METHOD AND SYSTEM FOR DETECTING AN ELECTRICAL CONNECTION FAULT BETWEEN AN ULTRASONIC DEVICE AND A REMOTE CONTROL UNIT

Abstract

The present invention relates to an apparatus for treating a pathology comprising: - an ultrasound generating device (1), - a remote control unit (2) for delivering electricity to the device (1) during at least one activation cycle and determining and controlling its operating parameters, each activation cycle (50) being preceded by a waiting cycle, - electrical connection means (31, 32) between the device (1) and the control unit (2), remarkable in that the control unit (2) is programmed to detect a fault in the electrical connection between the device (1) and said control unit (2) during at least one waiting cycle.

Description

We will now describe different examples of the detection method with reference to figures 2 to 7. In these different figures, the equivalent elements are designated by the same numerical reference. This detection process allows a practitioner to check whether the electrical connection between an external control unit and an ultrasound device implanted in a patient's body is correctly made. In the following, the detection method will be described with reference to the apparatus presented in document EP 2 539 021. However, it is obvious to those skilled in the art that the method according to the invention can be implemented with any type of treatment device including an ultrasound device - intracorporeal device, implantable device or non-implantable device - which must be electrically connected to a remote control unit. As previously described, the device includes: - an ultrasonic device 1 comprising a housing 11 in which is housed at least one transducer 12 for generating ultrasonic waves, - a remote control unit 2 for supplying electrical energy to the ultrasonic device 1, and adjusting its operating parameters, - connection means (transdermal needle + cable) for electrically connecting the ultrasound device 1 and the control unit 2. This device allows the treatment of a brain condition by implementing several treatment sessions prescribed by the practitioner, each session consisting of a succession of activation cycles each preceded by a waiting cycle. During a standby cycle, the ultrasonic device 1 is deactivated for a standby time (of the order of 975 milliseconds). This deactivation is achieved by not supplying the ultrasonic device 1 with electrical energy. When the waiting time has expired, an activation cycle is implemented. The activation of the ultrasound device 1 is carried out by supplying it with electrical energy for an activation time (of the order of 25 milliseconds). This electrical energy is advantageously emitted by the control unit 2 at a working frequency of the transducer 12. The transducer 12 generates ultrasonic waves towards the brain area located just below the ultrasound device 1. When the activation time expires, a new waiting cycle is implemented, and so on until the end of the session. The detection method described below proposes to use the waiting cycle preceding each activation cycle to detect the quality of the electrical connection between the ultrasonic device 1 and the control unit 2. 1. Method for detecting the quality of an electrical connection between the ultrasonic device and the control unit We will now describe in more detail different variants of implementing the detection method. It is assumed in the following that the ultrasound device 1 has been implanted in the patient's skull and that the practitioner has electrically connected the ultrasound device 1 to the control unit 2. Referring to Figure 2, the detection method comprises the following steps: - During each waiting cycle 40: o The transmission 410 by the control unit 2 of at least one control signal at a first instant of the waiting cycle 40, o The acquisition 420 by the control unit 2 of at least one return signal at a second instant of the waiting cycle 40, o Processing 430 of the return signal to obtain information on the quality of the electrical connection between the ultrasonic device 1 and the control unit 2, - During each activation cycle 50, the emission 51, 52 of a signal as a function of the information obtained on the quality of the electrical connection, said signal consisting of: o an activation signal if the control unit 2 is correctly connected to the ultrasonic device 1, o an alarm signal if the control unit 2 is not correctly connected to the ultrasonic device 1. Each control signal is emitted at a low electrical energy compared to the activation signal (of the order of 1% of the energy required for the treatment). This makes it possible to avoid the risk of the patient overheating during the phase of checking the quality of the electrical connection between the ultrasound device 1 and the control unit 2, particularly in the case of a defective connection. In particular, in the event of a short circuit at the transdermal needle due to contact of its poles with a tissue, the emission of the activation signal may cause an electric shock. Even if this is not necessarily dangerous, it may be painful for the patient and cause the burning of a small area of ​​tissue in the scalp. Thus, the method according to the invention allows the practitioner to check the quality of the electrical connection between the ultrasound device 1 and the control unit 2 prior to each activation phase. This guarantees the effectiveness of the treatment during each activation cycle. Different types of faulty connection can be encountered: - Cable 31 may not be electrically connected to control unit 2, - The transdermal needle 32 may not be electrically connected to terminal 14; in this case, the tip of the needle 32 is in contact: or with an electrical insulator (needle 32 not having passed through the layer of insulating material covering terminal 14), or with an electrical conductor (skin of the skull or fluid circulating in the patient's skull). The two variants of the process described below make it possible to detect these different types of faulty electrical connection. 1.1. First embodiment In a first embodiment illustrated in Figures 3 and 4, the method uses a multi-frequency approach. In particular, in this first embodiment, control signals are emitted at two distinct frequencies. Emitting control signals at different frequencies improves the reliability of the process for detecting faulty electrical connections. Indeed, if a single frequency is used with a tolerance on the reflected power, then: - the reflected power in the case where the needle 32 is correctly connected to the ultrasonic device 1, and - the reflected power in the case where the tip of the needle 32 is in contact with a tissue (which is conductive) may be similar, so that it is difficult to differentiate a correct electrical connection from a faulty electrical connection in which the needle is simply in a conductive medium (the two poles which are located at the tip of the needle then being short-circuited). The multi-frequency approach - i.e. the use of control signals at two distinct frequencies - makes it possible to remove this ambiguity. Indeed, the ultrasonic device has the particularity of presenting an impedance varying according to the frequency of the electrical signal applied to it. Advantageously, the control signals emitted during the waiting cycle 40 are pulsed electric currents, the frequencies chosen for the emission of said control signals being: - A first frequency F1 (for example of the order of 1.05 MHz) chosen in a working frequency range - such as a resonance frequency - of the transducer 12, - A second frequency F2 distinct from the first frequency F1 chosen outside the working frequency range of the transducer 12, so that the majority of the control signal emitted at the frequency F2 by the control unit 2 is reflected towards it. Referring to Figure 3, the method may comprise the following steps: - During waiting cycle 40: o emission 411 of a first low-power pulse control signal at a first frequency F1 chosen from a working frequency range of the transducer 12 of the ultrasonic device 1, and acquisition 421 of a first return signal in response, o transmission 412 of a second low-power pulse control signal at a second frequency F2 chosen outside the working frequency range of the transducer 12, and acquisition 422 of a second return signal in response, o processing 431 of the first and second return signals to detect a possible connection fault, - During activation cycle 50: o emission 51 of an alarm signal if a connection fault is detected, o emission 52 of an activation signal otherwise, the activation signal consisting of a high power pulsed electrical signal emitted at the working frequency F1 of the transducer 12. Advantageously, the acquisition of the first and second return signals may consist of measuring the electrical powers of said return signals, by example using a directional coupler. This helps to limit the complexity of the control unit. In addition to electrical connection defects between the ultrasound device 1 and the control unit 2, the multi-frequency approach can make it possible to detect manufacturing defects in the transdermal needle 32, such as a short circuit at the poles of the needle 32, for example by implementing the method illustrated in FIG. 3 prior to inserting the needle 32 into the patient. Figure 4 illustrates an example of a strategy that can be used to detect a connection fault by implementing the first variant of the method according to the invention. Three control signals 61, 62, 63 - each consisting of a low-power electrical pulse of 100 microseconds duration - are transmitted to the ultrasonic device during each waiting cycle 40: - a first pulse 61 emitted at the frequency F2 chosen outside the working frequency range of the transducer 12, - a second pulse 62 emitted at the frequency F1 chosen in the working frequency range of the transducer 12, - a third pulse 63 emitted at frequency F2. First, second and third return signals are acquired in response to remission of the first, second and third pulses 61, 62, 63. These first, second and third return signals are compared with threshold values ​​contained in a memory of the control unit 2. This comparison makes it possible to determine whether the control unit 2 is correctly connected to the ultrasonic device 1, or whether there is a fault in the electrical connection. If the control unit 2 is correctly connected to the ultrasound device 1, an activation signal 71 at the frequency F1, of high power (i.e. power greater than the power of the control signals) and of a duration of 23.8 microseconds is emitted to the ultrasound device 1 during each activation cycle 50. The emission of the activation signal 71 induces the generation of ultrasonic waves allowing the treatment of the patient. The wait and activation cycles 40, 50 are then repeated a plurality of times (150 times in the example illustrated in Figure 4). The table below illustrates how the comparison of two return signals Pri, Pr2 (acquired in response to the emission of two control signals emitted at 5 of the frequencies F1 and F2) with threshold values ​​Si, S2 makes it possible to determine whether the electrical connection between the ultrasonic device 1 and the control unit 2 is correct or not. The electrical connection is considered correct if the first and second conditions (relating to the comparison of the return signals Pri, Pr2 to the 10 threshold values ​​Si, S2) are satisfied in combination: - the first condition on the return signal Pri is satisfied if the measured electrical power is greater than the threshold value Si, - the second condition on the return signal Pr2 is satisfied if the measured electrical power is lower than the threshold value S2. 15 If one and / or the other of the first and second conditions is (are) not satisfied, then the electrical connection between the control unit and the ultrasonic device is faulty. Conditions F2: 0.6 MHz s2= 100 F1: 1.05 MHz Si = 210 1 Connection to the control unit: NO Connection to the implant: NO Pr2=24 Pr2 < S2 => OK Pri = 57 Pri < Si => ALARM 2 Connection to the control unit: YES Connection to the implant: NO Needle tip in insulating medium Pr2=30 Pr2 < S2 => OK Pri = 63 Pri < Si => ALARM 3 Connection to the control unit: YES Connection to the implant: NO Needle tip in conductive medium Pr2 = 107 PR2 > S2 => ALARM Pri = 193 Pri < Si => ALARM 4 Connection to the control unit: YES Connection to the implant: YES Transducer in acoustic contact with conductive medium or tissue Pr2=79 Pr2 < S2 => OK Pri = 257 Pri > Si => OK 5 Connection to the control unit: YES Connection to the implant: YES Transducer in the air, is NOT in acoustic contact with the conductive medium or tissue Pr2=57 Pr2 < S2 => OK Pri = 212 Pri > Si => OK Case No. 5 is representative of a situation in which the electrical connection between the ultrasound device 1 and the control unit 2 is correct, but where the transducer 12 is not in contact with the tissue to be treated. The person skilled in the art 5 will appreciate that the addition of a third condition (associated with the comparison of the return signal Pri with a third threshold value S3 (for example equal to 230) could make it possible to detect this anomaly. The reader will appreciate that the values ​​Pri, Pr2 correspond to raw values ​​obtained from an analog-digital converter. In the above example, these have not been converted into power values, and the thresholds Si, S2 mentioned above correspond to an arbitrary scale of power levels. Of course the values ​​Pr-i, Pr2 could be converted into power values, for example using a quadratic or polynomial function determined by a calibration process of the device according to the invention. 1.2. Second embodiment In a second embodiment, the method uses a vibrational approach. The vibrational approach is based on the fact that the transducer 12 is a resonant element. When such a resonant element is excited by an electrical pulse emitted at a frequency chosen within its working range, it continues to vibrate even after the end of the excitation. Figure 7 illustrates this phenomenon in the case of a transducer 12 excited by an activation signal 81 for an activation duration 83. It can be seen from the signal 82 reflected by the transducer 12 that it continues to vibrate for a non-zero duration 84 after the end of the excitation. This “residual” vibration can be measured using several techniques: - either by directly measuring the voltage sent to the transducer 12, which requires that the voltage signal be digitized at a frequency greater than or equal to twice the excitation frequency (Nyquist limit); this technique requires the integration of a high-speed digitizer in the control unit, - either by measuring the voltage reflected by the transducer 12; this technique requires the integration of a root mean square (RMS) converter or a peak detector to identify peaks in the reflected voltage but eliminates the need for a high-speed digitizer. The return signal signature is unique to the ultrasound device 1 and does not occur when the needle 32 is placed in a conductive material such as saline solution. Referring to Figure 5, the method may comprise the following steps: - During each waiting cycle 40: o emission 413 of a low-power pulse control signal at a frequency F1 chosen from a working frequency range of the transducer 12, o acquisition 423 of a return signal in response, o processing 433 of the return signal to detect a possible connection fault, the processing consisting of extracting the peaks of the return signal after the end of emission of the control signal in order to deduce the state (vibratory or non-vibratory) of the transducer 12, - During each activation cycle 50: o emission 51 of an alarm signal if a connection fault is detected, o emission 52 of an activation signal otherwise, the activation signal consisting of a high power pulsed electrical signal emitted at the frequency F1 of the transducer 12. 2. Control unit With reference to Figure 6, the control unit 2 of an example of an apparatus for implementing the method described above is illustrated. Control unit 2 includes: - an electrical power supply generator 21 for supplying electrical power to the ultrasonic device, - an impedance matching circuit 22 to optimize the transfer of electrical energy between the generator and the ultrasonic device, - a bidirectional coupler 23 between the generator 21 and the impedance matching circuit 22, - a sensor 24 downstream of the coupler to extract an electrical power value from the signals received from the coupler 23, - a controller 25 for processing the signals from the sensor 24 and informing the practitioner of the state of the electrical connection between the ultrasound device 1 and the control unit 2. The bidirectional coupler 23 makes it possible to acquire the return signals. More precisely, the coupler 23 makes it possible to measure the signals reflected by the ultrasonic device 1, and the connection means (cable 31 / needle 32). The bidirectional coupler 23 is for example the model ZFBDC20-61HP+ from the company Mini-Circuits®, used in combination with a low-cost analog-digital converter such as the model Picoscope 3206B from the company Pico-Technology®. Advantageously, the bidirectional coupler 23 is positioned upstream of the impedance matching circuit 22; this makes it possible to simplify the processing of the return signals to extract the reflected electrical power therefrom. The operating principle of the control unit 2 is as follows. During one (or each) waiting cycle 40, the controller 25 commands the generator 21 to emit a low-power control signal. The control signal generated by the generator 21 passes through the bidirectional coupler 23 and the impedance matching circuit 22. It is emitted to the ultrasonic device 1 via the electrical connection means (cable 31 + needle 32). The bidirectional coupler 23 acquires a return signal (or several return signals). More precisely, the bidirectional coupler 23 measures the radiofrequency signal reflected by the intra-body ultrasound device 1, the connection means 31, 32, or the absence of such a radiofrequency signal. The return signal acquired by the bidirectional coupler 23 is transmitted to the sensor 24 which processes it to extract an electrical power value. This electrical power value is transmitted to the controller 25 which compares it to one (or more) threshold value(s) to detect a possible electrical connection fault. If no connection fault is detected, the controller 25 commands the generator 21 to transmit a high-power activation signal at the frequency F1. to induce the generation of ultrasonic waves by the transducer 12 of the ultrasonic device 1. If a connection fault is detected, the controller 25 emits an alert signal in order to warn the practitioner of said fault, for example by emitting an audible and / or visual stimulus on an interface of the control unit 2 (the interface possibly comprising a screen and / or a speaker). Thus, the present invention provides a solution to the problem of detecting connection faults between an implantable ultrasound device and a remote control unit. The reader will understand that numerous modifications can be made to the invention described above without materially departing from the new teachings and advantages described herein. For example, the method according to the invention can be used with other treatment devices than that described in document EP 2 539 021. Also in the foregoing description, the impedance matching circuit has been described as being integrated into the control unit. Alternatively, the impedance matching circuit may be integrated into the ultrasonic device. Therefore, all such modifications are intended to be incorporated within the scope of the appended claims.

Claims

CLAIMS 1. Method for detecting an electrical connection fault between: an ultrasound generating device (1), a remote control unit (2) for delivering electricity to the device (1) and determining and controlling its operating parameters, the control unit (2) being adapted to deliver electricity to the device (1) during at least one activation cycle (50) so as to activate said device (1), each activation cycle (50) being preceded by a waiting cycle (40), the device (1) and the control unit (2) being electrically connected via electrical connection means (31, 32), characterized in that the method comprises a control phase implemented during at least one waiting cycle (40) to detect a fault in the electrical connection between the device (1) and the control unit (2).

2. Method according to claim 1, which comprises the following steps: - During a waiting cycle (40): o The emission (410) by the control unit (2) of at least one control signal at a first instant of the waiting cycle (40), o The acquisition (420) by the control unit (2) of at least one return signal at a second instant of the waiting cycle (40), o Processing (430) the return signal to obtain information on the quality of the electrical connection between the ultrasonic device (1) and the control unit (2), - During an activation cycle (50) subsequent to the waiting cycle (40), the emission (51, 52) of a signal as a function of the information obtained on the quality of the electrical connection, said signal consisting of: o an activation signal if the control unit (2) is correctly connected to the ultrasonic device (1), o an alarm signal if the control unit (2) is not correctly connected to the ultrasonic device (1).

3. Method according to claim 2, in which at least one control signal consists of a low power pulsed electrical signal transmitted at a frequency (F1) chosen from a working frequency range of a transducer (12) of the device (1).

4. Method according to any one of claims 2 or 3, in which the impedance of the device (1) varies as a function of the frequency of the control signal.

5. Method according to any one of claims 2 to 4, in which: - at least one first control signal consists of a pulsed electrical signal emitted at a first frequency (F1) chosen from a working frequency range of a transducer (12) of the device (1), - at least one second control signal consists of a pulsed electrical signal emitted at a second frequency (F2) chosen outside the working frequency range of the transducer (12).

6. Method according to claim 5, which comprises the following steps: During a wait cycle (40): o transmission (411) of a first low-power pulse control signal at a first frequency (F1) chosen from a working frequency range of the transducer (12) of the ultrasonic device (1), and acquisition (421) of a first return signal in response, o transmission (412) of a second low-power pulse control signal at a second frequency (F2) chosen outside the working frequency range of the transducer (12), and acquisition (422) of a second return signal in response, o processing (431) of the first and second return signals to detect a possible connection fault, - During an activation cycle (50) following the waiting cycle (40): o emission (51) of an alarm signal if a connection fault is detected, o emission (52) of an activation signal otherwise, the activation signal consisting of a high power pulsed electrical signal emitted at the working frequency (F1) of the transducer (12).

7. A method according to any one of claims 2 to 6, wherein the processing step comprises a sub-step of comparing the electrical power of each return signal to at least one threshold value.

8. Method according to claim 2, in which the control unit (2) is programmed to: - During a waiting cycle (40): o transmission (413) of a low-power pulse control signal at a frequency (F1) chosen from a working frequency range of the transducer (12), o acquisition (423) of a return signal in response, o processing (433) of the return signal to detect a possible connection fault, the processing consisting of extracting the peaks of the return signal after the end of emission of the control signal in order to deduce therefrom the vibratory or non-vibratory state of the transducer (12), - During an activation cycle (50) following the waiting cycle (40): o emission (51) of an alarm signal if a connection fault is detected, o emission (52) of an activation signal otherwise, the activation signal consisting of a high power pulsed electrical signal emitted at the frequency (F1) of the transducer (12).

9. Apparatus for assisting in the diagnosis and / or treatment of a pathology comprising: an ultrasound generation device (1), a remote control unit (2) for determining and controlling operating parameters of the device (1), and delivering electricity to it during at least one activation cycle (50), each activation cycle (50) being preceded by a waiting cycle (40), electrical connection means (31, 32) between the device (1) and the control unit (2), characterized in that the control unit (2) is programmed to implement the steps of the method according to any one of claims 1 to 8. Tl 10. Apparatus according to claim 9, wherein the control unit (2) comprises a directional coupler (23) for acquiring the return signals, said directional coupler being connected upstream of an impedance matching circuit (22).

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