JP2018011746A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically optimize a DC level (offset) and gain in a biological signal processing circuit of an ultrasonic diagnostic apparatus.SOLUTION: A biological signal processing circuit 40 is a circuit for processing a biological signal such as an electrocardiographic signal. The circuit includes a level adjustment circuit 42, an amplification circuit 44, a conversion circuit (ADC) 46, and the like. The operation of the level adjustment circuit 42 is subjected to feedback control, and a DC level of an analog signal 54 input in the amplification circuit 44 is automatically adapted to an input reference level of the amplification circuit. Then, the gain of the amplification circuit 44 is adjusted so that a synchronization signal 62 is appropriately generated. Adjustment may be made based on the biological signal measured of a healthy person, or adjustment is made based on the biological signal generated by a dummy signal.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to adjustment of a biological signal processing circuit.

  An ultrasonic diagnostic apparatus is a medical apparatus that forms an ultrasonic image based on a reception signal obtained by transmitting / receiving ultrasonic waves to / from a living body. For example, in cardiac ultrasound diagnosis, an electrocardiogram signal is sent from an electrocardiogram monitor (electrocardiograph) to an ultrasound diagnostic apparatus. An electrocardiographic signal is displayed as a waveform along with a tomographic image of the heart on the display of the ultrasonic diagnostic apparatus. A biological signal other than the electrocardiogram signal, such as a pulse wave signal or a heart sound signal, may be measured.

  In general, an ultrasonic diagnostic apparatus is provided with an input port for receiving a biological signal, and a biological signal input through the input port is sent to a host controller through a biological signal processing circuit. The biological signal processing circuit usually includes an amplification circuit that amplifies an analog signal as a biological signal, a level adjustment circuit (offset adjustment circuit) that adjusts a DC level (offset) of the analog signal input to the amplification circuit, and an amplification circuit. A conversion circuit for converting the analog signal into a digital signal. The digital signal is sent to the host controller.

  The level adjustment circuit is for adjusting the DC level (offset) of the analog signal input thereto with the input reference level of the amplifier circuit (generally a level at which the amplification factor becomes zero). If the DC level is deviated from the input reference level, the DC level of the biological signal moves when the gain in the amplifier circuit is varied. As a result, the waveform of the biological signal moves up and down on the screen. End up. If the DC level of the input signal matches the input reference level, such a problem does not occur. In the conventional ultrasonic diagnostic apparatus, when an electrocardiogram monitor is connected, the offset adjustment is manually performed while observing the biological signal waveform displayed on the screen, and then the gain is adjusted. After such adjustment, an ultrasound diagnosis was performed.

  Patent Document 1 describes an ultrasonic diagnostic apparatus that displays an electrocardiographic waveform together with an ultrasonic image. When the electrocardiogram waveform is displayed, the amplitude is automatically adjusted. Patent Document 2 also describes an ultrasonic diagnostic apparatus that automatically adjusts the amplitude of an electrocardiographic waveform. However, Patent Documents 1 and 2 do not describe automatic adjustment of the DC level.

  Patent Document 3 describes an optical disk reproducing apparatus. The apparatus includes a circuit that automatically adjusts the level of the optical pickup signal and a circuit that automatically adjusts the gain of the optical pickup signal after the level adjustment. The optical pickup signal is not a signal displayed as a waveform on the screen. In the first place, the optical pickup signal is greatly different from the biological signal in terms of signal characteristics.

JP 2000-210228 A JP 2001-104306 A JP 2005-92999 A

  In order to display a biological signal together with an ultrasonic image in an ultrasonic diagnostic apparatus, it is necessary to adjust (offset adjustment) the DC level of the input signal prior to that. Is a heavy burden. According to manual adjustment, there is a problem that adjustment results suitable for various situations cannot always be obtained. A similar problem can be pointed out in the adjustment of gain or amplification.

  An object of the present invention is to reduce or eliminate a user's burden in adjustment of a biological signal processing circuit. Alternatively, an object of the present invention is to naturally optimize the DC level of the biological signal and the amplitude of the biological signal. Alternatively, the biological signal processing circuit can be easily adjusted.

  An ultrasonic diagnostic apparatus according to the present invention is provided between an input port to which a biological signal measuring device is connected, an amplification circuit that amplifies an analog signal from the input port, and the input port and the amplification circuit. A level adjustment circuit that adjusts a DC level of an analog signal input to the amplifier circuit; a conversion circuit that converts the analog signal output from the amplifier circuit into a digital signal; and when the adjustment mode is executed, based on the digital signal And a control circuit for adjusting the DC level of the analog signal after level adjustment to the input reference level of the amplifier circuit by controlling the operation of the level adjustment circuit.

  According to the above configuration, the control circuit feedback-controls the DC level (offset) of the analog signal input to the amplifier circuit based on the digital signal. Specifically, the DC level of the analog signal input to the amplifier circuit is adapted to the input reference level in the amplifier circuit. The input reference level is desirably a level at which the gain (amplification factor) becomes zero. Since the digital signal sent to the host controller is referenced, accurate adjustment can be performed. The polarity of the biological signal may be determined and controlled accordingly.

  Preferably, the control circuit obtains a representative amplitude value from one or a plurality of waveform flat sections in the digital signal, and controls the operation of the level adjustment circuit based on the representative amplitude value. Since the DC level can be regarded as a level within the waveform flat section, a representative amplitude value (for example, an average value) is obtained from the waveform flat portion. One sampling may be performed for each waveform flat section, or a plurality of samplings may be performed.

  Preferably, the control circuit adjusts the gain of the amplifier circuit after adjusting the DC level to the input reference level. Thereby, gain adjustment can be performed correctly.

  Preferably, the conversion circuit is a first conversion circuit that converts an analog signal output from the amplification circuit into a first digital signal, and the ultrasonic diagnostic apparatus further includes the analog signal output from the amplification circuit. An extraction circuit for extracting a signal component for generating a synchronization signal from the signal, a second conversion circuit for converting the signal component for generating the synchronization signal into a second digital signal, and comparing a peak value indicated by the second digital signal with a threshold value A synchronization signal generating circuit that generates a synchronization signal by performing the adjustment mode, and the control circuit is configured to gain in the amplifier circuit so that a peak value indicated by the second digital signal exceeds the threshold value when the adjustment mode is executed. Adjust.

  According to the above configuration, the DC level is adjusted based on the first digital signal output from the first conversion circuit, and the gain is adjusted based on the second digital signal output from the second conversion circuit. Each peak value constituting the second digital signal is compared with a threshold value, thereby generating a synchronization signal. The gain is adjusted to reach a target value higher than the threshold value so that the peak value exceeds the threshold value. Thereby, a synchronizing signal can be generated appropriately.

  Preferably, the adjustment mode is executed in a state in which a signal source for supplying a dummy signal to the biological signal measuring device is provided and the dummy signal is supplied to the biological signal measuring device. When a biological signal is acquired from a living body for adjustment of the biological signal processing circuit, problems such as giving a burden to the person arise. If a signal source is used, such a burden does not occur. After execution of the adjustment mode, electrodes and the like are actually installed on the subject, and a biological signal is acquired.

  A set value set of level and gain may be stored for each biological signal measuring device, and when any of the biological signal measuring devices is connected, the corresponding set of set values may be read and set.

  ADVANTAGE OF THE INVENTION According to this invention, a user's burden can be reduced or eliminated in adjustment of a biological signal processing circuit. Alternatively, the DC level and amplitude of the biological signal are naturally optimized. Alternatively, the biological signal processing circuit can be easily adjusted.

1 is a block diagram showing a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention. It is a figure which shows the 1st structural example of a biological signal processing circuit. It is a figure for demonstrating level adjustment and gain adjustment. It is a figure for demonstrating the calculation method of DC level average value. It is a figure for demonstrating the calculation method of a peak average value. It is a flowchart which shows the operation example of a circuit adjustment part. It is a block diagram which shows the ultrasonic diagnosing device which concerns on other embodiment. It is a figure for demonstrating adjustment by a dummy signal. It is a figure which shows the 2nd structural example of a biological signal processing circuit.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention. An ultrasonic diagnostic apparatus is a medical apparatus installed in a medical institution or the like.

  In FIG. 1, the ultrasonic diagnostic apparatus includes an apparatus main body 10 and a probe 12. The probe 12 has a 1D array transducer, thereby forming an ultrasonic beam. The ultrasonic beam is electronically scanned. As an electronic scanning method, an electronic linear scanning method, an electronic sector scanning method, and the like are known. A 2D array transducer may be provided instead of the 1D array vibration. The apparatus main body 10 is provided with a main body side connector 16 to which a probe side connector is connected.

  The apparatus body 10 is provided with an input terminal (input port) 38 for receiving a biological signal. In the illustrated example, an electrocardiographic monitor 37 is connected to the input terminal 38 as one of the biological signal measuring devices. It is a device that generates an electrocardiographic signal from a voltage induced between a plurality of electrodes attached to the subject 14.

  The configuration of the apparatus main body 10 will be described. The transmission / reception unit 18 is an electronic circuit that functions as a transmission beam former and a reception beam former. At the time of transmission, a plurality of transmission signals are supplied in parallel from the transmission / reception unit 18 to the array transducer. As a result, a transmission beam is formed by the action of the array transducer. At the time of reception, when a reflected wave from the living body is received by the array transducer, a plurality of received signals are output from the array transducer to the transmission / reception unit 18 in parallel. The transmission / reception unit 18 performs phasing addition of a plurality of reception signals, thereby generating beam data corresponding to the reception beam.

  The beam data processing unit 20 has a known circuit configuration such as a detection circuit and a logarithmic conversion circuit, and sequentially processes input beam data. The image forming unit 22 generates display frame data by coordinate conversion, interpolation processing, and the like based on a plurality of beam data (received frame data) arranged in the electronic scanning direction. The display frame data constitutes a tomographic image. The image data is sent to the display device 26 via the display processing unit 24, and a tomographic image is displayed on the display device 26. Other ultrasound images may be displayed. The display 26 is configured by an LCD, an organic EL device, or the like.

  The biological signal processing circuit 40 is a circuit that processes an analog signal (biological signal) input from the input terminal 38. Specifically, the biological signal processing circuit 40 is a circuit that amplifies the analog signal and converts it into a digital signal. Prior to amplification, the DC level of the analog signal is adjusted. The biological signal processing circuit 40 has two processing systems in the present embodiment, and thereby, a first digital signal representing a biological signal waveform and a second digital signal representing an extracted R wave component are included. Has been generated. Those signals are output to the host controller 30.

  The host controller 30 includes a CPU and an operation program. The host controller 30 controls the operation of each component in the apparatus main body 10. In addition, the host controller 30 processes two digital signals output from the biological signal processing circuit 40. During execution of the adjustment mode, the host controller 30 performs feedback adjustment of the operation of the biological signal processing circuit 40.

  This will be specifically described. The host controller 30 generates a waveform image to be combined with the ultrasonic image so that the waveform of the biological signal is displayed on the screen of the display device 26 based on the first digital signal. The host controller 30 also generates an R wave synchronization signal based on the second digital signal (R wave extraction signal). The function is represented as a synchronization signal generator 34. The R wave synchronization signal is used when an operation synchronized with the heartbeat is performed.

  In the present embodiment, the host controller 30 adjusts the biological signal processing circuit 40 when executing the adjustment mode. This function is expressed as a circuit adjustment unit 32. The circuit adjustment unit 32 has a level (offset) automatic adjustment function and a gain (amplification factor) automatic adjustment function. The circuit adjustment unit 32 includes a storage unit 36 that stores a set value set after adjustment. The storage unit 36 may be provided outside the host controller 30.

  When the adjustment mode is executed, a biological signal obtained from the subject (subject) 14 may be used. However, since the biological signal may be abnormal, it is healthy instead of the subject. It is desirable to optimize the operation of the biological signal processing circuit 40 based on a biological signal obtained from a healthy person with a person as a measurement target. If the adjustment is completed in advance for each biological signal measuring device and the result is stored, the operation of the biological signal processing circuit 40 can be quickly optimized by using the corresponding result when the biological signal measuring device is connected. . That is, in the storage unit 36, for each biological signal measuring device, a set value set consisting of a set value when an optimum level is obtained and a set value when an optimum gain is obtained is stored. When the biological signal measuring device is connected, the type may be recognized, a set of set values corresponding to the type may be read, and these may be actually set. A signal source that changes to the subject 14 may be provided in the apparatus main body 10 or outside. This will be described later with reference to FIG.

  FIG. 2 shows a first configuration example of the biological signal processing circuit 40. An analog signal 52 is input to the level adjustment circuit 42. It is a biological signal, which in this embodiment is an electrocardiogram signal from an electrocardiogram monitor. The level adjustment circuit 42 functions as a level shifter for adjusting the DC level (offset level) of the analog signal 54 input to the subsequent amplification circuit 44 to the amplification factor zero level at the input of the amplification circuit 44. When the adjustment mode is executed, a level control signal 64 is output from the host controller, and the value of the potentiometer (digital potentiometer) 42a in the level adjustment circuit 42 is variably set by the level control signal 64. As a result, the DC level is manipulated.

  The amplifier circuit 44 is a circuit that amplifies the input analog signal 54. Amplification is performed for both positive and negative polarities. If the DC level of the analog signal 54 matches the zero gain level (input reference level) on the input side, the amplified analog output from the amplifier circuit 44 is output even if the gain, that is, the gain is variable. The DC level in the signal does not move up or down. The amplification factor zero level is set to the intermediate level of the input side entrance of the ADC 46 in the subsequent stage. The amplification circuit 44 includes a potentiometer (digital potentiometer) 44a. When the adjustment mode is executed, gain adjustment is executed after level adjustment. In the gain adjustment process, an amplification control signal 66 is output from the host controller. The value of the potentiometer 44a is variably set by the amplification control signal 66. In the present embodiment, the amplification factor is determined so that the amplitude of the R wave extraction signal 62 that is the second digital signal is appropriate.

  The ADC 46 is a conversion circuit that converts the analog signal 56 into the first digital signal 60. The level adjustment and the gain adjustment are performed as described above so that the DC level and gain of the analog signal input thereto are appropriate for the front end of the ADC 46.

  The BPF (band pass filter) 48 is a filter that extracts an R wave component in the electrocardiogram signal. The extracted component is sent to the ADC 50 and converted into an R-wave extraction signal 62 as a second digital signal. Based on the R-wave extraction signal 62, the host controller generates an R-wave synchronization signal.

  In the present embodiment, the digital signal 60 as the first digital signal is referred to at the time of level adjustment, and the R wave extraction signal 62 as the second digital signal is referred to at the time of gain adjustment. Note that the R wave synchronization signal may be directly generated based on the digital signal 46 without the BPF 48 and the ADC 50. A DAC may be provided instead of each of the potentiometers 42a and 44a. Adjustments may be made with other configurations.

  FIG. 3 shows an electrocardiogram signal 68 before adjustment and an electrocardiogram signal 74 after adjustment. The horizontal axis is the time axis, and the vertical axis indicates the voltage on the input side of the amplifier circuit. Here, the voltage range 76 is between 0 and 3.3V, and its intermediate level is 1.65V. The intermediate level is a reference level 75 with an amplification factor of zero.

  In the adjustment mode, first, level adjustment indicated by reference numeral 70 is performed on the electrocardiogram signal 68 before adjustment. That is, the DC level of the electrocardiogram signal 68 is adjusted to the reference level 75. As a result, the DC level does not change even if the gain is changed. Subsequently, the gain is adjusted, and the amplitude of the electrocardiogram signal is optimized as indicated by reference numeral 72. Specifically, the gain is adjusted so that the peak value in the R wave extraction signal exceeds the threshold value, and more specifically, the peak value reaches the target value above the threshold value. As a result of the adjustment, an electrocardiogram signal 74 is obtained. After the adjustment is completed, an ultrasonic diagnosis (inspection mode) is performed.

  FIG. 4 shows an example of the level adjustment method. This process is executed by the host controller. A time window having a predetermined time T1 (for example, 1.5 sec) is sequentially set for the electrocardiogram waveform (first digital signal) 68 before the adjustment is completed, and a plurality of sections 78 are set in each time window. . The time length of each section 78 is ΔT (for example, 100 msec). In each section 78, it is determined whether or not the fluctuation width of the waveform falls within a predetermined amplitude width (for example, ± 0.1 mV). Reference numeral 80 indicates a determination result for each section 78. OK or NG determination is made for each section. A DC level average value 82 is calculated as a representative value to be referred to in feedback control based on one or a plurality of sections in which OK is determined. For example, the voltage at one or a plurality of points is sampled for each section in which OK is determined, and the DC level average value 82 is calculated based on them.

  According to the above method, it is possible to specify the DC level based only on the portion where flatness is recognized, that is, ignoring the waveform change portion. Other methods (for example, a smoothing method and a filter method) may be used. Since the polarity of the biological signal may be reversed, it is desirable to adopt a method that can cope with such a case.

  FIG. 5 shows an example of the gain adjustment method. This process is also executed by the host controller. The R wave extraction signal (second digital signal) 84 after the level adjustment has a plurality of peaks (or peak rows) 86 corresponding to the R wave. The horizontal axis is the time axis, and the vertical axis indicates the digital peak value (absolute value). A time window having a certain time (for example, 1.5 sec) is sequentially set for the R wave extraction signal 84. Within each time window, peak values (absolute values) of a plurality of peaks are referred to, and a peak average value 94 is calculated based on them. The gain is adjusted so that the peak average value 94 reaches the target value 90 that is higher than the threshold value 88, or so as to match (see reference numeral 92).

  Of course, the above method is an example, and as a result, as long as the amplitude of the waveform can be optimized, other methods can be used. In the present embodiment, gain adjustment is performed based on the second digital signal that is the R-wave extraction signal, but gain adjustment can also be performed based on the first digital signal.

  FIG. 6 is a flowchart showing an example of the operation of the host controller in the adjustment mode. In S10, an average value (current DC level) of the flat portion in the first digital signal is calculated. In S12, it is determined whether or not the average value is within an allowable range as viewed from the reference level. If it is out of the allowable range, the level is changed by one step in S14, and the processes after S10 are executed. If it is determined in S12 that the value is within the allowable range, a peak value (average value) is calculated based on the second digital signal in S16. In S20, whether or not the peak value is within the allowable range with reference to the target value. Is judged. If it is outside the allowable range, the gain is changed by one step in S18, and the processes after S16 are repeatedly executed. In S20, if the peak value is within the allowable range, this process is terminated.

  FIG. 7 shows a second configuration example of the ultrasonic diagnostic apparatus. The same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted. In the second configuration example shown in FIG. 7, a pulse signal generator (signal source) 96 is provided in the apparatus main body 10. The plurality of electrodes of the electrocardiogram monitor 37 are not attached to the subject 14, and weak dummy (simulated) signals from the pulse signal generator 96 are given to the plurality of electrodes. The pseudo electrocardiogram signal output from the electrocardiogram monitor is given to the biological signal processing circuit 40, and its operation is adjusted. It is desirable to generate the pulse signal so that the pseudo ECG signal is as close as possible to the ECG signal of a healthy person. The peak value of the pulse simulating the R wave is, for example, several mV.

  FIG. 8 shows a pseudo electrocardiogram signal 98 before adjustment and a pseudo electrocardiogram signal 104 after adjustment. The horizontal axis is the time axis, and the vertical axis indicates the voltage of the signal input to the amplifier circuit. The pseudo electrocardiogram signal 98 has a plurality of pulses 100 and 102 simulating R waves. As indicated at 106, the DC level is first optimized and then the gain is optimized. Since the pulse form and generation time are known, sampling may be performed using the pulse form and generation time. For example, if the pulses 100 and 102 are generated with a period of 50 msec and the pulse width of each of the pulses 100 and 102 is 20 msec, the start timing is 20 msec after the rising point of each pulse 100 and 1102, and the next pulse is generated from there. A plurality of voltages may be sampled in the period immediately before the rise, and the DC level average value may be calculated based on these voltages. In the calculation of the peak average value, the sampling time may be determined by using the fact that the pulse generation time is known.

  FIG. 9 shows a second configuration example of the biological signal processing circuit. The same components as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. In the second configuration example shown in FIG. 9, the BPF 48 and the ADC 50 shown in FIG. 2 are not included. Otherwise, the configuration is the same as that shown in FIG. That is, this second configuration example does not perform R wave component extraction. Instead, an R wave synchronization signal is generated based on the digital signal 60 in the host controller. Since such a configuration is simple, advantages such as cost reduction can be obtained.

  In the above embodiment, the processing for the electrocardiogram signal has been described exclusively, but other biological signals may be processed. Examples of such signals include heart sound signals and pulse wave signals. If a biological signal includes a component representing a heartbeat, a synchronization signal corresponding to the R-wave synchronization signal can be generated therefrom. Even when such a component is not included (for example, a respiratory signal), the burden on the user can be reduced by automating at least the former, preferably both of the level adjustment and gain adjustment.

DESCRIPTION OF SYMBOLS 10 Apparatus main body, 12 Probe, 14 Subject, 30 Host controller, 32 Circuit adjustment part, 37 ECG monitor, 40 Biological signal processing circuit, 42 Level adjustment circuit (offset adjustment circuit), 44 Amplification circuit, 46, 50 ADC ( Analog-digital converter).

Claims (5)

An input port to which a biological signal measuring device is connected;
An amplifier circuit for amplifying an analog signal from the input port;
A level adjustment circuit that is provided between the input port and the amplifier circuit and adjusts a DC level of an analog signal input to the amplifier circuit;
A conversion circuit for converting an analog signal output from the amplifier circuit into a digital signal;
A control circuit for adjusting the DC level of the analog signal after the level adjustment to the input reference level of the amplifier circuit by controlling the operation of the level adjustment circuit based on the digital signal at the time of executing the adjustment mode;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
The control circuit obtains a representative amplitude value from one or a plurality of waveform flat sections in the digital signal, and controls the operation of the level adjustment circuit based on the representative amplitude value.
An ultrasonic diagnostic apparatus. The apparatus of claim 1.
The control circuit adjusts the gain of the amplifier circuit after adjusting the DC level to the input reference level.
An ultrasonic diagnostic apparatus. The apparatus of claim 3.
The conversion circuit is a first conversion circuit that converts an analog signal output from the amplifier circuit into a first digital signal;
The ultrasonic diagnostic apparatus further includes:
An extraction circuit that extracts a signal component for generating a synchronization signal from the analog signal output from the amplification circuit;
A second conversion circuit for converting the signal component for generating the synchronization signal into a second digital signal;
A synchronization signal generating circuit that generates a synchronization signal by comparing a peak value indicated by the second digital signal with a threshold;
Including
The control circuit adjusts a gain in the amplifier circuit so that a peak value indicated by the second digital signal exceeds the threshold value when the adjustment mode is executed.
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
A signal source for providing a dummy signal to the biological signal measuring device;
The adjustment mode is executed in a state where the dummy signal is given to the biological signal measuring device.
An ultrasonic diagnostic apparatus.

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