, system messages and prompts, and ultrasound images. In various embodiments, the controller 300 may be adapted and / or configured to include, for example, a microprocessor with software and input / output devices, systems and devices for controlling electronic and / or mechanical scanning and / or multitasking of transducers and / or multitasking of transducer modules, systems for power delivery, systems for monitoring, systems for sensing spatial position of probes and / or transducers and / or multitasking of transducer modules, and / or systems for handling user inputs and recording treatment effects, among other systems.

[0167] In one embodiment, the handle 100 includes one or more finger-activated controls or switches, such as 150 and 160. In various embodiments, one or more thermal treatment controls 160 (e.g., switches, buttons) start and / or stop treatment. In various embodiments, one or more imaging controls 150 (e.g., switches, buttons) start and / or stop imaging. In one embodiment, the handle 100 may include a removable module 200. In other embodiments, the module 200 may be non-removable. In various embodiments, the module 200 may be mechanically coupled to the handle 100 using a latch or coupler 140. In various embodiments, an interface guide 235 or multiple interface guides 235 may be used to assist in coupling the module 200 to the handle 100. The module 200 may include one or more ultrasonic transducers 280. In some embodiments, the ultrasonic transducer 280 includes one or more ultrasonic components. The module 200 may include one or more ultrasonic components. The handle 100 may include an imaging module only, a treatment module only, an imaging and treatment module, and the like. In various embodiments, the ultrasonic transducer 280 may be movable in one or more directions 290 within the module 200. The transducer 280 is connected to a motion mechanism 400. In various embodiments, the motion mechanism includes zero, one or more bearings, shafts, rods, screws, lead screws 401, encoders 402 (e.g., optical encoders for measuring the position of the transducer 280), motors 403 (e.g., stepper motors) to help ensure accurate and repeatable movement of the transducer 280 within the module 200. In various embodiments, the module 200 may include a transducer 280 that can transmit energy via a sound-permeable member 230. In one embodiment, the control module 300 may be coupled to the handle 100 via the interface 130, and the graphical user interface 310 may be adapted and / or configured for use in the control module 200. In one embodiment, the control module 300 may provide power to the handle 100. In one embodiment, the handle 100 may include a power source. In one embodiment, the switch 150 may be adapted and / or configured to control a tissue imaging function, and the switch 160 may be adapted and / or configured to control a tissue treatment function. In various embodiments, the module 200 controls the transducer 280 via the control system 300 to provide the emitted energy 50 with a suitable focus depth, distribution, timing, and energy level to achieve the desired treatment effect through the thermal coagulation zone 550.

[0168] In one embodiment, module 200 may be coupled to handle 100. Module 200 may transmit and receive energy, such as ultrasonic energy. Module 200 may be electronically coupled to handle 100, and this coupling may include an interface for communicating with controller 300. In one embodiment, interface guide 235 may be adapted and / or configured to provide electronic communication between module 200 and handle 100. Module 200 may include various probe and / or transducer configurations. For example, module 200 may be adapted and / or configured for combined dual-mode imaging / therapy transducers, coupled or co-housed imaging / therapy transducers, separate therapy and imaging probes, and the like. In one embodiment, when module 200 is inserted into or connected to handle 100, controller 300 automatically detects it and updates interactive graphical display 310.

[0169] In some embodiments, an access key 320 (e.g., a secure USB drive key) is removably connected to the system 20 to allow the system 20 to function. In various embodiments, the access key is programmed to be consumer-specific and serves multiple functions, including system security, country-specific treatment guidelines and functional access, software upgrades, support log transfer and / or credit transfer and / or storage. In various embodiments, the system 20 has Internet and / or data connectivity. In one embodiment, connectivity provides a method for transferring data between the system 20 provider and the consumer. In various embodiments, the data includes credit, software updates, and support logs. Connectivity is divided into different model embodiments based on how the user console is connected to the Internet. In one embodiment, disconnected model connectivity includes a console disconnected from the Internet, and the consumer cannot access the Internet. Credit transfer and software upgrades are performed by shipping an access key (e.g., a USB drive) to the consumer. In one embodiment, semi-connected model connectivity includes a console disconnected from the Internet, but the consumer can access the Internet. Credit transfers, software upgrades, and support log transfers are performed using the consumer's personal computer, smartphone, or other computing device in conjunction with a system access key to transfer data. In one embodiment, full connectivity model connectivity includes a console that connects wirelessly to the internet using wifi, cellular modem, Bluetooth, or other protocols. Credit transfers, software upgrades, and support log transfers are performed directly between the control panel and the cloud. In various embodiments, the system 20 is connected to an online portal for streamlined inventory management, on-demand treatment purchases, and business analytics insights to drive consumer aesthetic treatment business to the next level.

[0170] Figure 2Schematic illustration of an ultrasound system 20 coupled to an area of ​​interest 10. In various embodiments, tissues below or even at the surface of the skin, such as the epidermis, dermis, hypodermis, fascia, and superficial muscular aponeurosis system ("SMAS") and / or muscles, are non-invasively treated with ultrasound energy. The tissue may also include blood vessels and / or nerves. The ultrasound energy may be focused, unfocused, or defocused, and applied to an area of ​​interest containing at least one of the epidermis, dermis, hypodermis, fascia, and SMAS to achieve a therapeutic effect. In various embodiments, the tissue layer of the area of ​​interest 10 may be at any part of the body of an individual. In one embodiment, the tissue layer is in the head and facial region of an individual. A cross-sectional portion of the tissue of the area of ​​interest 10 includes a skin surface 501, an epidermis layer 502, a dermis layer 503, a fat layer 505, a superficial muscular aponeurosis system 507 (hereinafter "SMAS507"), and a muscle layer 509. The tissue may also include hypodermis 504, which may include any tissue below the dermis layer 503. The combination of these layers may be generally referred to as subcutaneous tissue 510. Figure 2 Also illustrated in the figure is a treatment area 525 below the surface 501. In one embodiment, the surface 501 may be the skin surface of the individual 500. Although embodiments related to therapies at tissue layers may be used as examples herein, the system may be applied to any tissue within the body. In various embodiments, the system and / or method may be used on tissue (including but not limited to muscle, fascia, SMAS, dermis, epidermis, fat, adipocytes, cellulite, which may be referred to as female lipodystrophy (e.g., non-dimple female lipodystrophy), collagen, skin, blood vessels) on the face, neck, head, arms, legs, or any other part of the body (including body cavities). In various embodiments, a reduction in cellulite (e.g., non-dimple female lipodystrophy) is achieved by 2%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, 75%, 80%, 90%, 95% and any range thereof.

[0171] See also Figure 2 As described in the description, an embodiment of the ultrasound system 20 includes a handle 100, a module 200, and a controller 300. In one embodiment, the module 200 includes a transducer 280. The transducer 280 of various embodiments of the ultrasound system 20 can be adapted and / or configured to treat tissue at a focal depth, which is the distance between the transducer 280 and the target tissue to be treated. In various embodiments, for a given transducer 280, the focal depth can be fixed. In one embodiment, for a given transducer 280, the focal depth is variable. In one embodiment, the transducer 280 is configured to treat at multiple depths (e.g., 1.5 mm, 3.0 mm, 4.5 mm, or other depths) below the skin surface simultaneously.

[0172] As discussed above, the module 200 may include a transducer that can transmit energy via the acoustically permeable member 230. In one embodiment, the transducer 280 may have an offset distance, which is the distance between the transducer 280 and the surface of the acoustically permeable member 230. In one embodiment, the focal depth of the transducer 280 is a fixed distance from the transducer. In one embodiment, the transducer 280 may have a fixed offset distance from the transducer to the acoustically permeable member 230. In one embodiment, the acoustically permeable member 230 is adapted and / or configured at a location on the module 200 or ultrasound system 20 for contacting the skin surface 501. In various embodiments, the focal depth exceeds the offset distance by a certain amount to correspond to treatment at a target area at a tissue depth below the skin surface 501. In various embodiments, when the ultrasound system 20 is placed in physical contact with the skin surface 501, the tissue depth is the distance between the acoustically permeable member 230 and the target area, measured as the distance from the portion of the handle 100 or module 200 surface that contacts the skin (with or without acoustic coupling gel, medium, etc.) and the tissue depth from the skin surface contact point to the target area. In one embodiment, the focus depth may correspond to the sum of the offset distance (e.g., measured as the distance to the surface of the acoustically permeable member 230 that contacts the coupling medium and / or skin 501) plus the tissue depth from below the skin surface 501 to the target area. In various embodiments, the acoustically permeable member 230 is not used.

[0173] The coupling assembly may include various substances, materials and / or devices to facilitate the coupling of the transducer 280 or module 200 to the region of interest. For example, the coupling assembly may include an acoustic coupling system adapted and / or configured for acoustic coupling of ultrasonic energy and signals. An acoustic coupling system with possible connectors such as a manifold can be used to couple sound into the region of interest, providing liquid or fluid-filled lens focusing. The coupling system may facilitate this coupling by using one or more coupling media, which include air, gas, water, liquid, fluid, gel, solid, non-gel and / or any combination thereof, or any other medium that allows the transmission of signals between the transducer 280 and the region of interest. In one embodiment, one or more coupling media are provided inside the transducer. In one embodiment, the fluid-filled module 200 contains one or more coupling media inside the housing. In one embodiment, the fluid-filled module 200 contains one or more coupling media inside a sealed housing that can be separated from the dry portion of the ultrasonic device. In various embodiments, the coupling medium is used to transmit ultrasonic energy between one or more devices and tissue with a transmission efficiency of 100%, 99% or greater, 98% or greater, 95% or greater, 90% or greater, 80% or greater, 75% or greater, 60% or greater, 50% or greater, 40% or greater, 30% or greater, 25% or greater, 20% or greater, 10% or greater, and / or 5% or greater.

[0174] In various embodiments, the transducer 280 can image and treat the area of ​​interest at any suitable tissue depth. In one embodiment, the transducer module 280 can provide acoustic power in the range of about 1 W or less, between about 1 W and about 100 W, and greater than about 100 W (e.g., 200 W, 300 W, 400 W, 500 W). In one embodiment, the transducer module 280 can provide acoustic power at a frequency of about 1 MHz or less, between about 1 MHz and about 10 MHz (e.g., 3 MHz, 4 MHz, 4.5 MHz, 7 MHz, 10 MHz), and greater than about 10 MHz. In one embodiment, the module 200 has a focal depth for treating at a tissue depth of about 4.5 mm below the skin surface 501. In one embodiment, the module 200 has a focal depth for treating at a tissue depth of about 3 mm below the skin surface 501. In one embodiment, the module 200 has a focal depth for treating at a tissue depth of about 1.5 mm below the skin surface 501. Some non-limiting embodiments of the transducer 280 or module 200 may be adapted and / or configured for delivering ultrasound energy at the following tissue depths: 1.5 mm, 3 mm, 4.5 mm, 6 mm, 7 mm, less than 3 mm, between 3 mm and 4.5 mm, between 4.5 mm and 6 mm, greater than greater than 4.5 mm, greater than 6 mm, etc., and any value within the range of 0 to 3 mm, 0 to 4.5 mm, 0 to 6 mm, 0 to 25 mm, 0 to 100 mm, etc., and any depth therein. In one embodiment, the ultrasound system 20 has two or more transducer modules 280. For example, a first transducer module may apply treatment at a first tissue depth (e.g., about 4.5 mm), a second transducer module may apply treatment at a second tissue depth (e.g., about 3 mm), and a third transducer module may apply treatment at a third tissue depth (e.g., about 1.5 to 2 mm). In one embodiment, at least some or all of the transducer modules may be adapted and / or configured to apply treatment at substantially the same depth.

[0175] In various embodiments, changing the number of focal sites (e.g., such as with tissue depth) of the ultrasound program may be advantageous because it allows the patient to be treated at different tissue depths even if the focal depth of the transducer 280 is fixed. This can provide a synergistic effect and maximize the clinical results of a single treatment course. For example, treatment at multiple depths below a single surface area allows a larger total volume of tissue to be treated, which results in enhanced collagen formation and tightening. In addition, treatment at different depths affects different types of tissue, thereby producing different clinical effects, which together provide an enhanced overall cosmetic effect. For example, superficial treatment can reduce the visibility of wrinkles, while deep treatment can lead to the formation of more collagen growth. Likewise, treatment at various sites at the same or different depths can improve treatment.

[0176] Although in some embodiments, it may be advantageous to treat an individual at different locations in one treatment course, in other embodiments, sequential treatment over time may be beneficial. For example, an individual may be treated at a depth below the same surface area at a first time, at a second depth at a second time, and so on. In various embodiments, the time may be on the order of nanoseconds, microseconds, milliseconds, seconds, minutes, hours, days, weeks, months, or other time periods. The new collagen produced by the first treatment may be more sensitive to subsequent treatments, which may be required for some indications. Alternatively, in a single treatment course, multi-depth treatments below the same surface area may be advantageous, but because treatment at one depth may synergistically enhance or supplement treatment at another depth (due to, for example, enhanced blood flow, stimulation of growth factors, hormone stimulation, etc.). In several embodiments, different transducer modules provide treatment at different depths. In one embodiment, a single transducer module may be adjusted or controlled for different depths. A safety feature that minimizes the risk of selecting an incorrect depth may be used in conjunction with a single module system.

[0177] In some embodiments, a method of treating the lower face and neck area (e.g., the submental area) is provided. In some embodiments, a method of treating (e.g., softening) the mentolabial fold is provided. In other embodiments, a method of treating the eye area (e.g., eyelid bags, treating infraorbital laxity) is provided. With some embodiments, improvement in upper eyelid laxity and improvement in periorbital lines and texture will be achieved by treating at variable depths. By treating at different locations in a single treatment session, the best clinical effect (e.g., softening, tightening) can be achieved. In some embodiments, the treatment methods described herein are non-invasive cosmetic procedures. In some embodiments, the methods may be used in conjunction with invasive procedures such as surgical face lifts or liposuction, where skin tightening is desired. In various embodiments, the methods may be applied to any part of the body.

[0178] In one embodiment, the transducer module 200 permits a treatment sequence at a fixed depth at or below the skin surface. In one embodiment, the transducer module permits a treatment sequence at one, two, or more than two variable or fixed depths below the dermis. In several embodiments, the transducer module includes a moving mechanism that is adapted and / or configured to guide ultrasound treatment of a series of individual thermal injuries (hereinafter "thermal coagulation points" or "TCPs") at a fixed focal depth. In one embodiment, the sequence of individual TCPs has a treatment spacing in the range of about 0.01 mm to about 25 mm (e.g., 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 5 mm, 10 mm, 20 mm, and any range of values ​​therein), wherein the jitter variation of the spacing is 1 to 50% (e.g., 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, and any range thereof). For example, the spacing may be 1.1 mm or less, 1.5 mm or greater, between about 1.1 mm and about 1.5 mm, and so on. In one embodiment, individual TCPs are discrete. In one embodiment, individual TCPs are overlapping. In one specific example, the moving mechanism is adapted and / or configured to be programmed to provide a variable spacing between individual TCPs. In one embodiment, the jitter may be adapted and / or configured to provide a variable spacing between individual (or single) TCPs. In several embodiments, the transducer module includes a moving mechanism that is adapted and / or configured to guide the ultrasound treatment in a sequence so that the TCPs are formed into a linear or substantially linear sequence separated by a treatment distance. For example, the transducer module may be adapted and / or configured to form TCPs along a first linear sequence and a second linear sequence separated by a treatment distance from the first linear sequence. In one embodiment, the treatment distance between adjacent linear sequences of individual TCPs is in the range of about 0.01 mm to about 25 mm. In one embodiment, the treatment distance between adjacent linear sequences of individual TCPs is in the range of about 0.01 mm to about 50 mm. For example, the treatment distance may be 2 mm or less, 3 mm or greater, between about 2 mm and about 3 mm, and so on. In several embodiments, the transducer module may include one or more moving mechanisms 400 adapted and / or configured to guide the ultrasound treatment in a sequence so that the TCPs are formed into linear or substantially linear individual thermal injury sequences separated from other linear sequences by the treatment distance. In one embodiment, the treatment is applied in a first direction 290 (e.g., push). In one embodiment, the treatment is applied in a direction opposite to the first direction 290 (e.g., pull). In one embodiment, the treatment is applied in both the first direction 290 and the direction opposite to the first direction (e.g., push and pull).In one embodiment, the therapeutic distance separating the linear or substantially linear TCP sequences is the same or substantially the same. In one embodiment, the therapeutic distance separating the linear or substantially linear TCP sequences is different or substantially different for various adjacent pairs of linear TCP sequences.

[0179] In one embodiment, a first and second extractable transducer module is provided. In one embodiment, each of the first and second transducer modules is adapted and / or configured for both ultrasound imaging and ultrasound therapy. In one embodiment, the transducer module is adapted and / or configured for therapy only. In one embodiment, the imaging transducer can be attached to the handle, or handle, of the probe. The first and second transducer modules are adapted and / or configured for interchangeable coupling to the handle. The first transducer module is adapted and / or configured to apply ultrasound therapy to a first tissue layer, and the second transducer module is adapted and / or configured to apply ultrasound therapy to a second tissue layer. The second tissue layer is at a depth different from the first tissue layer.

[0180] In various embodiments, the emitted energy is provided to be delivered with appropriate focus depth, distribution, timing and energy level by the module 200 through the control operation of the control system 300 to achieve the desired therapeutic effect of controlled thermal injury to treat at least one of the epidermis layer 502, the dermis layer 503, the fat layer 505, the SMAS layer 507, the muscle layer 509 and / or the hypodermis 504. In various embodiments, the emitted energy can be focused at a depth corresponding to the depth used to treat muscle. In various embodiments, the depth can correspond to any tissue, tissue layer, skin, epidermis, dermis, hypodermis, fat, SMAS, muscle, blood vessel, nerve or other tissue. During operation, the module 200 and / or transducer 280 can also be mechanically and / or electronically scanned along the surface 501 to treat an extended area. Before, during and after delivering ultrasonic energy 50 to at least one of the epidermis 502, dermis 503, hypodermis 504, fat layer 505, SMAS layer 507 and / or muscle layer 509, monitoring of the treatment area and surrounding structures can be provided to plan and evaluate the results and / or provide feedback to the controller 300 and the user via the graphical interface 310.

[0181] In one embodiment, the ultrasonic system 20 generates ultrasonic energy directed to a surface 501 and focused below the surface. The controlled and focused ultrasonic energy 50 generates thermal coagulation points or zones (TCPs) 550. In one embodiment, the ultrasonic energy 50 generates voids in the subcutaneous tissue 510. In various embodiments, the target of the transmitted energy 50 is the tissue below the surface 501, and the energy cuts, ablates, coagulates, micro-ablates, manipulates and / or generates TCPs 550 in the tissue portion 10 at a specified focal depth below the surface 501. In one embodiment, during a treatment sequence, the transducer 280 may move in a direction indicated by arrows labeled 290 at specified intervals to generate a series of treatment zones, each of which receives the transmitted energy 50 to generate one or more TCPs 550. In one embodiment, the TCPs may be spaced orthogonal to the direction of motion of the transducer 280. In some embodiments, the orientation of the spaced TCPs may be set to any angle from 0 to 180 degrees to the arrow 290. In some embodiments, the orientation of the spaced TCPs may be set to any angle between 0 and 180 degrees based on the orientation of the polarization regions on the transducer 280 .

[0182] In various embodiments, the transducer module may include one or more transducer components. The transducer components may include piezoelectrically active materials, such as lead zirconante titanate (PZT), or any other piezoelectrically active materials, such as piezoelectric ceramics, crystals, plastics, and / or composites, as well as lithium niobate, lead titanate, barium titanate, and / or lead metaniobate. In various embodiments, in addition to or in lieu of piezoelectrically active materials, the transducer module may include any other material adapted and / or configured for generating radiation and / or acoustic energy. In various embodiments, the transducer module may be adapted and / or configured to operate at different frequencies and treatment depths. Transducer properties may be determined by the outer diameter ("OD") and focal length (F). L ) definition. In one embodiment, the transducer may be adapted and / or configured to have OD = 19 mm and F L =15mm. In other embodiments, other suitable OD and F may be used. L Values, such as OD less than about 19 mm, greater than about 19 mm, etc. and F less than about 15 mm, greater than about 15 mm, etc. L. The transducer module may be adapted and / or configured to apply ultrasonic energy at different target tissue depths. As described above, in some embodiments, the transducer module includes moving mechanisms that are adapted and / or configured to guide ultrasonic treatment in a linear or substantially linear sequence of individual TCPs, wherein there is a treatment spacing between individual TCPs. For example, the treatment spacing may be about 1.1 mm, 1.5 mm, etc. In some embodiments, the transducer module may further include moving mechanisms that are adapted and / or configured to guide ultrasonic treatment in a sequence so that the TCPs are formed as a linear or substantially linear sequence separated by a treatment distance. For example, the transducer module may be adapted and / or configured to form TCPs along a first linear sequence and a second linear sequence separated from the first linear sequence by a treatment distance between about 2 mm and 3 mm. In one embodiment, the user can manually move the transducer module on the surface of the treatment area so that an adjacent linear sequence of TCPs is produced. In one embodiment, the movement mechanism can automatically move the transducer modules over the surface of the treatment area such that a contiguous linear sequence of TCPs is produced.

[0183] Various embodiments relate to devices or methods for controlling the delivery of energy to a target area, such as tissue. In various embodiments, the various forms of energy may include acoustic, ultrasonic, light, laser, radio frequency (RF), microwave, electromagnetic, radiation, heat, cryogenic, electron beam, photon-based, magnetic, magnetic resonance, and / or other forms of energy. Various embodiments relate to devices or methods for splitting an ultrasonic energy beam into multiple beams. In various embodiments, the device or method may be used to modify the delivery of ultrasonic acoustic energy in any procedure such as, but not limited to, therapeutic ultrasound, diagnostic ultrasound, ultrasonic welding, any application involving coupling mechanical waves to an object, and other procedures. Generally speaking, in the case of therapeutic ultrasound, tissue effects are achieved by focusing the acoustic energy from a pore using focusing techniques. In some cases, high intensity focused ultrasound (HIFU) is used in this manner for therapeutic purposes. In one embodiment, the tissue effect produced by applying therapeutic ultrasound at a specific depth may be referred to as the generation of a thermal coagulation point (TCP). In some embodiments, the area may include a point. In some embodiments, the zone is a line, plane, sphere, ellipse, cube or other one, two or three dimensional shape. It is through the generation of TCP at specific locations where thermal and / or mechanical ablation of tissue can occur non-invasively or remotely. In some embodiments, ultrasound treatment does not include cavitation and / or shock waves. In some embodiments, ultrasound treatment includes cavitation and / or shock waves.

[0184] In one embodiment, TCP can be generated in a linear or substantially linear, curved or substantially curved area or sequence, wherein each individual TCP is separated from an adjacent TCP by a treatment spacing. In one embodiment, multiple sequences of TCP can be generated in the treatment area. For example, TCP can be formed along a first sequence and a second sequence separated from the first sequence by a treatment distance. Although the treatment of therapeutic ultrasound can be implemented by generating individual TCPs with one and multiple sequences of individual TCPs, it may be necessary to reduce the treatment time and reduce the corresponding risk of pain and / or discomfort suffered by the patient. Therapy time can be reduced by forming multiple TCPs simultaneously, almost simultaneously or sequentially. In some embodiments, by generating multiple TCPs, the treatment time can be reduced by 10%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or more than 80%.

[0185] For example, in some non-limiting embodiments, the power system for the transducer can be configured to focus at the following tissue depths: 0.5mm, 1.0mm, 1.5mm, 2mm, 3mm, 4.5mm, 6mm, less than 3mm, between 0.5mm and 5mm, between 1.5mm and 4.5mm, greater than greater than 4.5mm, greater than 6mm, and any value in the range of 0.1mm to 3mm, 0.1mm to 4.5mm, 0.1mm to 25mm, 0.1mm to 100mm, and any depth therein (e.g., 6mm, 10mm, 13mm, 15mm). In several embodiments, treatment is performed at a depth below the skin surface, and the skin surface is not damaged. In fact, the treatment effect achieved at a depth below the skin surface results in a good cosmetic appearance of the skin surface. In other embodiments, the skin surface is treated with ultrasound (e.g., at a depth of less than 0.5mm).

[0186] One benefit of the motion mechanism is that it can provide a more efficient, accurate and precise use of the ultrasonic transducer for imaging and / or therapy purposes. Compared to the traditional fixed array of multiple transducers fixed in the space in the housing, an advantage of this type of motion mechanism is that the fixed array is separated by a fixed distance. In one embodiment, the transducer module is configured to provide an acoustic power of ultrasonic therapy in the range of about 1W to about 100W (e.g., 3 to 30W, 7 to 30W, 21 to 33W) and a frequency of about 1MHz to about 10MHz, thereby heating the tissue to cause coagulation. In one embodiment, the transducer module is configured to provide an acoustic power of ultrasonic therapy in the range of about 1W to about 500W (e.g., 3 to 30W, 7 to 30W, 21 to 33W, 100W, 220W or greater than 220W) and a frequency of about 1MHz to about 12MHz, thereby heating the tissue to cause coagulation. In some embodiments, instantaneous energy is delivered. In some embodiments, average energy is delivered. In one embodiment, the acoustic power may range from 1 W to about 100 W in a frequency range of about 1 MHz to about 12 MHz (e.g., 1 MHz, 3 MHz, 4 MHz, 4.5 MHz, 7 MHz, 10 MHz, 2 to 12 MHz), or from about 10 W to about 50 W in a frequency range of about 3 MHz to about 8 MHz (e.g., 3 MHz, 4 MHz, 4.5 MHz, 7 MHz). In one embodiment, the acoustic power may range from 1 W to about 500 W in a frequency range of about 1 MHz to about 12 MHz (e.g., 1 MHz, 4 MHz, 7 MHz, 10 MHz, 2 to 12 MHz), or from about 10 W to about 220 W in a frequency range of about 3 MHz to about 8 MHz or 3 MHz to 10 MHz. In one embodiment, the acoustic power and frequency are about 40 W at about 4.3 MHz, and about 30 W at about 7.5 MHz (e.g., 7.0 MHz, 7.2 MHz, 7.4 MHz, 7.6 MHz, 7.8 MHz, 8.0 MHz). The acoustic energy generated by this acoustic power may be between about 0.01 joules ("J") to about 10 J (e.g., 0.25 J, 0.45 J, 0.5 J, 1.0 J, 1.05 J, 1.20 J, 1.25 J, 1.50 J, 4 J, 6 J, 8 J, 9 J) or between about 2 J to about 5 J. The acoustic energy generated by this acoustic power may be between about 0.01 J to about 60,000 J (e.g., via overall heating, targeting body contouring, submental fat, abdomen and / or flanks, arms, inner thighs, outer thighs, buttocks, loose abdomen, cellulite), about 10 J or between about 2 J to about 5 J. In one embodiment, the acoustic energy is in the range of less than about 3 J (e.g., 0.25 J, 0.45 J, 0.5 J, 1.0 J, 1.5 J, 1.20 J, 1.25 J, 1.50 J, 2.0 J, 2.5 J).In various embodiments, the treatment power intensity is 10 kW / cm. 2 Up to 100kW / cm 2 , 15kW / cm 2 Up to 70kW / cm 2 , 10kW / cm 2 Up to 15kW / cm 2 , 15kW / cm 2 Up to 20kW / cm 2 、17kW / cm 2 Up to 40kW / cm 2 , 15kW / cm 2 Up to 50kW / cm 2 , 20kW / cm 2 Up to 40kW / cm 2 , 15kW / cm 2 Up to 35kW / cm 2 , 15kW / cm 2 Up to 25kW / cm 2 , 25kW / cm 2 Up to 70kW / cm 2 and / or 40kW / cm 2 Up to 80kW / cm 2 .

[0187] In some embodiments described herein, the procedure is entirely cosmetic rather than medical. For example, in one embodiment, the method described herein need not be performed by a doctor, but rather is performed at a spa or other aesthetic institution. In some embodiments, a system can be used for non-invasive cosmetic treatment of the skin. In some embodiments, systems and methods are provided for performing various treatment and / or imaging procedures using directed and precise ultrasound waves by utilizing a thermal path of a single ultrasound therapy beam or by splitting the ultrasound therapy beam into two, three, four, or more than four simultaneous focal zones. In some embodiments, ultrasound waves are used for diagnostic and / or therapeutic purposes in the medical field, including but not limited to dermatology.

[0188] In various embodiments, ultrasound imaging is used to ensure adequate acoustic coupling during the delivery of ultrasound therapy treatment. In various embodiments, ultrasound imaging is used to prevent treatment at undesirable areas in the body such as bones or implants. Sound, unlike light, requires a medium for propagation. In one embodiment, the ultrasound therapy system uses gel to acoustically couple ultrasound energy from the transducer to the body via an acoustic window. In this embodiment, the gel is a medium that simulates the acoustic impedance properties of tissue, so that energy is efficiently transferred from the device to the tissue. Unfortunately, in some cases, any air pockets between the transducer and the tissue prevent proper coupling, and may therefore result in insufficient transfer of ultrasound therapy energy. Ultrasound imaging checks this coupling. Inadequate coupling may appear as shadows or vertical stripes in the ultrasound image, or a completely dark image. Even if there is sufficient coupling, tissues or objects such as bones or implants may also cause challenges, because these objects may have different acoustic impedance and absorption characteristics from soft tissues (e.g., skin, muscle). Therefore, objects between the device and the intended therapy focus, such as bones or implants, can cause significant reflections and heating at depths shallower than expected. Objects slightly beyond the focus (e.g., bones, etc.) can also cause problems because they reflect and easily absorb ultrasound from soft tissue. The reflected energy may inadvertently add to the energy already generated at the therapy focus, causing the temperature to rise higher than expected. Energy absorbed at the bone can cause heating of the bone or bone discomfort.

[0189] In various embodiments, the present invention improves safety features, improves efficacy, provides components for the safety and efficacy of whole body heating devices (such as band therapy, linear focused treatment zones, cylindrical focal lines, planes and / or volumes, etc.), for body contouring, submental fat, abdomen and / or flanks, arms, inner thighs, outer thighs, buttocks, laxity, abdominal laxity, etc., provides qualitative and / or quantitative assessment of coupling, provides fusion of high resolution images with coupled images for assessment of out-of-plane obstructions behind the lesion (e.g., bone, intestine, implants), and / or can be used to reduce the need for equal skills of ultrasound physicians.

[0190] In several embodiments disclosed herein, the non-invasive ultrasound system is adapted for use in achieving one or more of the following beneficial aesthetic and / or cosmetic improvements: face lift, brow lift, jowl lift, eye treatment (e.g., eyelid bags, treatment of infraorbital laxity), wrinkle reduction, fat reduction (e.g., treatment of fat and / or cellulite), treatment of cellulite (which may be referred to as female lipodystrophy) (e.g., dimple or non-dimple female lipodystrophy), décolletage improvement (e.g., upper chest), buttocks lift (e.g., buttocks tightening), skin tightening (e.g., treatment of laxity to tighten the face or body such as the face, neck, chest, arms, thighs, abdomen, buttocks, etc.), scar reduction, burn treatment, tattoo removal, vein removal, vein reduction, sweat gland treatment, hyperhidrosis treatment, sun spot removal, acne treatment, pimple reduction. In one embodiment, the thermocoagulation zone is directed to tissue beneath the skin, such as the superficial musculoaponeurotic system ("SMAS"), and another defocused energy is provided at the skin surface. In various embodiments, the ultrasound system is configured to focus ultrasound to produce local mechanical movement in tissues and cells to achieve the purpose of producing local heating for tissue coagulation, ablation and / or for mechanical cell membrane rupture. In various embodiments, the ultrasound system is configured to lift eyebrows (e.g., eyebrows). In various embodiments, the ultrasound system is configured to lift loose tissues, such as submental (under the chin) and neck tissue. In various embodiments, the ultrasound system is configured to improve chest lines and wrinkles. In various embodiments, the ultrasound system is configured to reduce fat. In various embodiments, the ultrasound system is configured to reduce the appearance of cellulite. In various embodiments, tissues below the surface of the skin or even at the surface of the skin, such as the epidermis, dermis, fascia, muscle, fat, and superficial aponeurosis system ("SMAS"), are treated non-invasively with ultrasound energy. Ultrasonic energy may be focused at one or more treatment points and / or zones, may be unfocused and / or defocused, and may be applied to an area of ​​interest containing at least one of the epidermis, dermis, hypodermis, fascia, muscle, fat, cellulite, and SMAS to achieve a cosmetic and / or therapeutic effect. In various embodiments, the system and / or method provides non-invasive dermatological treatment of tissue via thermal treatment, coagulation, ablation, and / or tightening. In one embodiment, fat reduction is achieved. In various embodiments, cellulite (e.g., dimples or non-dimple female lipodystrophy) is reduced or one or more characteristics (such as dimples, nodules, "orange peel" appearance, etc.) are improved by 10-20%, 20-40%, 40-60%, 60-80%, or greater than 80% (and overlapping ranges therein) compared to, for example, untreated tissue. In one embodiment, the cervical and chest areas are treated. In some embodiments, two, three, or more than three beneficial effects are achieved during the same treatment session and can be achieved simultaneously.

[0191] Various embodiments of the present invention address potential challenges presented by administering ultrasound therapy. In various embodiments, the time to form TCP at the target tissue to achieve the desired cosmetic and / or therapeutic treatment of the desired clinical method is reduced. In various embodiments, the target tissue is, but is not limited to, any of the following: skin, eyelids, eyelashes, eyebrows, caruncle, crow's feet, wrinkles, eyes, nose, mouth (e.g., nasolabial folds, perioral wrinkles), tongue, teeth, gums, ears, brain, heart, lungs, ribs, abdomen (e.g., for abdominal relaxation), stomach, liver, kidney, uterus, breast, vagina, prostate, testicles, glands, thyroid, viscera, hair, muscle, bone, ligament, cartilage, fat, fat labuli, adipose tissue, subcutaneous tissue, implanted tissue, implanted organ, lymph, tumor, cyst, abscess, or part of a nerve, or any combination thereof.

[0192] Various embodiments of ultrasound treatment and / or imaging devices are described in U.S. Application No. 12 / 996,616, published on May 12, 2011 as U.S. Publication No. 2011-0112405, which is the U.S. national phase of International Application No. PCT / US2009 / 046475, filed on June 5, 2009 and published in English on December 10, 2009, under 35 U.S.C. §371, which claims priority to U.S. Provisional Application No. 61 / 059,477, filed on June 6, 2008, each of which is incorporated herein by reference in its entirety. Various embodiments of ultrasound therapy and / or imaging devices are described in U.S. Application No. 14 / 193,234, published as U.S. Publication No. 2014 / 0257145 on September 11, 2014, which is incorporated herein by reference in its entirety. Various embodiments of ultrasound therapy and / or imaging devices are described in International Application PCT / US15 / 25581, published as WO 2015 / 160708 on October 22, 2015 as National Phase U.S. Application No. 15 / 302,436, published as U.S. Publication No. 2017 / 0028227 on February 2, 2017, each of which is incorporated herein by reference in its entirety. Various embodiments of ultrasound treatment and / or imaging devices are described in International Application PCT / US17 / 046703, which was published as WO 2018 / 035012 on February 22, 2018 as National Phase U.S. Application No. 15 / 562,384, each of which is incorporated herein by reference in its entirety.

[0193] Some embodiments and examples described herein are examples and are not intended to be limiting in describing the full scope of the devices, systems, and methods of such embodiments. Equivalent changes, modifications, and variations may be made to some embodiments, materials, compositions, and methods within the scope of the embodiments described herein with substantially similar results. Modifications, equivalents, and alternatives that fall within the spirit and scope of the various embodiments described herein and the appended claims are included herein.

[0194] Any method disclosed herein need not be performed in the order described. The methods disclosed herein include certain actions taken by a physician; however, the methods may also explicitly or implicitly include any third-party instructions for these actions. For example, an action such as "coupling a transducer module to an ultrasound probe" includes "instructing that a transducer module be coupled to an ultrasound probe". The range disclosed herein also encompasses any and all overlapping ranges, sub-ranges, disclosed values, and combinations thereof. Language such as "at most", "at least", "greater than", "less than", "between..." and similar languages ​​include the listed numbers. Numbers preceded by terms such as "about" or "approximately" include the listed numbers. For example, "about 25 mm" includes "25 mm". For convenience, titles and / or headings are provided herein, and they do not limit the claimed subject matter.

Claims

1. An ultrasound therapy system, comprising: An ultrasound probe, comprising a housing, the housing comprising a piezoelectric active ultrasound therapy transducer, the piezoelectric active ultrasound therapy transducer being adapted to focus acoustic ultrasound waves into a focal zone in tissue at a depth from the housing; an electrical power system configured to provide electrical power to the ultrasonic therapy transducer, the electrical power system comprising a power amplifier; and an electrical power measurement system configured to monitor the electrical output power of an output signal from the power amplifier, Among them, the electric power measurement system includes: a resistive current sensing circuit configured to monitor current output from the power amplifier; and a resistive voltage sensing circuit configured to monitor a voltage output from the power amplifier, and Wherein the electrical power measurement system is configured to monitor the electrical output power from the power amplifier over a frequency range spanning at least two octaves for an ultrasonic therapeutic transducer.

2. The system according to claim 1, wherein: The measurement system is configured to perform a plurality of measurements at different relative phase shifts between the local oscillator and the power amplifier.

3. The system according to any one of claims 1 to 2, wherein: The local oscillator clock is generated from an independently controlled direct digital synthesizer.

4. The system according to any one of claims 1 to 2, wherein: The number of phase measurements is 6.

5. The system according to any one of claims 1 to 2, wherein: The measurement system is configured to make a plurality of measurements at a local oscillator frequency.

6. A system using a measurement system according to any one of claims 1 to 5 to modify a gate drive signal in order to achieve a desired harmonic content in an output signal.

7. An ultrasound therapy system, comprising: An ultrasound probe, comprising a housing, the housing comprising a piezoelectric active ultrasound therapy transducer, the piezoelectric active ultrasound therapy transducer being adapted to focus acoustic ultrasound waves into a focal zone in tissue at a depth from the housing; an electrical power system configured to provide electrical power to the ultrasonic therapy transducer, the electrical power system comprising a power amplifier; and an electrical power measurement system configured to monitor the electrical output power of an output signal from the power amplifier, Among them, the electric power measurement system includes: a resistive current sensing circuit configured to monitor a current output from the power amplifier, and Wherein the electrical power measurement system is configured to monitor the electrical output power from the power amplifier over a frequency range spanning at least two octaves for an ultrasonic therapeutic transducer.

8. The system according to claim 7, wherein: The measurement system is configured to perform a plurality of measurements at different relative phase shifts between the local oscillator and the power amplifier.

9. The system according to any one of claims 7 to 8, wherein: The local oscillator clock is generated from an independently controlled direct digital synthesizer.

10. The system according to any one of claims 7 to 8, wherein: The number of phase measurements is 6.

11. A system for modifying a gate drive signal using a measurement system according to any one of claims 7 to 10 in order to achieve a desired harmonic content in an output signal.

12. A method of controlling electrical power in an ultrasonic system for delivering a desired amount of focused acoustic power through an ultrasonic transducer, the method comprising: An electric power control system is provided, comprising a circuit including a control system microprocessor and a control system look-up table (LUT); Providing an ultrasonic transducer including a transducer controller, a transducer microprocessor, and a transducer LUT; determining, using the transducer microprocessor from the transducer LUT, an amount of electrical power to be delivered to a load that is equal to a desired amount of acoustic power to be delivered to tissue by the ultrasonic transducer; determining, using the control system microprocessor from the control system LUT, the amplitude of the electrical signal output from the power amplifier of the electrical power system that will deliver an equal amount of electrical power delivered to the load; and At least one parameter of the electrical power system output is set to the determined amplitude of the electrical signal output.

13. The method of controlling electrical power in an ultrasonic system according to claim 12, wherein: The load is 50 ohms.

14. A method of controlling electrical power in an ultrasonic system for delivering a desired amount of focused acoustic power through an ultrasonic transducer to calculate composite harmonic components of voltage and current waveforms by forming a linear combination of the multiple measurements of claim 12.

15. A method of controlling electrical power in an ultrasonic system for delivering a desired amount of focused acoustic power through an ultrasonic transducer, the method comprising: An electric power control system is provided, comprising a circuit including a control system microprocessor and a control system look-up table (LUT); Providing an ultrasonic transducer including a transducer controller, a transducer microprocessor, and a transducer LUT; determining, using a transducer microprocessor from a transducer LUT, an amount of electrical power to deliver to a load that is equal to a desired amount of acoustic power to be delivered to tissue by the ultrasonic transducer; determining, using a control system microprocessor from a control system LUT, an amplitude of an electrical signal output from a power amplifier of an electrical power system that will deliver an equal amount of electrical power delivered to a load; and setting at least one parameter of the electrical power system output to the determined amplitude of the electrical signal output, Wherein, the load is in the range of 20 to 120 ohms.

16. A system for measuring radio frequency (RF) current and voltage of a driving circuit in a high intensity focused ultrasound system, comprising: A current sensing resistor, connected in series with the load; a shunt voltage sensing resistor network connected in parallel with the load; and An electrical power output voltage and current monitoring circuit (IQ demodulator circuit) having a local oscillator clock synchronized in phase and frequency with a signal driving the power amplifier and configured to demodulate the output signal to a carrier frequency lower than the ultrasonic drive frequency.

17. The system of claim 16, wherein: The measurement system is configured to perform a plurality of measurements at different relative phase shifts between the local oscillator and the power amplifier.

18. A system according to any one of claims 16 to 17, wherein: The local oscillator clock is generated from an independently controlled direct digital synthesizer.

19. A system according to any one of claims 16 to 17, wherein: The number of phase measurements is 6.

20. The system according to any one of claims 16 to 17, wherein: The measurement system is configured to make a plurality of measurements at a local oscillator frequency.

21. A system for modifying a gate drive signal using a measurement system according to any one of claims 16 to 20 in order to achieve a desired harmonic content in an output signal.

22. A system for measuring radio frequency (RF) current and voltage of a driving circuit in a high intensity focused ultrasound system, comprising: A current sensing resistor, connected in series with the load; a shunt voltage sensing resistor network connected in parallel with the load; and An electrical power output voltage and current monitoring circuit (IQ demodulator circuit) having a local oscillator clock synchronized in phase and frequency with a signal driving the power amplifier and configured to demodulate the output signal to a carrier frequency.

23. The system of claim 22, wherein: The measurement system is configured to perform a plurality of measurements at different relative phase shifts between the local oscillator and the power amplifier.

24. A system according to any one of claims 22 to 23, wherein: The local oscillator clock is generated from an independently controlled direct digital synthesizer.

25. The system according to any one of claims 22 to 23, wherein: The number of phase measurements is 6.

26. A system for modifying a gate drive signal using a measurement system according to any one of claims 22 to 25 in order to achieve a desired harmonic content in an output signal.

27. A method for calibrating a high intensity ultrasonic transducer, comprising: calibrating an acoustic output power delivered by a transducer for a driver configuration, the acoustic output power corresponding to an electrical power delivered by the driver into one or more reference loads for the driver configuration, wherein calibration information is stored by the transducer; and The electric drive configuration is calibrated against electrical power delivered to one or more reference loads, wherein the calibration information is stored by the drive.

28. The method according to claim 27, wherein: The transducer calibration information also includes electrical power delivered to the transducer at each acoustic power level, wherein the stored power information includes a complex power component or a real power component.

29. The method of any one of claims 27 to 28, further comprising performing calculations using a processor of a driver configuration to achieve a desired acoustic output power, the processor using transducer calibration information to determine power levels into one or more reference loads for a desired acoustic power setting, and using the driver calibration information to determine a driver configuration for the desired acoustic output power level into the reference loads, wherein Dynamic measurements of electrical power delivered from the driver are made during tissue insonification and verified against electrical power stored in the transducer calibration for desired acoustic power levels.

30. The method according to any one of claims 27 to 28, in, The transducer calibration information also includes electrical power delivered to the transducer at each acoustic power level, wherein the stored power information includes a complex power component or an actual power component; a processor utilizing a driver configuration to perform calculations to achieve a desired acoustic output power, the processor using transducer calibration information to determine power levels into one or more reference loads for a desired acoustic power setting, and using the driver calibration information to determine a driver configuration for the desired acoustic output power level into the reference loads; Therein, dynamic measurements of electrical power delivered from the driver are made during tissue insonification and verified against electrical power stored in the transducer calibration for desired acoustic power levels.

31. The method according to any one of claims 27 to 28, in, The transducer calibration information also includes electrical power delivered to the transducer at each acoustic power level, wherein the stored power information includes a complex power component or an actual power component; wherein dynamic measurement of electrical power delivered from the driver is made during tissue insonification and verified against electrical power stored in the transducer calibration for a desired acoustic power level; wherein the acoustic output power is generated by performing a measurement using a force balance; wherein the transducer calibration is stored as a lookup table in a non-volatile memory chip inside the transducer; wherein at least one of a voltage or a current measured at the driver is adjusted using a transfer matrix describing a two-port network between a therapy drive circuit output and the transducer; Wherein, the calibration information is stored in a lookup table (LUT); Therein, the target voltage is calculated from calibration information and the desired acoustic power set in the clinic by interpolating values ​​in one or more lookup tables.

32. The method according to any one of claims 27 to 28, wherein: The acoustic output power is generated by performing measurements using a force balance.

33. The method according to any one of claims 27 to 28, wherein: The transducer calibration is stored as a look-up table in a non-volatile memory chip within the transducer.

34. The method according to any one of claims 27 to 28, wherein: At least one of a voltage or a current measured at the driver is adjusted using a transfer matrix describing a two-port network between the therapy drive circuit output and the transducer.

35. The method according to any one of claims 27 to 28, wherein: The calibration information is stored in a look-up table (LUT).

36. The method of claim 35, wherein: A target voltage is calculated from the calibration information and the desired acoustic power set in the clinic by interpolating values ​​in one or more lookup tables.

37. A storage method for storing an electric power threshold at each acoustic power level in the transducer calibration information, wherein the electric power threshold defines an acceptable range of electric drive power to obtain an acceptable range of acoustic output power of claim 27.

38. A system for confirming that dynamically measured electrical power is within the range specified in claim 36, comprising dynamically measuring the power delivered by a driver and comparing said power to a threshold value stored in a transducer.

39. The method of claim 34, wherein: The transfer matrix of the hand piece and cable assembly that is capable of interchange between transducers and drivers is stored on a non-volatile memory chip within the hand piece and the cable assembly.

40. A method for dynamically adjusting power, comprising: Measuring the electrical power delivered from the drive; comparing the measured electrical power to the desired electrical power determined from the calibration information of claim 27, and The driver configuration is adjusted to reduce the error between the desired electrical power and the measured electrical power.

41. A method for calibrating a high intensity focused ultrasound transducer, comprising: The driver is modeled as a Thevenin equivalent source with frequency-dependent source voltage and source impedance, and calibration information including source voltage and source impedance is stored using the driver, measuring the transducer impedance and storing the transducer impedance in calibration information on the transducer, and The electrical power delivered by the driver to the transducer is calculated using the source voltage and source impedance stored in the driver calibration to the load impedance stored in the transducer calibration, and treating the combined system as a voltage divider network.

42. A method for dynamically adjusting power, comprising: Measuring the electrical impedance of the load and calculating the transducer impedance based on the known impedances of other system components; calculating the required electrical power from the driver to maintain the same amount of dissipated power at the actual transducer impedance; and The drive configuration is adjusted to meet the electrical power required to reduce the error between the desired electrical power and the measured electrical power.

43. A method according to any one of claims 40 to 42, wherein: The power is dynamically adjusted whenever therapy is delivered.

44. A method of tuning a high intensity focused ultrasound transducer, the method tuning the high intensity focused ultrasound transducer by sweeping the frequency while measuring a voltage standing wave ratio at a driver and selecting the frequency that minimizes the voltage standing wave ratio as an operating frequency. 45.A method for measuring transducer impedance: calibrating the driver using one or more known reference impedances; measuring the impedance of the transducer at one or more frequencies and one or more amplitudes; Installing the measured transducer into a resonant circuit in order to calculate the transducer parameters; Use characterization to determine transducer life, operational acceptability, and required amplitude and phase.

46. ​​The method of claim 45, wherein: The transducer parameters include clamping capacitance, coupling coefficient and radiation resistance.

47. The method of claim 45, wherein: The distance between the transducer and the intended treatment area is fixed.

48. The method of claim 47, wherein: The treatment beam is temporarily moved to an untreated area to determine the amount of backscatter from the treatment area using a differential method.

49. The method of claim 45, wherein: The transducer impedance is measured by using shorter duration excitation pulses to eliminate backscatter or reflections from the tissue or transducer interface.

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