JP2009261441A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively remove electromagnetic noise from another apparatus such as an electrocautery from reception signals in ultrasonic diagnosing. <P>SOLUTION: A probe 10 is provided with a dummy signal line 14 and a capacitor 18 as a dummy vibration element. A noise cancellation control part 44 generates gate signals 102 indicating an electromagnetic noise generation period on the basis of cardiographic signals 100. Noise cancellation processing is performed in the noise generation period indicated by the gate signals 102. To put it concretely, signals from the dummy signal line 14 are utilized as cancellation signals 106 and the cancellation signals 106 are subtracted from reception signals in respective differential amplifiers 26. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to cancellation processing of electromagnetic noise caused by an electric knife or the like.

  Electromagnetic noise from external equipment may be mixed during ultrasonic diagnosis. For example, when performing an ultrasonic diagnosis of the heart from the esophagus using a transesophageal probe during surgery, it is known that a large electromagnetic noise is mixed in an ultrasonic image when an electric knife is used. Such electromagnetic noise is considered to be mainly mixed from the distal end portion of the eclipse probe, and is also considered to be mixed from a plurality of signal lines in the insertion tube connected to the distal end portion. Furthermore, electromagnetic noise may enter in other portions.

  When such electromagnetic noise enters a plurality of reception signals from a plurality of vibration elements, it causes a noticeable stripe pattern or the like on the ultrasonic image. An example is shown in FIG. 4, and image noise 72 appears on the tomographic image 70. The appearance of image noise on the ultrasonic image depends on the form and cycle of the drive signal supplied to the electric knife. In the erosion probe, since the entire insertion tube including the distal end portion is reduced in diameter, the shielding effect against electromagnetic noise tends to decrease. For this reason, it is more susceptible to electromagnetic noise than when performing ultrasonic diagnosis using a normal body surface probe. In addition, since various devices (surgical devices and diagnostic devices) are installed in the operating field, large electromagnetic noise is likely to occur.

JP-A-6-63044 JP-A-2-286142

  The electromagnetic noise as described above greatly deteriorates the image quality of the ultrasonic image and becomes a major obstacle in observing the ultrasonic image. Therefore, it is desired that electromagnetic noise does not appear on the ultrasonic image or does not stand out even if it appears. By the way, the above-mentioned electromagnetic noise problem becomes prominent during surgery, especially when using an electric knife. Of course, it can also occur when a probe other than an intracavity probe is used. It is a problem. Patent Document 1 describes that electromagnetic noise is observed with a dummy vibrator and a dummy cable, and the noise mixed in the received signal is canceled using the observed electromagnetic noise. However, if the process is always performed, there is a risk that the image quality is deteriorated at a portion other than the noise generation site. The same problem can be pointed out in Patent Document 2.

  An object of the present invention is to locally process electromagnetic noise that has entered from an external device so that an image portion other than a portion where an image noise is generated does not deteriorate more than necessary.

  The present invention is obtained by transmitting and receiving ultrasonic waves in a gate signal generating means for generating a gate signal based on a first reference signal including electromagnetic noise generated in an external device, and in a noise cancellation period based on the gate signal. Noise cancellation means for performing noise cancellation processing on the received signal using a second reference signal that is the same as or different from the first reference signal and includes electromagnetic noise generated in the external device; The present invention relates to an ultrasonic diagnostic apparatus.

  According to the above configuration, the gate signal is generated based on the first reference signal. The gate signal represents a noise generation period. A noise generation period may be specified as a period including all of the electromagnetic noise on the time axis, or a noise generation period may be specified as a period including the main part of the electromagnetic noise. A noise cancellation period is determined based on such a gate signal. The noise cancellation period may be the same as the above-described noise generation period, or may be determined separately based on the noise generation period. In any case, it is desirable not to continue the noise canceling operation at all times, but to specify the period in which the electromagnetic noise is generated and to locally perform the noise canceling process accordingly. The noise canceling means performs noise cancellation processing based on the second reference signal representing electromagnetic noise on the received signal, and subtracts the second reference signal from the received signal, for example. As described above, the noise cancellation period is determined according to the gate signal, and the noise cancellation process is executed only within the period, so that it is possible to eliminate or reduce the deterioration of the image quality at the part other than the noise occurrence part. For example, electromagnetic noise from the electric knife causes a unique striped pattern in the ultrasonic image, and it is possible to adaptively perform noise cancellation processing according to the appearance of such a striped pattern.

  Preferably, the probe includes an intracorporeal probe having an insertion tube to be inserted into a body cavity with an ultrasonic transducer, and the insertion tube transmits the electromagnetic noise without transmitting an electrical signal for transmission and reception. The second reference signal is a signal transmitted from the electromagnetic noise transmission signal line. According to this configuration, it is possible to separately measure the same electromagnetic noise mixed in the received signal and cancel the electromagnetic noise using the same.

  Preferably, the gate signal generation means generates the gate signal by determining that the amplitude of the electrocardiogram signal has continuously exceeded a predetermined threshold. According to this configuration, a gate signal can be generated based on an electrocardiogram signal. In this case, since a continuity condition is added, an R wave included in the electrocardiogram signal is mistaken as electromagnetic noise. Can prevent problems.

  Preferably, both the first reference signal and the second reference signal are electrocardiogram signals, the gate signal is generated based on the electrocardiogram signals, and the noise cancellation processing is executed. According to this configuration, electromagnetic noise can be easily canceled using an existing electrocardiogram signal without separately providing a dummy signal line.

  The present invention relates to a gate signal generating means for generating a gate signal based on an electrocardiogram signal including electromagnetic noise from an electric knife used during surgery, and transmission and reception of ultrasonic waves in a noise cancellation period based on the gate signal. Noise canceling means for performing noise cancellation processing on the plurality of reception signals obtained by waves using a dummy reception signal including electromagnetic noise from the external device, and the noise cancellation processing are individually performed. And an adding means for adding a plurality of received signals and outputting beam data.

  In ultrasonic diagnosis during surgery, electromagnetic noise from an electric scalpel is likely to be mixed in ultrasonic diagnosis using an intracorporeal probe, particularly a transesophageal probe, which causes annoying image noise on the ultrasonic image. Let According to the above configuration, such image noise can be effectively reduced, so that ultrasonic diagnosis during surgery can be performed appropriately.

  As described above, according to the present invention, it is possible to effectively reduce image noise caused by electromagnetic noise and improve the image quality of an ultrasonic image.

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

  FIG. 1 is a block diagram showing the main configuration of an ultrasonic diagnostic apparatus according to the present invention. This ultrasonic diagnostic apparatus is an apparatus that has a transesophageal probe and performs ultrasonic diagnosis on the heart by transmitting and receiving ultrasonic waves in the esophagus. Of course, the present invention can be applied to other types of ultrasonic diagnostic apparatuses.

  The probe 10 is the above-mentioned eclipse probe, and a plurality of signal lines 12 and 14 are provided in the insertion tube. Each signal line 12 shown in the figure is an original signal line for transmitting a transmission signal and a reception signal, and the signal line 14 is a dummy signal line for transmitting electromagnetic noise. A probe head is provided at the tip of the insertion tube, and a 1D array transducer is provided in the probe head. The 1D array transducer includes a plurality of vibrating elements 16. An ultrasonic beam is formed by the 1D array transducer, and the ultrasonic beam is electronically scanned. As an electronic scanning method, electronic sector scanning or the like is known.

  A signal line 12 is connected to each of the plurality of vibration elements 16. On the other hand, a capacitor 18 that is electrically equivalent to the vibration element 16 (having similar electrical impedance) is connected to the tip of the dummy signal line 14. The capacitor 18 functions as a sensor that receives electromagnetic noise from an external device, particularly an electric knife, within the probe head. Similarly, the dummy signal line 14 also functions as a sensor that receives electromagnetic noise. In the present embodiment, electromagnetic noise from the outside is observed inside the body by the capacitor 18 and the dummy signal line 14 which are dummy vibration elements in this way. However, as will be described later, it is also possible to perform noise cancellation processing using electromagnetic noise included in the electrocardiogram signal.

  Each of the plurality of transmitters 22 is a waveform generator, and a transmission signal output therefrom is sent to the corresponding signal line 12 via the amplifier 24 and further via the switch 20. Each amplifier 24 is a transmission amplifier, which performs power amplification. Each switch 20 is a circuit that connects the signal line 12 to the transmitter during transmission and connects the signal line 12 to the receiver during reception. The plurality of transmitters 22 and the plurality of transmission amplifiers 24 constitute a transmission beam former as a whole.

  On the other hand, the configuration of the reception beamformer will be described. The reception signal from each signal line 12 is sent to the corresponding A / D converter 30 via each switch 20 and each differential amplifier 26. . A memory or the like (not shown) is provided at the subsequent stage of each A / D converter 30, and a plurality of received signals read from the memory are added by the adder 32. That is, a reception beam is formed by such a phasing addition process, and a reception signal after phasing addition as beam data is output from the adder 32.

  In the present embodiment, a differential amplifier 26 is provided for each channel, that is, for each signal line 12 as illustrated. This differential amplifier 26 performs noise cancellation processing, and removes noise components contained in the received signal using a cancellation signal 106 generated within a specific cancellation period, as will be described below. It is. Specifically, the cancel signal 106 is composed of electromagnetic noise itself, and the electromagnetic noise included in the received signal is canceled by the cancel signal 106.

  The electrocardiogram signal 100 output from the electrocardiograph 46 is sent to an image processing unit (not shown) in order to display an electrocardiogram waveform together with the ultrasonic image, and the electrocardiogram signal 100 is sent to a noise cancellation control unit. 44. A specific configuration example of the noise cancellation control unit 44 will be described later with reference to FIG. 2. The noise cancellation control unit 44 specifies the period of electromagnetic noise included in the electrocardiogram signal 100 to thereby determine the noise generation period. A representative gate signal 102 is generated. The gate signal 102 is supplied to the switch unit 33.

  The switch unit 33 includes two switch circuits 34 and 36 and an amplifier 42 as shown in the figure. The amplifier 42 is a circuit for performing impedance conversion. The switch circuits 34 and 36 are turned on when the gate signal 102 represents a noise generation period, and connect the reception signal 104 output from the dummy signal line 14 to the input side of the amplifier 42. As a result, the received signal 104 is sent to each differential amplifier 26 as a cancel signal 106. On the other hand, when the gate signal 102 represents outside the noise generation period, the switch circuits 34 and 36 connect the signal line 104 and the input side of the amplifier 42 to the ground so that the noise canceling process is not performed. That is, the cancel signal 106 is not substantially output, thereby effectively preventing the problem that the received signal is canceled unnecessarily outside the site where the noise occurs. That is, in this embodiment, in order to solve the problem caused by always performing the noise canceling process, a gate signal representing the noise generation period is generated based on the reference signal, and the local signal is generated only within the noise generation period. Noise cancellation processing is performed.

  FIG. 2 shows a specific configuration example of the noise cancellation control unit 44 shown in FIG. The noise cancellation control unit 44 functions as a gate signal generation unit. The electrocardiogram signal 100 output from the electrocardiograph 46 passes through a low-pass filter (LPF) 50, and is further amplified by an amplifier 52 and then input to an A / D converter 54. As a result, an electrocardiogram signal as digital data is obtained. The digital data is output to an image display unit (not shown). On the other hand, the electrocardiogram signal 100 is input to a high pass filter (HPF) 56. The HPF 56 is a circuit that allows only a high-frequency component contained in the electrocardiogram signal to pass therethrough, and only the component centered on electromagnetic noise is output from the HPF 56. The component includes an R wave. The comparator 58 compares the signal output from the HPF 56 with a predetermined threshold signal, and generates an output pulse when the amplitude of the electrocardiogram signal is larger than the predetermined threshold signal. Here, the predetermined threshold signal represents the threshold α, that is, threshold processing for specifying electromagnetic noise in the amplitude axis direction is performed. The counter 60 operates in synchronization with a predetermined clock, and counts pulses input to its input terminal. However, it is periodically reset by a reset signal synchronized with the transmission trigger. The output of the counter 60 is given to a comparator 62, which outputs a HI signal when a count value larger than a predetermined value n is input. That is the gate signal 102 described above.

  The operation of the circuit shown in FIG. 2 will be described with reference to FIG. (A) shows an electrocardiogram signal. This electrocardiographic signal includes an R wave 100B. Furthermore, 100 A of electromagnetic noise resulting from the drive of the electric knife is included. The comparator 58 shown in FIG. 2 outputs a pulse when an amplitude exceeding the threshold value α is observed. The output pulse is represented by (B). (C) shows a clock input to the counter 60, and (D) shows a reset pulse having a transmission repetition period. Further, (E) shows the output of the counter. When the pulse shown in (B) is input, the number of the pulses is counted in the counter, but the value of the counter is cleared by the input of the reset pulse shown in (D). The output of the counter is shown in (F). As described above, the comparator 62 outputs an HI signal when a count value equal to or greater than n is obtained, where n is 2, for example. That is, as shown in (E), the gate signal 102 does not change when the counter output is 0 or 1, while the gate signal 102 is in the HI state when the counter output is 2 or more. It becomes. The HI state represents a noise generation period.

  According to such a circuit configuration, it is possible to prevent a problem that an R wave is erroneously recognized as electromagnetic noise, thereby causing an unnecessary noise canceling operation. On the other hand, the initial several μs of the actual generation period of electromagnetic noise will be recognized as being outside the noise generation period, but such a period is a very short period, so that period. If it is within the range, noise components appear in the image with little problem. Of course, if the circuit configuration that separates the R wave and the electromagnetic noise with higher accuracy and identifies only the electromagnetic noise is adopted, it is possible to completely cancel the entire electromagnetic noise.

  In the present embodiment, the gate signal is generated by combining the threshold condition in the amplitude axis direction and the time condition in the time axis direction in the electrocardiogram signal, but other conditions are adopted instead of these conditions. In addition, other conditions may be added together with these conditions. For example, if the R wave and the electromagnetic noise are significantly different on the frequency axis, only the electromagnetic noise component is extracted using a band pass filter or the like, and the generation period is specified to generate a gate signal. You may do it.

  In the above-described embodiment, an electrocardiogram signal is used as the first reference signal and a reception signal from the dummy signal line is used as the second reference signal. However, only the electrocardiogram signal is used as the first reference signal and the second reference signal. It may be used as a reference signal to generate a gate signal and a cancel signal. That is, as shown in FIG. 3A, if electromagnetic noise appears significantly in the electrocardiogram signal, the electromagnetic noise is specified on the electrocardiogram signal, and the gate signal is generated based on the specified electromagnetic noise. Alternatively, the electromagnetic noise may be used as a cancel signal, and processing for canceling the electromagnetic noise included in each received signal may be performed. In the above-described embodiment, the noise cancellation processing is individually performed on a plurality of reception signals, and the reception signals are subjected to the phasing addition processing. Therefore, there is an advantage that a noise reduction effect can be further achieved. That is, if noise cancellation processing is performed before delay processing of each received signal, the simultaneity of electromagnetic noise components can be ensured, so that the cancellation effect can be enhanced.

1 is a block diagram showing a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention. It is a block diagram which shows the structural example of the noise cancellation control part shown in FIG. 3 is a timing chart for explaining the operation of the circuit shown in FIG. 2. It is a conceptual diagram for demonstrating the electromagnetic noise which appears on an ultrasonic image.

Explanation of symbols

  10 probe (eclipse probe), 12 signal line, 14 dummy signal line, 16 vibration element, 18 dummy vibration element (capacitor), 26 noise cancellation circuit (differential amplifier), 44 noise cancellation control unit, 46 electrocardiograph, 100 ECG signal, 102 gate signal, 106 cancel signal.

Claims (5)

Gate signal generating means for generating a gate signal based on a first reference signal including electromagnetic noise generated in an external device;
In the noise cancellation period based on the gate signal, the received signal obtained by transmitting and receiving the ultrasonic wave includes a signal that is the same as or different from the first reference signal and includes electromagnetic noise generated in the external device. 2 noise cancellation means for performing noise cancellation processing using the reference signal;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
An intracorporeal probe having an insertion tube that is inserted into a body cavity with an ultrasonic transducer;
The insertion tube includes an electromagnetic noise transmission signal line that transmits the electromagnetic noise without transmitting an electrical signal for transmission and reception;
The second reference signal is a signal transmitted from the electromagnetic noise transmission signal line.
An ultrasonic diagnostic apparatus. The apparatus of claim 2.
The first reference signal is an electrocardiogram signal;
The gate signal generating means generates the gate signal by determining that the amplitude of the electrocardiographic signal continuously exceeds a predetermined threshold;
An ultrasonic diagnostic apparatus. The apparatus of claim 1.
Both the first reference signal and the second reference signal are electrocardiogram signals,
An ultrasonic diagnostic apparatus, wherein the gate signal is generated based on the electrocardiogram signal and the noise canceling process is executed. Gate signal generating means for generating a gate signal based on an electrocardiogram signal including electromagnetic noise from an electric knife used during surgery;
Noise subjected to noise cancellation processing using a dummy reception signal including electromagnetic noise from the external device for a plurality of reception signals obtained by transmission / reception of ultrasonic waves in a noise cancellation period based on the gate signal Cancellation means,
Adding means for adding a plurality of reception signals individually subjected to the noise cancellation processing and outputting beam data;
An ultrasonic diagnostic apparatus comprising:

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