JP5161597B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus capable of accurately measuring high-speed blood flow information by using an ultrasonic continuous wave.

  The ultrasonic diagnostic apparatus radiates an ultrasonic pulse (transmitted ultrasonic wave) generated from a vibration element incorporated in an ultrasonic probe into a subject, and a reflected wave (received ultrasonic wave) generated by a difference in acoustic impedance of the subject tissue. ) Is converted into an electrical signal by the vibration element and displayed on a monitor. This diagnostic method is widely used for functional diagnosis and morphological diagnosis of various organs because two-dimensional image data and three-dimensional image data can be observed in real time with a simple operation by simply bringing an ultrasonic probe into contact with the body surface. . Ultrasound diagnostic methods for obtaining biological information from reflected waves from tissues or blood cells in a living body have made rapid progress through the development of two major technologies, the ultrasonic pulse reflection method and the ultrasonic Doppler method. The B-mode image and the color Doppler image that are obtained are indispensable in today's ultrasonic image diagnosis.

  On the other hand, there is a Doppler spectrum method as a method for quantitatively measuring a blood flow velocity in a region of interest of a subject, and this Doppler spectrum method is classified into a pulse Doppler spectrum method and a continuous wave Doppler spectrum method. In the pulse Doppler spectrum method, transmission / reception of ultrasonic pulses is performed a plurality of times at predetermined time intervals with respect to the direction of the region of interest. The received signal component based on the reflected wave (hereinafter referred to as clutter component) and the received signal component based on the reflected wave from the blood cell (hereinafter referred to as blood flow Doppler component) are extracted. Then, frequency spectrum data is generated by performing FFT analysis on the blood flow Doppler component detected by filtering these received signal components, and the same is applied to the received signal components obtained at predetermined time intervals from the region of interest. Spectrum image data is generated by arranging a plurality of frequency spectrum data obtained by processing in time series.

  In contrast to the pulse Doppler spectrum method described above, in the continuous wave Doppler spectrum method, ultrasonic continuous waves are transmitted and received in the direction of the region of interest, and the received blood signal obtained at this time is filtered to detect the blood flow Doppler component. (Fast Fourier Transform) Analyzes to generate frequency spectrum data. Then, spectrum image data is generated by arranging a plurality of frequency spectrum data obtained in time series in the time direction.

  That is, in the pulse Doppler spectrum method, blood flow information from a region of interest can be selectively extracted by applying a sample gate, but the maximum blood flow velocity that can be measured depends on the repetition frequency of the ultrasonic pulse. For this reason, when blood flow is measured at a high flow rate, a phenomenon of folding occurs in the frequency spectrum data, making accurate blood flow measurement difficult. On the other hand, in the continuous wave Doppler spectrum method, it is impossible to extract only blood flow information from the region of interest, but since the above-mentioned folding phenomenon does not occur, it is widely used for blood flow measurement of the region of interest exhibiting a high flow rate. It is used.

  By the way, the DC power supply unit of the ultrasonic diagnostic apparatus used for blood flow measurement as described above usually uses a switching power supply capable of high efficiency, downsizing, and low cost, and switching caused by this switching power supply. In some cases, noise (that is, harmonic components of the switching drive signal) is mixed into a minute reception signal collected from the subject, which makes it difficult to observe frequency spectrum data or spectrum image data. Such switching noise can be reduced by measures such as the insertion of a filter circuit to the output part of the switching power supply and the power supply line, the shielding of the switching power supply and the power supply line, and the ground strengthening of the device body and the power supply part. However, it is extremely difficult to keep it below the clinically acceptable level.

  FIG. 10 shows frequency spectrum data in which line spectra Nx (m) and Nx (m + 1) of switching noise, which are the m-th and m + 1-th harmonics of the switching drive signal, are mixed in the blood flow Doppler component Dvx (FIG. 10A). ) And spectrum image data (FIG. 10 (b)), and in the frequency spectrum data shown in FIG. 10 (a), switching noise line spectrum Nx (m) and line spectrum Nx (m + 1). Is shown adjacent to the spectrum Dvx of the blood flow Doppler component.

  On the other hand, FIG. 10B is spectrum image data showing the temporal change of the frequency spectrum shown in FIG. 10A. Usually, the vertical axis represents Doppler frequency or blood flow velocity, and the horizontal axis represents time. The magnitude (power) of the spectrum is expressed by luminance. In this spectrum image data, the temporal change Nox (m) of the line spectrum Nx (m) and the temporal change Nox (m + 1) of the line spectrum Nx (m + 1) are linear with respect to the temporal change Dox of the spectrum Dvx. It is superimposed as noise.

In response to such problems of the Doppler spectrum method, the pulse Doppler spectrum method focuses on the fact that the line spectrum of the clutter component is located at an integer multiple of the repetition frequency (rate frequency) of ultrasonic transmission and reception. A method of removing the clutter component and the switching noise by the same filtering process by setting the frequency of the switching drive signal so that the spectrum is an integral multiple of the rate frequency has been proposed (for example, see Patent Document 1). .
JP 05-130992 A

  According to the method described in Patent Document 1 described above, the influence of switching noise mixed in the received signal of the pulse Doppler spectrum method can be easily removed. However, it is impossible to remove the influence of switching noise mixed in the received signal of the continuous wave Doppler spectrum method in which ultrasonic continuous waves are used, and to eliminate the influence of this switching noise. There are no proposals yet for other possible ways.

  The present invention has been made in view of such conventional problems, and its purpose is to easily eliminate periodic noise such as switching noise mixed in a received signal collected in the continuous wave Doppler spectrum method. It is an object of the present invention to provide an ultrasonic diagnostic apparatus that can be removed.

In order to solve the above problems, an ultrasonic diagnostic apparatus according to a first aspect of the present invention includes an ultrasonic probe having a vibration element, and an ultrasonic continuous wave in a predetermined direction of a subject by driving the vibration element. Obtained by transmission / reception means for performing transmission / reception, transmission / reception control means for setting an ultrasonic frequency of the ultrasonic continuous wave, reference signal generation means for generating a reference signal having a frequency corresponding to the ultrasonic frequency, and the transmission / reception means. Ultrasonic data generation means for detecting a blood flow Doppler component of the received signal and generating frequency spectrum data; and spectrum image data based on the frequency spectrum data supplied in time series from the ultrasonic data generation means an image data generation means for generating, said reference signal on the basis of dividing the drive signal generated by generating DC power, said transmitting and receiving means, the greater And a switching power supply for supplying the DC power to at least one of the wave data generation means and the image data generation means, the switching power supply is configured to generate the DC power by a switching operation based on the driving signal It is characterized by.

According to a third aspect of the present invention, there is provided an ultrasonic diagnostic apparatus of the present invention, an ultrasonic probe having a vibration element, and transmission / reception means for driving the vibration element to transmit / receive an ultrasonic continuous wave in a predetermined direction of a subject. Transmission / reception control means for setting the ultrasonic frequency of the ultrasonic continuous wave, reference signal generation means for generating a reference signal having a frequency corresponding to the ultrasonic frequency, and blood of the received signal obtained by the transmission / reception means Ultrasonic data generation means for detecting flow Doppler components and generating frequency spectrum data, and voice data generation for generating voice data based on the frequency spectrum data using a drive signal generated by dividing the reference signal And voice output means for outputting the voice data, wherein the voice data generation means generates the voice data using the drive signal. It is set to.

  According to the present invention, it is possible to easily remove periodic noise such as switching noise mixed in a received signal collected by the continuous wave Doppler spectrum method. For this reason, observation of spectrum image data and the like and measurement of various blood flow information can be performed accurately, and diagnostic accuracy can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  In an embodiment of the present invention described below, a switching power supply that supplies predetermined DC power to each unit of an ultrasonic diagnostic apparatus involved in generation of spectrum image data when generating spectrum image data in the continuous wave Doppler spectrum method Generates a switching drive signal by dividing the reference signal having a frequency substantially equal to the frequency of the ultrasonic continuous wave supplied from the reference signal generation unit by an integer, and a switching operation based on the switching drive signal To generate the desired DC power. According to this method, the noise caused by the switching power supply mixed in the reception signal obtained by ultrasonic transmission / reception can be easily removed using the filter circuit for removing the clutter signal.

  In the following, the case of removing the switching noise caused by the switching power supply mixed in the reception signal of the continuous wave Doppler spectrum method will be described, but the present invention is not limited to this, and other units included in the ultrasonic diagnostic apparatus are included. Even when the resulting periodic noise is mixed in the received signal, the noise can be easily removed by the same method.

(Device configuration)
The configuration of the ultrasonic diagnostic apparatus and the basic operation of each unit in the embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus according to the present embodiment, and FIG. 2 shows a specific configuration of a transmission / reception unit and an ultrasonic data generation unit provided in the ultrasonic diagnostic apparatus. It is a block diagram.

  An ultrasonic diagnostic apparatus 100 shown in FIG. 1 transmits ultrasonic pulses and ultrasonic continuous waves (collectively referred to as transmission ultrasonic waves) to a diagnosis target region of a subject, and is obtained by these transmission ultrasonic waves. An ultrasonic probe 20 in which a plurality of vibration elements for converting the reflected ultrasonic wave (received ultrasonic wave) into an electric signal (received signal) is arranged, and the vibration element is driven and obtained from these vibration elements. The diagnostic apparatus main body 30 generates ultrasonic data based on the received signals, and generates various image data and audio data using the ultrasonic data, the display unit 40 that displays the various image data, and the audio. An audio output unit 50 for outputting data, an input unit 60 for inputting object information, setting ultrasonic data generation conditions and image data generation conditions, and inputting various command signals, etc. For each unit diagnosis apparatus body 30 is provided and includes a power supply unit 70 supplies predetermined power (voltage / current).

  The ultrasonic probe 20 has N vibration elements (not shown) arranged at its distal end, and transmits and receives ultrasonic waves by bringing the distal end into contact with the body surface of the subject. The vibration element is an electroacoustic transducer, which converts an electrical signal (driving signal) into transmission ultrasonic waves (ultrasonic pulses or continuous ultrasonic waves) during transmission, and converts received ultrasonic waves (ultrasonic reflected waves) during reception. It has a function of converting into an electrical reception signal. Each of these vibration elements is connected to a transmission / reception unit 2 described later provided in the diagnostic apparatus main body 30 via an N-channel multi-core cable (not shown). In this embodiment, the ultrasonic diagnostic apparatus 100 using the sector scanning ultrasonic probe 20 provided with N vibration elements will be described. However, an ultrasonic probe corresponding to linear scanning or convex scanning is used. It doesn't matter.

  Next, the diagnostic apparatus main body 30 supplies a drive signal for transmitting an ultrasonic pulse or an ultrasonic continuous wave in a predetermined direction of the subject to the vibration element, and a plurality of obtained vibration elements are obtained from these vibration elements. A transmission / reception unit 2 that performs phasing addition of the reception signals of the channels (N channel), and an ultrasonic processor that processes the reception signals after the phasing addition and generates various ultrasonic data such as B-mode data, color Doppler data, and frequency spectrum data. An acoustic data generator 3, an image data generator 4 that generates B-mode image data, color Doppler image data, and spectrum image data based on these ultrasonic data, and incidental information such as these image data and subject information Frequency data generated by the display data generation unit 5 that generates display data by combining the above and the ultrasonic data generation unit 3 described above And a voice data generating unit 6 that generates audio data based.

  Furthermore, the diagnostic apparatus main body 30 controls the transmission / reception unit 2 to control the ultrasonic transmission / reception direction, control the convergence point in ultrasonic transmission / reception, and control the ultrasonic frequency and ultrasonic transmission / reception direction in the continuous wave Doppler spectrum method. A transmission / reception control unit 7 to perform and a high-frequency system clock pulse supplied from a system control unit 9 described later divides to generate a reference signal having a frequency substantially equal to the center frequency of the ultrasonic pulse or the frequency of the ultrasonic continuous wave. And a system control unit 9 that comprehensively controls the above-described units included in the diagnostic apparatus main body 30.

  Next, specific configurations of the transmission / reception unit 2 and the ultrasonic data generation unit 3 will be described with reference to FIG. The transmission / reception unit 2 shown in FIG. 2 is obtained from a transmission unit 21 that supplies a drive signal for radiating transmission ultrasonic waves in a predetermined direction of the subject to the vibration element of the ultrasonic probe 20 and these vibration elements. The receiving unit 22 performs phasing addition on the N-channel received signal, and the transmitting unit 21 includes a rate pulse generator 211, a transmission delay circuit 212, and a drive circuit 213.

  The rate pulse generator 211 is applied in the B-mode method, the color Doppler method, and the pulse Doppler spectrum method using an ultrasonic pulse, and determines a repetition period of a transmission ultrasonic wave (ultrasonic pulse) radiated into a subject. Is generated by dividing the reference signal supplied from the reference signal generation unit 8 and supplied to the transmission delay circuit 212.

  The transmission delay circuit 212 includes, for example, the same number (N channels) of independent delay circuits as vibration elements used for ultrasonic transmission, and transmits ultrasonic waves (with a predetermined depth) in order to obtain a narrow beam width in transmission. A delay time for converging an ultrasonic pulse or an ultrasonic continuous wave) and a delay time for emitting the transmission ultrasonic wave in a predetermined direction are set. Then, the drive circuit 213 configured by the N channel generates a drive signal for driving the vibration element built in the ultrasonic probe 20. Specifically, a driving pulse in the B mode method, the color Doppler method, and the pulse Doppler spectrum method is generated based on the rate pulse to which the delay time is given, and further based on a control signal supplied from the transmission / reception control unit 7. Then, a continuous wave for driving of the continuous wave Doppler spectrum method having a predetermined ultrasonic frequency and delay phase is generated.

  On the other hand, the reception unit 22 includes a preamplifier 221, a reception delay circuit 222, and an adder 223. The preamplifier 221 amplifies a minute reception signal converted from a reception ultrasonic wave into an electric signal by the vibration element to ensure sufficient S / N. The reception delay circuit 222 also includes a delay time for converging the received ultrasonic waves from a predetermined depth and a delay time for setting a strong reception directivity with respect to the received ultrasonic waves from the predetermined direction. Is given to the received signal output from Then, the reception signal given a predetermined delay time in the reception delay circuit 222 is sent to the adder 223, and the adder 223 performs addition synthesis (phased addition).

  Next, the ultrasonic data generation unit 3 performs a predetermined signal processing on the reception signal output from the adder 223 of the reception unit 22 to generate B mode data, and the reception signal A frequency conversion unit 32 that performs frequency conversion, a color Doppler data generation unit 33 that extracts a blood flow Doppler component from the received signal after frequency conversion, and generates color Doppler data based on the blood flow Doppler component, and frequency conversion A blood flow Doppler component is extracted from the later received signal, and a spectrum data generation unit 34 for generating frequency spectrum data in the pulse Doppler spectrum method and the continuous wave Doppler spectrum method by performing FFT analysis on the blood flow Doppler component is provided.

  Note that the frequency conversion unit 32, the color Doppler data generation unit 33, and the spectrum data generation unit 34 that are applied to the color Doppler method and the pulse Doppler spectrum method in which the effect of the present invention is not directly reflected are disclosed in Japanese Patent Application Laid-Open No. 2005-81081. The detailed description is omitted because it is described, and in the following, the B mode data generation unit 31 applied to the B mode method, the frequency conversion unit 32 and the spectrum data generation unit 34 applied to the continuous wave Doppler spectrum method are described. State.

  The B mode data generation unit 31 includes a logarithmic converter 311, an envelope detector 312, and an A / D converter 313. The logarithmic converter 311 logarithmically converts the amplitude of the received signal supplied from the adder 223 of the receiving unit 22 to relatively emphasize the weak signal, and the envelope detector 312 envelopes the logarithmically converted received signal. Only amplitude information is detected by line detection. Then, the A / D converter 313 performs A / D conversion on the received signal subjected to the envelope detection, and generates B-mode data.

  The frequency conversion unit 32 includes a π / 2 phase shifter 321, mixers 322-1 and 322-2, and LPFs (low-pass filters) 323-1 and 323-2, and is supplied from the reception unit 22 of the transmission / reception unit 2. The received signal is subjected to quadrature detection to convert the frequency of the received signal. On the other hand, the spectrum data generation unit 34 includes a high-pass filter (HPF) 341, a low-pass filter (LPF) 342, an A / D converter 343, and an FFT analyzer 344, and is extracted from the received signal after frequency conversion. The blood flow Doppler component is subjected to FFT analysis to generate frequency spectrum data in the continuous wave Doppler spectrum method.

  Next, basic operations of the frequency conversion unit 32 and the spectrum data generation unit 34 in the continuous wave Doppler spectrum method will be described. The reception signal output from the adder 223 of the reception unit 22 in the continuous wave Doppler spectrum method is input to the first input terminals of the mixers 322-1 and 322-2 of the frequency conversion unit 32.

  On the other hand, a reference signal having a frequency equal to the frequency of the received signal (ultrasonic frequency) is directly supplied from the reference signal generator 8 to the second input terminal of the mixer 322-1 and further a π / 2 phase shifter. A reference signal whose phase is shifted by 90 degrees through 321 is supplied to the second input terminal of the mixer 322-2. The outputs of the mixers 322-1 and 322-2 are sent to the LPFs 323-1 and 323-2, and the frequency of the reception signal output from the adder 223 and the frequency of the reference signal supplied from the reference signal generator 8 Are removed, and only the difference component is detected.

  Next, the frequency-converted received signals output from the LPFs 323-1 and 323-2 are supplied to the HPF 341 and the LPF 342 of the spectrum data generation unit 34, and the HPF 341 and the LPF 342 are transmitted from the living tissue included in the received signals. The clutter component based on the reflected wave and the switching noise caused by the power supply unit 70 mixed in the received signal are removed, and only the blood flow Doppler component based on the reflected wave from the blood cell is extracted. However, the above-described HPF 341 and LPF 342 may be configured in a different order, and a BPF (band pass filter) may be used instead of the HPF 341 and LPF 342.

  The blood flow Doppler component extracted by removing the above-described unnecessary components by the HPF 341 and the LPF 342 is converted into a digital signal by the A / D converter 343 and supplied to the FFT analyzer 344. The FFT analyzer 344 Frequency spectrum data is generated by performing FFT analysis on the blood flow Doppler component after A / D conversion. The switching noise superimposed on the received signal including the blood flow Doppler component and the clutter component described above and details of the removal method will be described later.

  Returning to FIG. 1, the image data generation unit 4 includes a B-mode data storage unit, a color Doppler data storage unit, and a spectrum data storage unit (not shown). The B-mode image is stored in the B-mode data storage unit in correspondence with the ultrasonic transmission / reception direction by sequentially storing the B-mode data supplied from the B-mode data generation unit 31 along with the ultrasonic transmission / reception with respect to the subject. Similarly, the color Doppler data supplied from the color Doppler data generation unit 32 is stored in the color Doppler data storage unit to generate color Doppler image data. Further, the image data generation unit 4 sequentially stores the frequency spectrum data supplied in time series from the spectrum data generation unit 34 in the pulse Doppler spectrum method or the continuous wave Doppler spectrum method in the spectrum data storage unit to store the spectrum image data. Generate.

  Next, the display data generation unit 5 receives the above-described B-mode image data, color Doppler image data, spectrum image data in the pulse Doppler spectrum method and continuous wave Doppler spectrum method, and additional information such as subject information as necessary. Are combined and subjected to predetermined conversion processing to generate display data. The generated display data is displayed on a CRT monitor, a liquid crystal monitor or the like provided in the display unit 40. In particular, when displaying spectrum image data generated by the pulse Doppler spectrum method or the continuous wave Doppler spectrum method, B-mode image data on which markers indicating the direction of ultrasonic transmission / reception and the position of the sample gate at this time are superimposed. Displayed with spectrum image data.

  On the other hand, the audio data generation unit 6 receives time-series frequency spectrum data supplied from the ultrasonic data generation unit 3 in the pulse Doppler spectrum method or the continuous wave Doppler spectrum method, and for example, the maximum frequency component in the frequency spectrum data Audio data corresponding to the temporal change in (maximum flow velocity value) is generated. The generated audio data is supplied to a speaker provided in the audio output unit 50 and converted into audio. That is, the operator can grasp the temporal change of the frequency spectrum data by the sound output from the speaker.

  Next, the power supply unit 70 illustrated in FIG. 1 includes a switching power supply 71 and a filter circuit 72. The switching power supply 71 includes a switching drive signal generation unit and a switching unit (not shown) including elements such as a switching element, a capacitor, a coil, and a diode. It has a function of converting AC power into desired DC power.

  The switching drive signal generation unit divides a reference signal having a frequency substantially equal to the center frequency of the ultrasonic pulse or the frequency of the ultrasonic continuous wave supplied from the reference signal generation unit 8 of the diagnostic apparatus main body 30 into an integer. The switching drive signal is generated by the rotation, and the switching drive signal is supplied to the switching element of the switching unit to generate desired DC power. In this case, the magnitude of the DC voltage output from the switching power supply 71 is determined by the input voltage and the ratio (duty ratio) of the ON / OFF time in the switching unit.

  FIG. 3 shows a switching drive signal (FIG. 3A) having a period Ts generated in the switching drive signal generation unit of the switching power supply 71, and switching noise (switching drive) generated in the switching unit supplied with the switching drive signal. The frequency spectrum (FIG.3 (b)) of the harmonic component of a signal is shown.

  For example, the switching drive signal having the switching frequency fs (fs = 1 / Ts = f0 / m) is obtained by dividing the reference signal of the frequency f0 supplied from the reference signal generator 8 by 1 / m (m is an integer). Is generated as a line spectrum at a position that is an integral multiple of the switching frequency fs, and its magnitude depends on the above-described duty ratio. At this time, the harmonic component fs (m) = mfs that is m times the switching frequency fs and the reference signal frequency (that is, the ultrasonic frequency in the continuous wave Doppler spectrum method) f0 coincide on the frequency axis. The DC power of the switching power supply 71 on which switching noise having such frequency characteristics is superimposed is supplied to the filter circuit 72.

  The filter circuit 72 is connected to the output terminal of the switching power supply 71 and reduces switching noise that enters the diagnostic device main body 30 from the switching power supply 71 via the DC power supply line. The DC power from which the switching noise has been removed by the filter circuit 72 is supplied to each unit of the diagnostic apparatus main body 30. Note that the higher the switching frequency fs, the easier the miniaturization of the switching power supply 71. However, the switching noise that enters the diagnostic device main body 30 from the switching power supply 71 in the air or via the power supply line increases as the switching frequency increases. Therefore, the switching noise mixed in the received signal also increases. In order to reduce the mixing of such switching noise, measures such as insertion of the filter circuit 72 to the output terminal of the switching power supply 71 and attachment of a shield material (not shown) have been conventionally performed. It is extremely difficult to reduce the switching noise mixed in the received signal to an allowable level or less by such a method.

  Next, switching noise superposed on the reception signal having the blood flow Doppler component and the clutter component in the present embodiment and the removal thereof will be described with reference to FIGS.

  FIG. 4 is a diagram for explaining the frequency conversion of the received signal performed by the frequency conversion unit 32. FIG. 4A is supplied from the adder 223 of the reception unit 22 to the mixer 322 of the frequency conversion unit 32. The frequency spectrum of the received signal before frequency conversion and the frequency spectrum of the switching noise caused by the switching power supply 71 mixed in the received signal are shown. The received signal in this case has a clutter component Dt distributed around the ultrasonic frequency f0 in the continuous wave Doppler spectrum method and a blood flow Doppler component Dv distributed around the frequency f0 + fd. Here, fd is a Doppler shift frequency due to blood flow.

  On the other hand, the switching noise caused by the switching power supply 71 is distributed as a line spectrum at an integer multiple of the switching frequency fs as already shown in FIG. Since it is set to 1 / m times the acoustic wave frequency f0, the m-th line spectrum N (m) of switching noise distributed around the frequency fs (m) and the clutter component of the received signal distributed around the frequency f0. Dt is superposed.

  The received signal and switching noise having such a frequency spectrum are converted into a frequency spectrum as shown in FIG. That is, the clutter component of the received signal and the m-th line spectrum N (m) of the switching noise distributed around the ultrasonic frequency f0 in FIG. 4 (a) are shifted in the negative direction by the frequency f0 and the frequency is zero. Similarly, other line spectra of blood flow Doppler components and switching noise that are located in the vicinity and distributed around the frequency f0 + fd are also shifted in the negative direction by the frequency f0.

  Next, FIG. 5 shows a filtering process performed by the spectrum data generation unit 34 in the continuous wave Doppler spectrum method on the reception signal frequency-converted by the frequency conversion unit 32. This filtering process is performed by generating spectrum data. This is performed by the HPF 341 and the LPF 342 included in the unit 34.

  That is, in FIG. 5A, the clutter component Dt and switching noise line spectrum N (m) distributed in the vicinity of zero frequency are removed by the HPF 341 having a predetermined cutoff frequency ± fa, and further, the switching noise line spectrum N (1) to N (m−1) and line spectra N (m + 1), N (m + 2),... Are removed by the LPF 342 having the cutoff frequency ± fb, and the blood flow Doppler component Dv shown in FIG. Is extracted.

  Here, the frequency spectrum of the received signal and the switching noise after the frequency conversion obtained by the conventional method of setting the switching frequency fs of the switching power supply 71 independently of the ultrasonic frequency f0, and the received signal and the switching noise. A filtering process performed by the spectrum data generation unit 34 will be described with reference to FIG.

  In this case, the switching noise exists as a line spectrum at a position that is an integral multiple of the switching frequency fs in the same manner as described above. However, these line spectra do not always coincide with the ultrasonic frequency f0 in the continuous wave Doppler spectrum method. In some cases, the switching noise exists outside the cutoff band formed by the HPF 341 and the LPF 342 as in the line spectrum N (m) or the line spectrum N (m + 1) of the switching noise shown in FIG. Accordingly, such a line spectrum N (m) and line spectrum N (m + 1) cannot be removed by filtering processing using the HPF 341 and the LPF 342, and the blood flow Doppler component Dv as shown in FIG. 6B. Is output from the LPF 342 in a mixed state.

  That is, it is extremely difficult to reduce the switching noise mixed in the received signal to an allowable level or less by the conventional method in which the switching frequency fs of the switching power supply 71 is set independently with respect to the ultrasonic frequency f0 in the continuous wave Doppler spectrum method. However, by setting the switching frequency fs to be 1 / integer of the ultrasonic frequency f0 as shown in the present embodiment, it is possible to significantly reduce the switching noise mixed in the received signal.

  Next, a specific example of spectrum image data in the present embodiment and the conventional continuous wave Doppler spectrum method will be described with reference to FIG.

  FIG. 7 shows the present embodiment and conventional spectrum image data generated by arranging the frequency spectrum data generated by the spectrum data generation unit 34 in time series. FIG. 7A shows the method of this embodiment. FIG. 7B shows the spectrum image data having only the blood flow Doppler component Dv obtained by the conventional method (that is, the switching frequency fs of the switching power supply 71 is compared with the ultrasonic frequency f0 of the continuous wave Doppler spectrum method). The spectrum image data in which switching noises having line spectra Nx (m) and Nx (m + 1) are mixed in the blood flow Doppler component Dv are shown respectively.

  As is clear from the comparison of these spectrum image data, the linear noise components NL (m) and NL (m + 1) superimposed on the time-series blood flow information Do in the conventional spectrum image data are the same as those in this embodiment. Thus, by setting the switching frequency fs of the switching power supply 71 to 1 / integer of the ultrasonic frequency f0, it is possible to reduce to an acceptable level.

  According to the present embodiment described above, it is possible to easily and reliably remove the switching noise caused by the switching power supply mixed in the reception signal of the continuous wave Doppler spectrum method. For this reason, observation of spectrum image data and measurement of various blood flow information can be performed accurately, and diagnostic accuracy can be improved.

  In particular, in this embodiment, the switching noise superimposed on the clutter component can be removed by using a filter circuit provided in the spectrum data generation unit of the ultrasonic data generation unit for the purpose of removing the clutter component. For this reason, it is not necessary to newly provide a filter circuit for the purpose of removing the switching noise, and the configuration of the apparatus is simplified.

  As mentioned above, although the Example of this invention has been described, this invention is not limited to the above-mentioned Example, It can change and implement. For example, in the above-described embodiment, the switching noise when the single phase switching power supply 71 is used has been described. However, a multiphase switching power supply may be used.

  FIG. 8 is a diagram for explaining a multi-phase switching power supply 71a. The switching power supply 71a generates, for example, a switching drive signal for generating a three-channel switching drive signal, as shown in FIG. 8A. Unit 711 and a switching unit 712 for converting DC power supplied from its own input terminal or commercial AC power into desired DC power based on the switching drive signal. This switching unit 712 is a three-channel switching element. 713 to 715, a smoothing coil 716 and a capacitor 717 are provided. Then, the switching drive signal generation unit 711 supplies each of the switching elements 713 to 715 with a three-channel switching drive signal whose phase is shifted by 2π / 3 as shown in FIGS. 8B to 8D. Thus, conversion to desired DC power is performed.

  In this case, even if the switching frequency of the switching drive signal supplied to each of the switching elements 713 to 715 is fs as in the above-described embodiment, the switching frequency fsa of the switching power supply 71a is 3 fs. Therefore, by setting the switching frequency fsa to 1 / integer of the ultrasonic frequency f0, it is possible to easily remove the switching noise generated from the switching power supply 71a, and further, the interval between adjacent line spectra in the switching noise. Is three times as compared with the case of FIG. 5A, the cutoff frequency fb of the LPF 342 can be set high, and therefore the blood flow Doppler component Dv having a high flow velocity value can be measured.

  In an ultrasonic diagnostic apparatus using a plurality of types of switching power supplies, it is desirable to set the switching frequency as described above for all switching power supplies, but it is directly involved in the generation of spectrum image data. The switching power supply of the unit may be preferentially performed, and the switching frequency of the switching power supply such as the display unit 40 or the input unit 60 may be set independently of the ultrasonic frequency f0.

  On the other hand, in the above-described embodiment, the case of removing the switching noise caused by the switching power supply 71 mixed in the reception signal of the continuous wave Doppler spectrum method has been described. However, the present invention is not limited to this. Even when periodic noise generated in the A / D converter 343, the audio data output unit 6 and the like is mixed in the received signal, the conversion frequency and drive frequency in these units are reduced to 1 / integer of the ultrasonic frequency f0. By setting to, it becomes possible to remove the above-mentioned noise.

  For example, in an audio data output unit 6 including a maximum frequency detection unit that detects a maximum frequency component in frequency spectrum data and a PW conversion unit (none of which is shown) that converts a temporal change in the maximum frequency into a pulse width. The maximum frequency detection unit detects the maximum frequency in the time-series frequency spectrum data supplied from the spectrum data generation unit 34 of the ultrasonic data generation unit 3, and the PW conversion unit is shown in FIG. Audio data (FIG. 9B) having a pulse width W corresponding to the maximum frequency change Dm shown and a predetermined conversion frequency fc (fc = 1 / Tc, Tc is a conversion cycle) is generated. At this time, by setting the above-described conversion frequency fc to 1 / integer of the ultrasonic frequency f0, it is possible to easily remove noise caused by the audio data mixed in the received signal.

  When periodic noise generated from a plurality of units is mixed in the received signal, it is desirable to set all of the conversion frequency and drive frequency in these units to 1 / integer of the ultrasonic frequency f0. The conversion frequency and the drive frequency with the largest degree may be set preferentially by the above method.

1 is a block diagram showing the overall configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. The block diagram which shows the specific structure of the transmission / reception part with which the ultrasonic diagnostic apparatus of the Example is provided, and an ultrasonic data generation part. The figure which shows the line spectrum of the switching noise generate | occur | produced with the switching power supply of the Example. The figure for demonstrating the frequency conversion of the received signal performed in the frequency conversion part of the Example. The figure for demonstrating the filtering process with respect to the received signal after the frequency conversion performed in the spectrum data generation part of the Example. The figure for demonstrating the filtering process with respect to the received signal after the frequency conversion performed in the conventional spectrum data generation part. The figure which shows the spectrum image data produced | generated by the continuous wave Doppler spectrum method in the Example of this invention, and the conventional continuous wave Doppler spectrum method. The figure for demonstrating the multiphase switching power supply in the modification of the Example. The figure which shows the specific example of the audio | voice data produced | generated in the audio | voice data production | generation part of the Example. The figure which shows the conventional frequency spectrum data and spectrum image data in which switching noise was mixed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Ultrasonic probe 30 ... Diagnostic apparatus main body 2 ... Transmission / reception part 21 ... Transmission part 211 ... Rate pulse generator 212 ... Transmission delay circuit 213 ... Drive circuit 22 ... Reception part 221 ... Preamplifier 222 ... Reception delay circuit 223 ... Adder 3 ... Ultrasonic data generator 31 ... B-mode data generator 311 ... Logarithmic converter 312 ... Envelope detector 313 ... A / D converter 32 ... Frequency converter 321 ... π / 2 phase shifter 322 ... Mixer 323 ... LPF (Low-pass filter)
33 ... Color Doppler data generation unit 34 ... Spectrum data generation unit 341 ... HPF (high pass filter)
342 ... LPF (low pass filter)
343 ... A / D converter 344 ... FFT analyzer 4 ... Image data generator 5 ... Display data generator 6 ... Audio data generator 7 ... Transmission / reception controller 8 ... Reference signal generator 9 ... System controller 40 ... Display unit DESCRIPTION OF SYMBOLS 50 ... Audio | voice output part 60 ... Input part 70 ... Power supply part 71, 71a ... Switching power supply 711 ... Switching drive signal generation part 712 ... Switching part 713-715 ... Switching element 716 ... Coil 717 ... Capacitor 72 ... Filter part 100 ... Ultrasonic Diagnostic equipment

Claims (5)

An ultrasonic probe having a vibration element;
A transmission / reception means for driving the vibration element to transmit / receive an ultrasonic continuous wave in a predetermined direction of the subject;
A transmission / reception control means for setting an ultrasonic frequency of the ultrasonic continuous wave;
A reference signal generating means for generating a reference signal having a frequency corresponding to the ultrasonic frequency;
Ultrasonic data generating means for detecting the blood flow Doppler component of the received signal obtained by the transmitting / receiving means and generating frequency spectrum data;
Image data generating means for generating spectrum image data based on the frequency spectrum data supplied in time series from the ultrasonic data generating means;
Said reference signal on the basis of dividing the drive signal generated by generating DC power, said transmitting and receiving means, for supplying the DC power to at least one of the ultrasound data generation means and the image data generating means Switching power supply,
The switching power supply, the ultrasonic diagnostic apparatus characterized by generating the DC power by a switching operation based on the drive signal.   The ultrasonic diagnostic apparatus according to claim 1, wherein the switching power supply is a multiphase switching power supply. An ultrasonic probe having a vibration element;
A transmission / reception means for driving the vibration element to transmit / receive an ultrasonic continuous wave in a predetermined direction of the subject;
A transmission / reception control means for setting an ultrasonic frequency of the ultrasonic continuous wave;
A reference signal generating means for generating a reference signal having a frequency corresponding to the ultrasonic frequency;
Ultrasonic data generating means for detecting the blood flow Doppler component of the received signal obtained by the transmitting / receiving means and generating frequency spectrum data;
Audio data generating means for generating audio data based on the frequency spectrum data using a drive signal generated by dividing the reference signal ;
Voice output means for outputting the voice data,
The ultrasonic diagnostic apparatus, wherein the voice data generation means generates the voice data using the drive signal. The ultrasonic diagnostic apparatus according to claim 1, wherein the drive signal has a repetition frequency that is 1 / integer of the ultrasonic frequency. The ultrasonic data generation means includes a filter circuit, and the filter circuit is caused by a clutter component from a living tissue included in the received signal and the drive signal having a center frequency substantially equal to a center frequency of the clutter component. ultrasonic diagnostic apparatus according to claim 1 or claim 3 noise components are removed, and detects the blood flow Doppler components.

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