Method and system for detecting acoustic coupling failure between an ultrasound device and treated tissue - Patents.com

Abstract

The present invention provides an apparatus for treating a medical condition, comprising: an ultrasonic generating device (1); - a remote control unit (2) for supplying electricity to said device (1); - electrical connection means (31, 32) between said device (1) and said control unit (2); It is equipped with The control unit (2) is programmed to evaluate the quality of acoustic coupling between the ultrasound device (1) and the tissue to be treated.

Description

[Technical field]

[0001] The present invention relates to the general technical field of ultrasound devices, for example internal or implantable devices, intended to be electrically connected to a remote control unit.

[0002] Such devices may be implanted in humans and mammals, among other things, to assist practitioners in establishing a diagnosis and / or treating a medical condition. [Background technology]

[0003] A device for treating brain disorders is known from document WO20158 / 007500. With reference to FIG. 1, such a device comprises: an ultrasonic device 1 made of a non-ferromagnetic material; a control unit 2 located remotely from the ultrasound device 1; - connection means for the connection between the ultrasound device 1 and the control unit 2; It is composed of:

[0004] The ultrasound device 1 is intended to be placed in a burr hole formed in the patient's skull. The ultrasound device 1 is advantageously compatible with magnetic resonance imaging (MRI) technology. - at least one transducer 12 for the generation of ultrasound waves for treating brain diseases; - fixing means 13 for fixing the transducer 12 to the patient's skull; - one (or more) electrical connection terminals 14 intended to cooperate with the connection means.

[0005] The control unit 2 is intended to supply electrical energy to the ultrasonic device 1 and to regulate its operating parameters.

[0006] The connection means are intended to electrically couple the ultrasound device 1 to the control unit 2. The connection means generally comprise: - one (or more) electrical connection cables 31, one end of which is connected to the control unit; - one (or more) percutaneous needles 32 connected to the other end of the cable 31; It is equipped with:

[0007] The principle of operation of this device is as follows: once the ultrasonic device 1 is implanted in the patient's skull, a series of treatment sessions are provided to the latter in order to treat a pathology affecting the patient. For each new treatment session, the ultrasonic device 1 is linked to the control unit 2 via a connection means.

[0008] The practitioner connects the cable 31 to the control unit 2 and then inserts the needle 32 through the patient's skin to the terminal 14 of the ultrasound device.

[0009] When the end of the needle 32 is connected to the terminal 14 , the control unit 2 is activated and electrical energy can be supplied to the ultrasound device 1 .

[0010] The detection method described in WO2018 / 007500 proposes checking the quality of the electrical connection between the ultrasound device 1 and the control unit 2 prior to the performance of the treatment.

[0011] More specifically, the systems and methods described in WO2018 / 007500 include: - the absence of an electrical connection between the cable 31 and the control unit 2, - the absence of an electrical connection between the percutaneous needle and the terminal 14 This allows different types of defective electrical connections to be detected.

[0012] Checking the quality of the electrical connection between the ultrasound device 1 and the control unit 2 before the performance of the treatment makes it possible to limit the risk of ineffective treatment.

[0013] However, other parameters may affect the effectiveness of the treatment, in particular the quality of the acoustic coupling between the ultrasound device 1 and the tissue being treated.

[0014] One object of the present invention is to: an ultrasonic device; - The tissue to be treated and The object of the present invention is to propose a method and a system which allows the practitioner to detect possible defects in the quality of the acoustic coupling between the

[0015] Ultrasonic devices may deteriorate over time, and in particular the operation of one (or more) transducers of the device may fail if, for example, the electrical connections of one (or more) transducers are altered (shorted or open circuited), for example upon release of one (or more) connection tabs from one (or more) transducers.

[0016] Another object of the invention is to propose a method and a system that allows the practitioner to detect malfunctions of one (or more) transducers of an ultrasound device. Summary of the Invention

[0017] To this end, the present invention provides an apparatus for treating a medical condition, comprising: an ultrasonic device comprising at least one transducer capable of generating ultrasonic waves, the transducer having a front face intended to be located opposite the target medium; - a remote control unit for determining and monitoring the operating parameters of the ultrasound device and for supplying it with electricity during at least one treatment cycle, each treatment cycle being followed by a standby cycle; - Electrical connection means between the ultrasonic device and the control unit; It is equipped with The control unit is programmed to perform an estimation phase of the quality of acoustic coupling between the ultrasonic device and the target medium, said estimation phase comprising: - emission by the control unit of at least one monitoring signal, each monitoring signal having a respective frequency; - measuring at least one reflected signal by the control unit, each reflected signal corresponding to a respective monitoring signal; - The presence of liquid in the ultrasonic device, or ◯ and the presence of reflective material, such as air bubbles, between at least one transducer and the target medium. and processing the reflected signal to detect either The present invention proposes an apparatus comprising:

[0018] Preferred, but non-limiting aspects of the present invention are as follows: The estimation phase may comprise a step of detecting the presence of liquid in the ultrasonic device, which step comprises the following sub-steps: - emission of a leakage current monitoring signal at a leakage current monitoring frequency by the control unit; - measuring by the control unit a reflected leakage current monitoring signal corresponding to a portion of the leakage current monitoring signal that is not absorbed by the ultrasonic device; Processing reflected leakage current monitoring signals to detect the presence of liquid in the ultrasonic device; Includes; the leakage current monitoring frequency may be a frequency that does not belong to the operating frequency range of the transducer, in particular a frequency of about 600 kHz for a transducer whose operating frequency is equal to 1 MHz; The estimation phase may comprise a step of detecting the presence of an air bubble, which step comprises the following sub-steps: - the emission by the control unit of a gas monitoring signal at a gas monitoring frequency; - measuring by the control unit a reflected gas monitoring signal corresponding to a portion of the gas monitoring signal that is not absorbed by the ultrasonic device; Processing the reflected gas monitoring signal to detect the presence of air bubbles between the transducer and the target medium; Includes; the bubble monitoring frequency may be a frequency belonging to the operating frequency range of the transducer, more particularly a frequency greater than 90% of the working frequency of the transducer, in particular a frequency of about 962 kHz for a transducer whose working frequency is equal to 1 MHz; - a step of detecting the presence of an air bubble may be performed for each transducer during at least one waiting cycle, said step comprising: activating each transducer in which no air bubbles have been detected, such that the activated transducer is capable of supplying electrical energy for the generation of ultrasonic therapeutic waves during at least one treatment cycle after said and at least one waiting cycle; deactivating each transducer in which an air bubble is detected, such that the deactivated transducer does not deliver electrical energy during the treatment cycle and during at least one subsequent waiting cycle; The method further comprises the steps of: - each treatment session may include multiple treatment cycles during which the device transmits ultrasonic therapeutic waves towards the tissue to be treated, each treatment cycle being followed by a waiting cycle, the control unit: Detecting the presence of an air bubble during each waiting cycle; Detecting the presence of fluid during each treatment cycle; be programmed to carry out the - the steps of detecting the presence of liquid and gas may be performed successively, the step of detecting the presence of liquid being performed after the step of detecting the presence of gas bubbles; The ultrasonic device may comprise a casing in which each transducer is housed, the casing comprising a bottom facing a front face of each transducer, the bottom being made of poly-ether-ether-ketone and having a thickness comprised between 0.3 mm and 0.8 mm, preferably comprised between 0.3 and 0.6 mm, and even more preferably substantially equal to 0.4 mm ± 0.05 mm, for an operating frequency of the transducers equal to 1 MHz.

[0019] The estimation phase may include a step of detecting the operation of each transducer, in particular a step of detecting a short circuit or an open circuit. For this purpose, the control unit detects the frequency F 0 A voltage is sent to each transducer at a frequency of 100 kHz, this frequency being advantageously zero (DC voltage).

[0020] The present invention provides an implantable ultrasound device comprising at least one transducer capable of generating ultrasound waves, the transducer comprising: at least one electroacoustic element made of piezoelectric material, a casing with a bottom, at least one side wall and a top wall, the casing forming a sealed housing intended to contain said and at least one electroacoustic element; It is equipped with An implantable ultrasound device is also proposed, characterized in that the material constituting the bottom of the casing is poly-ether-ether-ketone (PEEK).

[0021] Preferred, but non-limiting aspects of the present invention are as follows: - the electroacoustic element comprises a front surface intended to lie opposite the tissue to be treated and a rear surface opposite the front surface, the transducer comprises a layer that reflects acoustic waves, such as a layer of air, said layer extending over the rear surface of the electroacoustic element; Hereinafter, when a layer A is referred to as "extending" a layer B, it is understood that this latter may be directly on layer B or may be separated from said layer B by one or more intermediate layers located on top of layer B and playing a negligible acoustic role at the operating frequency of the transducer; - the front surface of the electroacoustic element is in contact with the bottom of the casing; In the following, when layer A is referred to as being "in contact with" layer B, it is understood that this latter may be in direct contact with layer B or may be separated from said layer B by one or more intermediate layers that play a negligible acoustic role at the operating frequency of the transducer; - the material constituting said and also at least one side wall and cover of the casing is poly-ether-ether-ketone (PEEK); - The thickness of the bottom of the casing must satisfy the following relationship: E Bottom =(V sound / 4F Working )×(0.8±0.4) (In the formula, -E Bottom corresponds to the thickness of the bottom of the casing (mm), -V sound corresponds to the speed of sound in the material that makes up the bottom of the casing, - F Working corresponds to the operating frequency (in MHz) of the transducer 12, said operating frequency being chosen in the normal frequency band of the transducer 12) Satisfied, For an operating frequency of about 1 MHz, the thickness of the PEEK bottom is chosen between 0.3 mm and 0.8 mm, preferably between 0.3 mm and 0.6 mm, and even more preferably substantially equal to 0.4 mm (±0.05 mm).

[0022] The present invention provides an apparatus for treating a medical condition, comprising: an ultrasonic device comprising an electronic card and at least one transducer electrically connected to the electronic card, the transducer being capable of generating ultrasonic waves; - a remote control unit for determining and monitoring the operating parameters of the ultrasound device and for supplying it with electricity during at least one treatment cycle, each treatment cycle being followed by a standby cycle; - Electrical connection means between the ultrasonic device and the control unit; It is equipped with The control unit is programmed to perform a detection phase of malfunction of each transducer of the ultrasonic device, the detection phase comprising: - emission by the control unit of at least one test signal, each monitoring signal having a zero frequency; - measuring, by the control unit, at least one reflected test signal; - A short circuit in the ultrasonic device, or - Poor electrical connection between said and at least one transducer and the electronic card and processing the reflected test signal to detect either The present invention proposes an apparatus comprising:

[0023] Other advantages and characteristics of the method and system according to the invention will become more apparent from the following description of some variants of embodiments shown by way of non-limiting example and from the accompanying drawings, in which: [Brief description of the drawings]

[0024] [Figure 1] 1 shows a schematic of one example of an apparatus for treating brain conditions, including an ultrasound device electrically connected to a remote control unit by a connection means (percutaneous needle + cable). [Diagram 2] 1 is a schematic partial representation of one of the transducers of an ultrasonic device. [Diagram 3] 1 shows the power absorption spectrum of a therapeutic transducer. [Figure 4] FIG. 2 is a schematic diagram of the main steps of a method for estimating the quality of an acoustic coupling. [Diagram 5] 1 is a curve showing the power consumed by each transducer as a function of the frequency of an applied electrical signal for a batch of transducers. [Figure 6] FIG. 2 is a schematic diagram of an alternative embodiment of a method for estimating the quality of acoustic coupling. [Figure 7] 1 is a schematic diagram of an alternative embodiment of a method for detecting transducer operational faults. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Different examples of systems and methods for estimating the quality of acoustic coupling are described with reference to the figures, in which equivalent elements are designated by the same reference numbers.

[0026] The estimation system and method allows a practitioner to verify whether accurate acoustic coupling between an ultrasound device implanted within a patient's body and the tissue being treated has been achieved.

[0027] In the following, the estimation system and method will be described with reference to the device shown in document EP 2539021, which refers to international application WO 2018 / 007500.

[0028] However, it will be apparent to one skilled in the art that the systems and methods according to the present invention may be implemented with any type of treatment device, including implantable or non-implantable devices that are acoustically coupled to the tissue being treated.

[0029] 1. general concept 1.1. treatment equipment As previously mentioned, the device: - an ultrasonic device 1; - a remote control unit 2; - Connection means and It is equipped with:

[0030] The ultrasound device 1 is intended to be implanted in the skull of a patient. It: - an electronic card suitable for replacing the power supply and for monitoring the electrical signals with a remote control unit; a transducer 12 connected to an electronic card for generating ultrasonic waves; a connection terminal 14 intended to receive a percutaneous needle 32 of an electrical connection means; It is equipped with:

[0031] In the following, the ultrasonic device 1 is embedded, i.e.: - an ultrasound device 1 is inserted into the cranial opening so that the transducer is extended against the tissue to be treated, The ultrasound device 1 is fixed around the cranial opening by any means known to the person skilled in the art (anchor screws, glue, etc.) and then - The patient's scalp and head muscles are repositioned to cover the ultrasound device 1 It is thought that.

[0032] A remote control unit 2 makes it possible to supply electrical energy to the ultrasonic device 1, to adjust its operating parameters and to receive the signals reflected by the device. Such control units 2 are known to those skilled in the art and will not be described in more detail below.

[0033] The connection means allow an electrical coupling between the ultrasound device 1 and the control unit 2. The connection means may in particular comprise: - a percutaneous needle 32 that can be plugged onto a connection terminal of an ultrasound device; - a conductive cable 31; - a mating socket (not shown) that can be plugged into a complementary socket on the control unit 2; It is equipped with:

[0034] 1.2. Principle of using the device Such devices allow the treatment of brain disorders by carrying out several treatment sessions supervised by a practitioner.

[0035] At each new treatment session, the practitioner electrically connects the ultrasound device 1 to the remote control unit 2 by using the connection means.

[0036] More specifically, the practitioner connects the link socket to the remote control unit 2. Next, the practitioner inserts the percutaneous needle 32 into the patient's scalp and introduces the end of the needle 32 into the blind hole of the connection terminal 14 to complete the electrical connection of the ultrasound device 1 to the remote control unit 2.

[0037] Once the ultrasound device 1 is connected to the control unit 2, a series of treatment cycles are performed, each treatment cycle being followed by a wait cycle.

[0038] During the standby cycle, the ultrasonic device 1 is deactivated for a standby period (approximately 1 second) by not supplying electrical energy to the ultrasonic device 1.

[0039] Once the waiting period has ended, a treatment cycle is performed during which the ultrasound device 1 is electrically energized by application of an electrical excitation signal at the connection terminals for a treatment period (approximately 25 milliseconds).

[0040] This electrical excitation signal is emitted by the control unit 2 at the operating frequency of the transducer 12 .

[0041] In the present invention, the "operating frequency" (or "treatment frequency") refers to the transmission frequency of the ultrasonic treatment waves emitted by the transducer 12, which also corresponds to the frequency of the electrical excitation signal that makes it possible to supply electrical energy to the ultrasonic device.

[0042] This operating frequency is within the useful frequency band of the transducer 12 (i.e., the operating frequency range of the transducer), and the transducer 12 will not move (i.e., will not generate ultrasound) when an electrical signal is applied to it whose frequency is not within this useful band.

[0043] Advantageously, the transducer 12 may be selected to have maximum efficiency at an operating frequency that corresponds to the therapeutic frequency of the ultrasound used to treat the tissue being treated.

[0044] In response to application of an electrical excitation signal during a treatment session, the transducer 12 generates ultrasonic waves in the direction of the tissue to be treated.

[0045] Once the treatment period has ended, for example until the end of the session, a new waiting cycle is implemented.

[0046] 2. Transducer Referring to FIG. 2, a partial cross-sectional view of an example of a transducer 12 of an ultrasonic device 1 is shown.

[0047] The transducer 12: - one (or more) electroacoustic elements 121 intended for therapy (the pulse trains are long and of fixed frequency); a casing 122 for housing the electroacoustic element; It is equipped with:

[0048] 2.1. Electroacoustic Element Each electroacoustic therapy element 121 is made of a piezoelectric material, for example a "composite material" (a combination of at least one piezoelectric material with one or more non-piezoelectric materials, such as a polymer).

[0049] If the piezoelectric element 121 is of the "composite" type, its acoustic impedance is close to that of tissue and a quarter wave plate is not necessary, especially if the device is intended for treatment.

[0050] Each electro-acoustic element 121 is fixed to the bottom 1221 of the casing 122, for example by being glued by using a thin adhesive layer (which plays a negligible acoustic role at the operating frequency of the transducer).

[0051] As shown in FIG. 2, the transducer 12 also comprises a reflective layer (or backing), e.g. one (or more) layers of air 123, on the rear surface 1212 of the electro-acoustic element 121, with the layer (or each layer) of air 123 extending over the rear surface 1212 of the electro-acoustic element 121.

[0052] Therefore, unlike acoustic imaging devices (using a technique known as the "pulse-echo" technique) in which the rear surface of each electro-acoustic element is covered with an absorbing material that prevents the element from resonating long after its excitation, transducer 12 does not have an absorbing material on the rear surface 1212 of electro-acoustic element 121.

[0053] Finally, the therapeutic transducer transmits high energy (especially due to the duration of transmission) and therefore must not increase in temperature, especially when this is performed in a patient.

[0054] Therefore, the presence of absorbing material is undesirable at the rear surface of the electroacoustic element 121 of the transducer 12 .

[0055] The reader will also understand that a layer of air placed on the rear face of the electroacoustic element 121 makes it possible to improve the energy efficiency of the transducer by reflecting all the acoustic energy generated by the element towards its front face.

[0056] In fact, the piezoelectric element 121: a front surface 1211 directed towards the tissue to be treated; - The rear surface 1212 opposite the front surface 1211 It is equipped with:

[0057] When element 121 is supplied with electrical energy, it converts the electrical energy into mechanical energy, and its vibration generates acoustic waves that can propagate forward and backward through the element.

[0058] The layer of air 123 on the rear face 1212 of the piezoelectric element acts as a mirror and reflects the rearward bound waves of the element 121 towards its front face 1211. In this way, losses of part of the mechanical energy generated by the element 121 are avoided.

[0059] 2.2. Casing The casing 122 comprises a bottom 1221, a side wall and a cover 1222. Advantageously, the material of which the casing 122 is made may be poly-ether-ether-ketone (hereinafter referred to as "PEEK"). PEEK is particularly suitable for the manufacture of implantable devices due to a number of its properties. PEEK is in fact: - Highly sealed, - It is biocompatible; - electrically insulating, and - Stable over time (when immersed) Materials.

[0060] In the embodiment shown in FIG. 2, for an operating frequency of about 1 MHz, the thickness of the bottom part 1221 of the PEEK (facing the front face of the element 121 (or each element 121)) is selected to be between 0.3 mm and 0.8 mm, preferably between 0.3 mm and 0.6 mm, and even more preferably substantially equal to 0.4 mm (±0.05 mm).

[0061] Of course, the selection of the bottom thickness is a function of the operating frequency used for the transducer 12. Thus, the selection of thickness as a function of operating frequency is governed by the following relationship: E Bottom =(V sound / 4F Working )×(0.8±0.4) (In the formula, -E Bottomcorresponds to the thickness of the bottom of the casing (mm), -V sound corresponds to the speed of sound in the material that makes up the bottom of the casing, - F Working corresponds to the operating frequency (in MHz) of the transducer 12, said operating frequency being chosen in the normal frequency band of the transducer 12) Satisfy.

[0062] Such a choice of thickness for the bottom 1221 of the casing 122 is: - to limit the absorption of the ultrasonic energy emitted by the element 121 by the bottom of the casing 122; and - To reduce the volume of implantable ultrasound devices This is in contrast to the general knowledge of those skilled in the art who would choose the thinnest possible bottom thickness.

[0063] On the contrary, this selection of the bottom thickness 1221 (in the case of a PEEK bottom) facilitates detection of insufficient acoustic coupling between the ultrasonic device 1 and the tissue being treated.

[0064] Indeed, the use of a PEEK bottom 1221 with a thickness substantially equal to 0.4 mm (±0.05 mm) facilitates the detection of air bubbles between the transducer 12 and the tissue to be treated; the electrical absorption spectrum is very different depending on whether the bottom is in acoustic contact with gas on the one hand, or with the propagation medium (in this case: the dura) on the other hand.

[0065] The transducer 12 may comprise several piezoelectric elements 122 mounted in the same casing 122. Each casing is hermetically sealed.

[0066] As an indication, FIG. 3 shows the absorption spectrum of the power (effective power) of a transducer coupled to a bottom casing 1221 of different thicknesses. a0corresponds to the power absorbed by the transducer for an incident power of 250 mW. Note that an electrical impedance match is inserted between the transducer and the generator: - the first absorption spectrum (designated 311 for acoustic coupling with the propagation medium and 312 for acoustic coupling with the gas) corresponds to a transducer coupled with a PEEK bottom of thickness equal to 0.4 mm; - the second absorption spectrum (denoted 321 for acoustic coupling with the propagation medium and 322 for acoustic coupling with the gas) corresponds to a transducer coupled with a PEEK bottom of thickness equal to 0.2 mm; - The third absorption spectrum (denoted by 331 for acoustic coupling to the propagation medium and 332 for acoustic coupling to a gas) corresponds to a transducer coupled to a zero thickness PEEK bottom, referred to as a bottom-less casing (the front surface of the transducer is only coated with a layer of Parylene).

[0067] As is evident from this FIG. 3, with a PEEK thickness of 400 μm it is possible to take advantage of transmission at different frequencies to ensure acoustic coupling between the transducer 12 and the tissue to be treated.

[0068] For this reason, for an operating frequency of about 1 MHz, the choice of a PEEK casing 122 whose bottom has a thickness comprised between 0.3 mm and 0.8 mm, preferably comprised between 0.3 mm and 0.6 mm, and even more preferably substantially equal to 0.4 mm (±0.05 mm) is: - Increasing the bandwidth for treatment without reducing the electroacoustic efficiency (a wider frequency range can be used, which is more robust to variations); - Increasing the electrical insulation, biocompatibility and lifespan of ultrasonic devices; in fact, it is known that PZT (lead zirconate titanate) ceramics are not biocompatible (presence of lead), that Parylene (which may be used as a protective film to cover each transducer) is porous, and that PZT or "composite" type materials can be washed away by humidity over time. This makes it possible.

[0069] More generally, the reflected power spectrum (or electrical impedance measurement) can be compared to a reference model or template (consisting of a minimum reference value curve and a maximum reference value curve). If the curve representing the measured reflected power spectrum is not included in the template, this represents a fault. It is possible to define this fault (air, connections, shorts, bad transducer, etc.) by seeing which frequencies the reflected power spectrum lies outside the template.

[0070] "Incident power" means the power transferred by the control unit 2 to the transducer 12. "Real power" means the power consumed by the transducer 12 (incident power - reflected power: some converted to heat, other to ultrasound). "Reflected power" means the power flowing from the transducer 12 to the control unit 2.

[0071] Similarly, the reflected electrical signal (φ r ) and the incident electrical signal (φ 0 ) is defined as the amplitude of the reflected and incident waves.

[0072] The reader may obtain the active power / reflected power / impedance spectrum in several ways, e.g.: Continuously (e.g. over the range 0.2-1.6 MHz), by transmitting a chirp-type frequency modulated test signal or a very short signal and performing a Fourier analysis; or Prudent (limiting the costs of the electronics involved) by emitting several test pulses at different frequencies wisely chosen to make it possible to detect several types of faults from a limited number of pulses at different frequencies (e.g. four pulses at four different frequencies). You will understand that it is possible to obtain

[0073] 2.3. Advantages associated with the above configuration The configuration of the transducer described above (a reflective layer on the rear face of the piezoelectric element, and a PEEK layer on the front face of the piezoelectric element) increases the ability to distinguish between the presence of air and the presence of water at the front face of the transducer, i.e., allows verification of correct coupling when the transducer is implanted. Since the transducer (air + piezoelectric composite + 1 / 4 wave) is very well matched to water and is not attenuated at its rear face, ultrasound can only be attenuated by the front face (water / brain coupling). For this reason, the presence or absence of water on the front face has a very large effect on the electrical impedance of the transducer.

[0074] The transducer also consists of: - improving the bandwidth of the transducer without reducing its electroacoustic efficiency, which allows greater flexibility of use; - Increasing the electrical insulation, biocompatibility and lifespan of the transducer This makes it possible.

[0075] 3. Problems related to the use of therapy devices As indicated above, the quality of the acoustic coupling (between the ultrasound device and the medium containing the tissue being treated) can change over time.

[0076] For example, during a session, air bubbles may form between the transducer 12 (or one of the transducers 12) and the tissue to be treated. Similarly, air bubbles may become trapped between the transducer and the tissue to be treated during the operation of implanting the device. Also, bone mineralization may form over time between the transducer and the tissue to be treated. The presence of such reflective material (air bubbles or bone growths) between the transducer and the tissue limits the propagation of ultrasound waves generated by the transducer 12 towards the tissue to be treated, which results in limiting the effectiveness of the treatment.

[0077] In addition, for example, during insertion of the percutaneous needle 32 into the connection terminal 14, liquid may enter the device 1, which liquid may cause a short circuit (or, more specifically, the appearance of a leakage current) that limits the effectiveness of the treatment.

[0078] This is why it is desirable to estimate the quality of the acoustic coupling between the ultrasound device 1 and the tissue to be treated, in order to limit the risk of ineffectiveness in the treatment.

[0079] Furthermore, one (or more) of the transducers may have a defect such as a short or an open circuit (eg, after one (or more) connection tabs from one (or more) of the transducers open).

[0080] This is why it is also desirable to detect malfunctions of one (or more) transducers of an ultrasound device, in order to limit the risk of ineffective treatment.

[0081] The reader will understand that these two testing phases (i.e., estimating the quality of the coupling and detecting transducer misoperation) can be performed independently of each other or together. To this end, in some embodiments, the treatment device is: - only estimate the quality of the acoustic coupling, or - only detect malfunctions of one (or more) transducers of an ultrasound device, or - To both estimate the quality of acoustic coupling and to detect malfunctions of one (or more) transducers of an ultrasonic device It can be configured as follows.

[0082] 4. Methods for assessing the quality of acoustic coupling With reference to FIG. 4, the method for estimating the quality of acoustic coupling comprises the following steps: - emission 411 of at least one monitoring signal by the control unit 2; - obtaining 412 at least one feedback signal by the control unit 2; - processing 413 of the feedback signal so as to obtain information on the quality of the acoustic coupling between the ultrasound device 1 and the tissue to be treated, said processing comprising: ■ Activation of each transducer 12 whose acoustic coupling quality exceeds a quality threshold; ■ Stopping each transducer 12 whose acoustic coupling quality falls below a quality threshold Enables processing and Includes.

[0083] After evaluation of the quality of acoustic coupling, the activated transducers can be supplied with electrical energy (during each treatment cycle) so that they generate therapeutic ultrasound waves towards the tissue to be treated, while the deactivated transducers, for their part, are not supplied with electrical energy by the control device 2.

[0084] Each monitoring signal is transmitted at a low electrical energy (approximately 1% of the energy required for treatment) compared to the excitation signal. More specifically, the power of each monitoring signal is such that any ultrasound waves generated by the ultrasound device (in response to the monitoring signal) do not cause any effect in any tissue.

[0085] To detect the possible presence of one of these factors (i.e. fluid in the ultrasound device, and / or air bubbles / bones between the bottom of the casing and the propagation medium, and / or malfunction of the transducer), several monitoring signals are emitted, each at one frequency. For each signal, the control unit 2 emits a signal of known amplitude and frequency to the device 1. This signal is not a perfect impedance match, especially due to the imperfect acoustic match between the transducer 12 and the tissue, and part of the signal (feedback signal) is reflected back to the device. The control unit 2 measures the amplitude of this reflected signal and infers the reflection coefficient from them. The control unit 2 can also measure the impedance of the circuit up to the transducer of the implantable ultrasound device.

[0086] More specifically, the method comprises the following steps for each transducer 12 of the ultrasonic device 1: - the application of several monitoring signals of several frequencies, each monitoring signal having a respective frequency; - measuring a plurality of reflectances of the monitoring signal, each measured reflectance corresponding to a respective monitoring signal; - comparison of the reflectivity with a pre-established threshold and an estimation of the quality of coupling between the considered transducer 12 and the tissue; Includes.

[0087] The reflectance corresponds to the proportion of the monitoring signal that is reflected by the transducer 12. The reflectance of the monitoring signal (B) is the sum of the reflected electrical signal (φ r ) and the incident electrical signal (φ 0 ) ratio: B=φ r / φ 0 It can be defined as:

[0088] In practice, the step of applying the monitoring signals consists of applying in succession two, three or four monitoring signals each having a respective frequency.

[0089] The frequency of the monitoring signal depends on four factors: - Poor electrical connection as proposed in WO2018 / 007500, the presence of air bubbles between the transducer 12 and the tissue to be treated, the presence of fluid in the ultrasound device (e.g., at the connection terminals, including the end of the percutaneous needle 32); - Transducer malfunction (short or open circuit) are chosen to maximize discrimination (of problematic detection sensitivity) for each of

[0090] The frequency selection is based on the population of manufactured transducers: - absorption spectrum, - Standard deviation of the absorption spectrum and This is based on the following:

[0091] In particular, the frequency of the monitoring signal is selected so that the following ratio is maximized: (average water -Kσ water ) / (average air +Kσ air ) (where: - "average", the average of the absorption measurements in the sample population at the frequency considered; "σ", the standard deviation of the absorption measurements in the sample population at the frequency considered (slight variations in the operation of the transducer due to manufacturing tolerances explain the presence of this standard deviation), - "K", an integer between 1 and 3.

[0092] The advantage of using different monitoring signals, each with an individual frequency (related to the choice of thickness of the casing bottom), is that it makes the evaluation method very discriminating with regard to the different factors that may deteriorate the quality of the bond. In other words, the method according to the invention determines whether an insufficient bond quality is due to: - Poor connection and - The presence of air bubbles, or - The presence of fluid; - Malfunction of one of the transducers This allows one to define whether the

[0093] This makes it possible to more accurately inform the practitioner as to the nature of the detected problem, so that the practitioner can implement the most suitable solution to resolve the detected problem.

[0094] 4.1. frequency To determine poor coupling that may make treatment impossible or ineffective, different monitoring signals of different frequencies are emitted, each monitoring signal being at a treatment frequency F 1 and (preferably) have a different frequency.

[0095] 4.1.1. Frequency of monitoring signal for short circuit detection In particular, the monitoring signal for the detection of short circuits or parasitic resistances (due to the presence of liquid at the connection terminals) is generated at a frequency F 2 It will be sent out.

[0096] This frequency F 2 is set to an operating frequency F such that the power dissipated by the transducer is low (less than 40% of the incident power). 1 is selected to be much lower than

[0097] More specifically, the frequency F 2 is chosen outside the useful frequency band of the transducer (i.e., the operating frequency range of the transducer) and is therefore much lower than 1 (the frequency F 2The measured reflectivity (i.e., non-zero power consumption) at 100 Hz indicates the presence of a short circuit due to the presence of liquid in the ultrasonic device.

[0098] In particular, in one embodiment of the present invention, the frequency F of the monitoring signal used for detecting short circuits or parasitic resistances is 2 is substantially equal to 0.6 MHz.

[0099] 4.1.2. Frequency of monitoring signal for detection of poor electrical connection The frequency of the monitoring signal for detecting electrical connection failure (see WO2018007500) is a frequency F 2 A frequency different from F 3 It will be sent out.

[0100] This frequency F 3 is the frequency F 2 and operating frequency F 1 In particular, in one embodiment of the present invention, the frequency F of the monitoring signal used for detecting electrical connection failure is selected between 3 is effectively equal to 850 MHz.

[0101] In particular, the frequency F 3 is chosen so that the power dissipated by the transducer is independent of the medium located in front of the transducer. In other words, the frequency F 3 teeth: On the one hand, the power consumed by the transducer is the largest (in particular, greater than 40% of the incident power of the monitoring signal applied to the transducer); The power consumed by the transducer when its front surface is in contact with gas is substantially equal to the power consumed by the transducer when its front surface is in contact with liquid or tissue. It is selected as follows.

[0102] Therefore, it is practically equal to 1 (at frequency F 3The measured reflectivity (i.e. zero operating (=consumption) power) indicates the absence of an electrical connection between the ultrasonic device 1 (or one of the transducers 12 of the device 1) and the control unit 2.

[0103] 4.1.3. Frequency of monitoring signal for detecting air bubbles The monitoring signal for the detection of air bubbles between the transducer and the tissue to be treated has a frequency F 2 and F 3 A frequency different from F 4 It will be sent out.

[0104] In particular, the frequency F 4 is the power consumed by the transducer: - minimum when the front face of the transducer faces the air bubble (a transducer is considered to be in air if the transmitted power is less than 64% of the incident power, and in water if the opposite is true); and - When the front face of the transducer faces the propagation medium, such as dura, tissue or fluid, up to is selected to be.

[0105] This frequency F 4 is the frequency F 3 Higher than the operating frequency F 1 or slightly lower (i.e., 1% to 10% lower, preferably 1% to 5% lower) than F 1 and is selected.

[0106] In particular, in one embodiment of the present invention, the frequency F of the monitoring signal used for bubble detection 4 is substantially equal to 960 MHz (96% of the operating frequency of the transducer).

[0107] For this reason, the frequencies used for the different monitoring signals are selected to maximize the discrimination between different types of defects that may affect the quality of the treatment, as shown in Figure 5 (which shows the power consumed by a batch of transducers as a function of the frequency of the applied electrical signal and a power of 250 mW).

[0108] 4.1.4. The frequency of the monitoring signal for detecting transducer malfunction (DC voltage: F 0 =0) The monitoring signal for the detection of transducer malfunctions is set at zero frequency F so that the monitoring signal has a DC voltage. 0 It will be sent out.

[0109] For this purpose, a DC voltage monitoring signal can be applied to the implantable ultrasound device by the control unit. 0 The monitoring signal is: - A dead short circuit of the transducer (zero impedance when the transducer is activated), or - Faulty connection chamber (impedance too low when liquid is present, especially if the impedance is too low regardless of whether the transducer is controlled or not, or regardless of the controlled transducer) It is possible to detect either

[0110] This test is performed at frequency F 2 Monitoring signals sent by This allows the completion of the tests described in paragraph 4.1.1. for the detection of short circuits from

[0111] 4.2. Example of implementation of the estimation method The operation principle of the estimation method is explained in more detail with reference to Figure 6. The estimation method: - the presence of air in front of the emitter; - Whether the emitter is working or not - Whether a fluid (e.g. water) is present inside the ultrasonic device and This allows the detection of

[0112] In this embodiment, some detection steps of the method are performed during each waiting cycle and others are performed during each treatment cycle.

[0113] 4.2.1. Wait Cycle During each wait cycle, the method comprises: - a first step of detecting a poor electrical connection; - A second step to detect the presence of air bubbles Includes.

[0114] These first and second steps are performed sequentially for each transducer 12 of the ultrasonic device 1 .

[0115] 4.2.1.1. Poor electrical connection The first step in detecting a poor electrical connection is to: - First monitoring frequency F 3 Transmitting 401 a first monitoring signal at: the first monitoring signal consists, for example, of a pulsed signal of power 250 mW and of a duration equal to 1 ms; the first frequency is selected equal to 850 kHz; - obtaining 402 a first reflected monitoring signal corresponding to a portion of the first monitoring signal that is not absorbed by the ultrasound device, comprising: the acquisition of the first reflected signal may consist of measuring the power of the reflected signal (for example by using a directional coupler) or any other information representative of the power consumed by the transducer; - processing 403 the first reflected monitoring signal to detect a connection failure, comprising: During the processing sub-step, information representative of the power consumed by the transducer is extracted from the first reflected signal, This information representative of the consumed power is compared with a first predefined threshold value corresponding to 40% of the power of the first monitoring signal (i.e. 100 mW for a first monitoring signal of 250 mW): ■ the transducer 12 is not properly connected to the remote control unit 2 if the information representative of the consumed power is below a first threshold value (i.e. detection of the absence of an electrical connection between the transducer and the control unit); ■ Otherwise, the electrical connection between the transducer and the control unit under consideration is functional (i.e. there are no defects in the electrical connection between the transducer and the control unit). And The method includes the sub-steps of:

[0116] 4.2.1.2. Presence of gas The steps for detecting the presence of an air bubble are: - transmitting 404 a second monitoring signal at a second monitoring frequency, comprising: the second monitoring signal consists, for example, of a pulsed signal of power 250 mW and of a duration equal to 1 ms; the second frequency is selected equal to 962 kHz; - acquiring 405 a second reflected monitoring signal, comprising: o Here again, obtaining the second reflected signal may consist in measuring the "power absorbed" by the transducer, or the "reflectance", or the electrical impedance, or any other information representative of the power consumed by the transducer; - processing 406 the second reflected monitoring signal to detect the presence of liquid in the ultrasonic device, comprising: o information representative of the power consumed by the transducer (extracted from the second reflected signal) is compared with a second predetermined threshold value corresponding to 64% of the power of the second monitoring signal (i.e. 160 mW for a second monitoring signal of 250 mW): ■ if the information representative of the consumed power is below a second threshold, the medium present opposite the front face of the transducer is gas (i.e., detection of an air bubble between the transducer and the tissue to be treated); ■ Otherwise, the medium present opposite the front face of the transducer is liquid or tissue (absence of air bubbles). And The method includes the sub-steps of:

[0117] 4.2.1.3. Detecting transducer malfunctions Referring to FIG. 7, the steps of detecting an operation failure are: - transmitting a test signal at the zero monitoring frequency 407; - acquiring 408 a reflected test signal, which may consist of measuring the "power absorbed" by the transducer, or the "reflectance", or the electrical impedance, or any other information representative of the power consumed by the transducer; - processing 409 the reflected test signal so as to detect malfunctions of the transducer, whereby information representative of the power consumed by the transducer (extracted from the reflected test signal) is compared with first and second predetermined test thresholds: ■ if the information representative of the consumed power is below a first test threshold (i.e. zero or very low impedance), the transducer has a short circuit; ■ if the information representative of the consumed power exceeds a second test threshold (i.e. too high or infinite impedance), the connection between the transducer and the electronic card has an open circuit; ■ If not, the transducer is working correctly (no malfunctions). And The method includes the sub-steps of:

[0118] This step of detecting operational faults is subsequently performed for each transducer of the ultrasound device, with transducers for which operational faults are detected being deactivated while transducers that do not have operational faults are activated.

[0119] 4.2.2. Treatment cycle During each treatment cycle, the method includes a third step of detecting the presence of fluid in the ultrasound device.

[0120] This detection step is performed prior to each step of transmitting therapeutic ultrasound with the ultrasound device, such that a step of detecting the presence of fluid is performed prior to each step of supplying electrical energy to a transducer to induce the generation of therapeutic ultrasound.

[0121] The third step in detecting the presence of fluid is: - Third monitoring frequency F 2 transmitting 501 a third monitoring signal at: the third monitoring signal consists, for example, of a pulsed signal of power 500 mW and of a duration equal to 100 μs, the third frequency is selected equal to 600 kHz; - measuring 502 a third reflected monitoring signal corresponding to a portion of the third monitoring signal that is not absorbed by the ultrasonic device; - processing 503 the third reflected monitoring signal so as to detect the presence of liquid in the ultrasonic device, the information representative of the consumed power being compared with a third predefined threshold corresponding to 40% of the power of the third monitoring signal (i.e. 200 mW for a third monitoring signal of 500 mW): o if the information representative of the consumed power is below a third threshold, the ultrasonic device does not contain any fluid (i.e., the absence of a short circuit); Otherwise, the ultrasonic device may contain a fluid that causes a short circuit. And The method includes the sub-steps of:

[0122] Depending on the results of the different tests mentioned above, the control unit 2 commands the ultrasound device 1 to emit therapeutic ultrasound.

[0123] In particular, if no short circuit is detected, the control unit 2 powers the activated transducers 12 of the ultrasonic device 1 for which no coupling failure is detected (transducers that are correctly electrically connected and whose front faces are not extended facing the air bubble). This powering step consists of applying to each activated transducer a power supply signal having a power comprised of 7-8 watts for a duration of 24 ms.

[0124] As an indication, a table is given below summarizing the different frequencies used for carrying out the coupling quality estimation phase and the transducer malfunction detection phase.

[0125] [Table 1]

[0126] The reader is advised that the frequencies and thresholds used for the estimation of the quality of acoustic coupling and for the detection of transducer malfunctions are: - can be identical for all ultrasound devices, or -Can be individualized for each ultrasound device You will understand that.

[0127] This individualization makes it possible to take into account any existing variations between the performance of different transducers, which may be related to the tolerances in the manufacture of the transducers (such as variations in the surface roughness or the thickness of each transducer).

[0128] 5. conclusion The method described above makes it possible to evaluate the quality of the acoustic coupling between the ultrasound device and the tissue to be treated, which also makes it possible to detect any malfunction of the transducer.

[0129] So, for example: - into air bubbles between one (or more) transducers and the tissue to be treated, and / or - A short circuit in the ultrasonic device caused by liquid leakage at its connection terminals It is possible to limit the associated risk of therapeutic ineffectiveness.

[0130] Detection of such faults alerts the practitioner, thereby enabling the practitioner to implement solutions to correct these faults.

[0131] The reader will appreciate that many modifications can be made to the invention described above without physically departing from the novel teachings and advantages set forth herein.

[0132] It is therefore intended that all modifications of this type be incorporated within the scope of the appended claims.

Claims

1. 1. An apparatus for treating a medical condition, comprising: an ultrasonic device (1) comprising at least one transducer (12) capable of generating ultrasonic waves, said transducer having a front surface intended to be located facing a target medium; a remote control unit (2) for determining and monitoring the operating parameters of said ultrasound device (1) and for supplying it with electricity during at least one treatment cycle (50), each treatment cycle (50) being followed by a waiting cycle (40); - electrical connection means (31, 32) between said ultrasonic device (1) and said remote control unit (2); It is equipped with The remote control unit (2) is programmed to perform an estimation phase of the quality of acoustic coupling between the ultrasonic device and the target medium, the estimation phase comprising: - the emission by said remote control unit (2) of at least one monitoring signal, each monitoring signal having an individual frequency; - measurement by said remote control unit (2) of at least one reflected signal, each reflected signal corresponding to an individual monitoring signal; the presence of liquid in said ultrasonic device, or The presence of reflective material, such as air bubbles, between the and at least one transducer and the target medium. processing the reflected signal to detect either Including, The estimation phase includes detecting the presence of liquid in the ultrasonic device, the estimation phase comprising the following sub-steps: - emission by said remote control unit (2) of a leakage current monitoring signal at a leakage current monitoring frequency; - measuring, by said remote control unit (2), a reflected leakage current monitoring signal corresponding to the part of said leakage current monitoring signal that is not absorbed by said ultrasonic device; - processing the reflected leakage current monitoring signal to detect the presence of liquid in the ultrasonic device; Including, The estimation phase includes a step of detecting the presence of an air bubble, the step comprising the following sub-steps: - emission by said remote control unit (2) of a gas monitoring signal at a gas monitoring frequency; - measurement by said remote control unit (2) of a reflected gas monitoring signal corresponding to the part of said gas monitoring signal that is not absorbed by said ultrasonic device; - processing the reflected gas monitoring signal to detect the presence of an air bubble between the transducer and the target medium; An apparatus comprising:

2. The treatment device according to claim 1, wherein the leakage current monitoring frequency is a frequency outside the operating frequency range of the transducer, in particular a frequency of about 600 kHz for a transducer whose operating frequency is equal to 1 MHz.

3. 2. The treatment device according to claim 1, wherein the bubble monitoring frequency is a frequency belonging to the operating frequency range of the transducer, more particularly a frequency greater than 90% of the operating frequency of the transducer, in particular a frequency of about 962 kHz for a transducer whose operating frequency is equal to 1 MHz.

4. The step of detecting the presence of an air bubble is performed for each transducer during at least one wait cycle, the step comprising: - activating each transducer in which no air bubbles have been detected, said activated transducer being capable of providing electrical energy for the generation of ultrasonic therapeutic waves during at least one treatment cycle after said and at least one waiting cycle; - deactivating each transducer in which an air bubble is detected, such that said deactivated transducer does not deliver electrical energy during said treatment cycle and during the treatment cycle following at least one waiting cycle. The further step of The treatment device of claim 3.

5. Each treatment session includes a number of treatment cycles during which the ultrasonic device (1) transmits ultrasonic therapeutic waves towards the tissue to be treated, each treatment cycle being followed by a waiting cycle, and the remote control unit (2) is configured to: - detecting the presence of an air bubble during each waiting cycle; - detecting the presence of liquid during each treatment cycle; 20. The therapeutic device of claim 1, programmed to perform the steps of:

6. 10. The treatment device of claim 1, wherein the steps of detecting the presence of liquid and gas are performed sequentially, the step of detecting the presence of liquid being performed after the step of detecting the presence of gas bubbles.

7. The therapeutic device according to any one of the preceding claims, wherein the ultrasonic device (1) comprises a casing in which each transducer is housed, said casing comprising a bottom facing a front face of each transducer, said bottom being made of poly-ether-ether-ketone and the thickness of said bottom being comprised between 0.3 mm and 0.8 mm for an operating frequency of the transducers equal to 1 MHz.

8. The therapeutic device of claim 7, wherein the thickness of the bottom portion is comprised between 0.3 and 0.6 mm for an operating frequency of the transducer equal to 1 MHz.

9. The therapeutic device of claim 8, wherein the thickness of the bottom portion is substantially equal to 0.4 mm ± 0.05 mm for an operating frequency of the transducer equal to 1 MHz.

10. The ultrasonic device comprises an electronic card to which each transducer is electrically connected, and the remote control unit (2) is further programmed to perform a detection phase of malfunction of each transducer of the ultrasonic device, the detection phase comprising: - emission by said remote control unit (2) of at least one test signal having a zero frequency; - measurement by said remote control unit (2) of at least one reflected test signal; - a short circuit between the electronic card and the transducer, or Poor electrical connection between the electronic card and the transducer processing the reflected test signal to detect either The treatment device of claim 1 .

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