JP2010274068A - Ultrasonic diagnostic apparatus and image display method in ultrasonic diagnostic apparatus - Google Patents

Abstract

An ultrasonic diagnostic apparatus that makes it easy to recognize a boundary between a blood flow signal and a noise region, reduces an operator's burden, and shortens a diagnosis time.
Transmission / reception means for transmitting / receiving an ultrasonic beam to / from a diagnostic site including a moving body in a subject, and the moving body at a position of a desired range gate from a reception signal obtained by the transmission / reception means Extraction means for extracting the Doppler signal, frequency analysis means for calculating a Doppler spectrum from the extracted Doppler signal, and a Doppler in a partial range excluding a partial range where the calculated intensity of the Doppler spectrum is smaller Adjusting means for changing the intensity of the spectrum; and display control means for displaying the Doppler spectrum changed by the adjusting means on the display unit with luminance based on the intensity.
[Selection] Figure 1

Description

  The present invention relates to an ultrasonic diagnostic apparatus and an image display method in the ultrasonic diagnostic apparatus, and in particular, an ultrasonic diagnostic apparatus and an ultrasonic diagnostic apparatus for diagnosing the motion state of a moving body such as blood using the Doppler effect of ultrasound. The present invention relates to an image display method in an ultrasonic diagnostic apparatus.

  Conventionally, the ultrasonic pulse Doppler method and the ultrasonic pulse reflection method are used together to obtain a tomographic image (monochrome B-mode image) and blood flow information with a single ultrasonic probe, and at least display the blood flow information in real time. Such an ultrasonic Doppler diagnostic apparatus is known.

  A conventional ultrasonic Doppler diagnostic apparatus will be described with reference to FIGS. 11 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus, FIG. 12 is a timing chart, and FIG. 13 is a frequency spectrum pattern.

  This ultrasonic Doppler diagnostic apparatus measures blood flow velocity as blood flow information. The ultrasonic diagnostic apparatus includes a transmission pulser 202 and a reception preamplifier 203 connected to the ultrasonic probe 201. On the output side of the preamplifier 203, a mixer 204, a low pass filter 205, a sample hold circuit 206, a band pass filter 207, a Doppler spectrum calculation unit 208 that is a frequency analyzer, a gain adjustment circuit 209, and a dynamic range adjustment circuit 210 are provided. To the display 211.

  The ultrasonic Doppler diagnostic apparatus further includes a pulse generation circuit 212 for transmission control and reception control, and a range gate circuit 213 for range gate control. The pulse generation circuit 212 includes a frequency dividing circuit, a gate circuit, and the like, generates a clock pulse a having a predetermined frequency (see FIG. 12), supplies the clock pulse a to the range gate circuit 213 and the mixer 204, and A rate pulse b (see FIG. 12) corresponding to the ultrasonic repetition frequency is generated based on the clock pulse a, and the rate pulse b is supplied to the pulser 202 and the range gate circuit 213.

  The pulser 202 generates a high-voltage drive voltage pulse based on the supplied rate pulse b, and excites the ultrasonic probe 201 with the drive voltage pulse. Accompanying this excitation, the ultrasonic probe 201 transmits an ultrasonic pulse signal into the living body P. A part of the transmitted ultrasonic pulse signal is reflected by the blood vessel wall in the living body P and the blood flow B (mainly red blood cells) in the blood vessel to become an ultrasonic echo signal. This ultrasonic echo signal is received again by the same ultrasonic probe 201 and converted into a voltage echo signal d (see FIG. 12).

  This voltage echo signal d is a reception signal reflecting the Doppler effect of ultrasonic waves. That is, when an ultrasonic pulse is transmitted to the blood flow flowing in the living body P, it is scattered by the flowing blood cells and undergoes Doppler shift. For this reason, the center frequency fc of the ultrasonic beam changes by fd, and the reception frequency f becomes f = fc + fd. The Doppler shift frequency fd is expressed as follows in terms of the blood flow velocity v, the angle θ between the ultrasonic beam and the blood vessel, and the sound velocity c.

fd = {(2 · v · cos θ · fc) / c} · fc
For this reason, since the blood flow velocity v can be known by detecting the Doppler shift frequency fd from the received voltage signal, the reception path described above operates for this detection.

  That is, the preamplifier 203 amplifies the voltage echo signal d and outputs the amplified signal to the mixer 204. The mixer 204 mixes the amplified voltage echo signal d and the clock pulse a, and outputs the mixed signal to the low-pass filter 205 at the next stage. The low-pass filter 205 removes high-frequency components such as the ultrasonic carrier frequency from the input mixed signal, and outputs only the low-frequency component centered on the Doppler shift frequency fd to the sample-and-hold circuit 206.

  The sample hold circuit 206 extracts a Doppler shift signal only for the observation position of the velocity of the blood flow B, that is, the position of the range gate (sampling point or sampling volume) with respect to the blood flow B on the sampling raster. Circuit. In order to perform this signal extraction, a sampling pulse c is supplied from the range gate circuit 213 to the sample hold circuit 206. The range gate circuit 213 is a circuit in which the delay time can be arbitrarily set. The range gate circuit 213 delays the ultrasonic pulse from the rate pulse b by a time equal to the round-trip propagation between the ultrasonic probe 201 and the range gate position O, and is set. A sampling pulse c (see FIG. 12) having the pulse width thus formed is formed, and this sampling pulse c is supplied to the sample hold circuit 206. Note that the range gate position O is arbitrarily set by the operator at the position of the blood vessel on which the blood flow velocity on the B-mode slice is desired with a trackball or a joystick.

  The sample hold circuit 206 samples and holds the output signal of the low pass filter 205 with the sampling pulse c corresponding to the range gate position O from the body surface, and outputs the hold result to the band pass filter 207. The band pass filter 207 removes the Doppler shift frequency due to the harmonic component generated by the sampling of the sample hold circuit 206, the fixed reflection signal such as the blood vessel, and the relatively slow movement in the living body, and the Doppler shift of the blood flow B. Only the frequency is extracted. This extracted signal is sent to a Doppler spectrum calculation unit 208 which is a frequency analyzer at the next stage, and a frequency spectrum pattern (Doppler spectrum) of a Doppler shift frequency is calculated by frequency analysis such as fast Fourier transform (FFT). This frequency spectrum pattern shows the change of the Doppler shift frequency (corresponding to blood flow velocity: vertical axis, the intensity of each frequency component is expressed in luminance) over time (horizontal axis), and gain adjustment After passing through the circuit 209 and the dynamic range adjustment circuit 210, it is displayed on the display 211 in real time as shown in FIG. 13, for example (for example, Patent Document 1).

Japanese Patent Laid-Open No. 8-308843

  However, in the ultrasonic diagnostic apparatus described in the above-mentioned patent document, even if the operator sets the gain setting of the operation unit high when the S / N is bad, both the signal and noise are displayed with high brightness, and the difference between them is It is difficult to see and it is difficult to recognize the boundary between the blood flow signal and the noise region, which is a heavy burden on the operator. At the same time, the diagnosis took a great deal of time.

  The present invention solves the above-described problems, and has been made in view of such problems of the prior art. The Doppler spectrum in the partial range excluding the partial range of the smaller Doppler spectrum intensity is provided. By changing the intensity, it is possible to increase the difference between the display brightness of the signal and noise, make it easier to recognize the boundary between the blood flow signal and the noise area, reduce the burden on the operator, and shorten the diagnosis time An object is to provide a possible ultrasonic diagnostic apparatus.

In order to solve the above problems, the present invention focuses on assigning as little display luminance as possible to noise and assigning as much display luminance as possible to a signal when assigning display luminance to the intensity of the Doppler spectrum. .
Specifically, according to a first aspect of the present invention, a transmission / reception unit that transmits / receives an ultrasonic beam to / from a diagnostic site including a moving body in a subject, and a desired range from a reception signal obtained by the transmission / reception unit. Extraction means for extracting a Doppler signal resulting from the moving body at the gate position, frequency analysis means for calculating a Doppler spectrum from the extracted Doppler signal, and one of the calculated ones having the smaller intensity of the Doppler spectrum An ultrasonic device comprising: adjusting means for changing the intensity of a Doppler spectrum in a partial range excluding the partial range; and display control means for displaying the Doppler spectrum changed by the adjusting means on a display unit with luminance based on the intensity. It is a diagnostic device.
According to another aspect of the present invention, there is provided a transmission / reception step of transmitting / receiving an ultrasonic beam to / from a diagnostic site including a moving body in a subject, and a desired range gate position from a reception signal obtained by the transmission / reception step. An extraction step for extracting a Doppler signal caused by the moving body, a calculation step for calculating a Doppler spectrum from the extracted Doppler signal, and an instruction by an operation of an operation unit, the calculated Doppler spectrum is When the Doppler spectrum is amplified with a predetermined gain and the intensity of the Doppler spectrum having substantially the same intensity as the predetermined threshold does not reach the predetermined first target value, the Doppler spectrum having substantially the same intensity as the threshold is A change step of changing the intensity of the Doppler spectrum so as to reach a target value; and after the change step, the threshold value Selecting a larger range to make a Doppler spectrum of a partial range, an amplification step of amplifying the Doppler spectrum of the selected partial range with a predetermined gain, and the portion amplified by the amplification step And displaying the Doppler spectrum of the range on the display unit with a luminance based on the intensity thereof.

  According to the present invention, it is possible to reduce the burden on the operator and shorten the diagnosis time.

  Further, according to the first embodiment of the present invention, it is possible to display an easy-to-see Doppler image by changing the Doppler spectrum intensity in the partial range and displaying the Doppler spectrum in the partial range with an appropriate display luminance. It becomes. As a result, the burden on the operator can be reduced and the diagnosis time can be shortened.

  Furthermore, according to the sixth aspect of the present invention, for example, the maximum value of the noise level can be displayed so as to be slightly visible, and the Doppler spectrum in the partial range can be displayed with more appropriate display luminance.

1 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. It is a figure which shows operation | movement of a gain adjustment switch. It is a figure which shows operation | movement of DR switch. It is a figure which shows a Doppler spectrum in case S / N is bad. 4A is a diagram showing a Doppler spectrum when the gain adjustment switch setting is increased in the case shown in FIG. 4, and FIG. 4B is a diagram showing a Doppler spectrum when the DR switch setting is reduced in FIG. It is a figure which shows a spectrum. It is a figure which shows a series of operation | movement of an ultrasonic diagnosing device. It is a flowchart which shows a series of operation | movement of an adjustment means. It is a figure which shows a series of operation | movement of the ultrasonic diagnosing device which concerns on 2nd Embodiment of this invention. It is a figure which shows a series of operation | movement of the ultrasonic diagnosing device which concerns on 3rd Embodiment of this invention. It is a figure which shows the Doppler spectrum in the case of FIG. It is a block diagram which shows the structure of the ultrasonic Doppler diagnostic apparatus which concerns on a prior art example. It is a figure which shows the timing chart of the ultrasonic Doppler diagnostic apparatus which concerns on a prior art example. It is a figure which shows the frequency spectrum pattern of the ultrasonic Doppler diagnostic apparatus which concerns on a prior art example.

[First Embodiment]
(Constitution)
An ultrasonic diagnostic apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

  1 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus, FIG. 2 is a diagram showing the operation of the gain adjustment switch, FIG. 3 is a diagram showing the operation of the DR switch, and FIG. 4 is a Doppler spectrum when the S / N is bad. FIG. 5A is a diagram showing the Doppler spectrum when the gain adjustment switch setting is increased in the case as shown in FIG. 4, and FIG. 5B is the case shown in FIG. FIG. 6 is a diagram showing a series of operations of the ultrasonic diagnostic apparatus.

  As shown in FIG. 1, the ultrasonic diagnostic apparatus according to the first embodiment includes an electronic scanning ultrasonic probe (hereinafter simply referred to as a probe) 11 and an electronic scanning unit 12 connected to the probe 11. ing.

  The electronic scanning unit 12 includes a reference signal generator 20 that generates a reference clock, a delay line 21 that receives the reference clock and generates a delay drive signal (also used as a delay during reception described later), and the delay line 21. And a pulsar 22 for exciting the array-type piezoelectric vibrator group of the probe 11 in response to the delayed drive signal. The electronic scanning unit 12 also includes a receiving system circuit. That is, the preamplifier 23 connected to the probe 11, the delay line 21 that delays the output signal of the preamplifier 23, the adder 24 that adds the delay signal of the delay line 21, and the adder 24 And a detector 25 for subjecting the output signal to logarithmic amplification and envelope detection. The delay line 21 and the adder 24 perform phasing addition of the received echo signals, and are thus subjected to electronic scanning.

  The output signal of the detector 25 is supplied to a DSC (digital scan converter) 30 as an image signal of a B-mode tomogram, and the DSC 30 converts the signal from ultrasonic scanning to standard TV scanning. The conversion signal of the DSC 30 is sent to the display unit (CRT) 32 via the D / A converter 31.

  The output of the adder 24 is also given to the low-pass filter 43 via the phase detection mixer 41 of the extraction means 40. The output of the reference signal generator 20 is directly applied to one channel of the mixer 41 and is connected to the other channel of the mixer 41 via a 90-degree phase shifter 42. For this reason, the received echo signal subjected to phasing addition in the electronic scanning unit 12 is added to the mixer 41, and the reference signal f0 from the reference signal generator 20 and the reference signal f0 having a phase difference of 90 degrees are supplied to the mixer 41. Each is added to two channels. As a result, the mixer 41 outputs the signal of the Doppler shift frequency fd and the signal “2f0 + fd” to the low-pass filter 43. In this low-pass filter 43, the high frequency component of the mixed signal from the mixer 41 is removed, and only the signal of the Doppler shift frequency fd is obtained. The signal of the Doppler shift frequency fd is a phase detection output for calculating blood flow information, and is output to the next stage Doppler spectrum calculation unit 50.

  The Doppler spectrum calculation unit 50 includes a range gate circuit 60 that outputs a sampling pulse, a sample and hold circuit 61 that inputs the sampling pulse, a bandpass filter 62 that filters the output of the sample and hold circuit 61, and the bandpass A frequency analyzer (FFT) 63 for frequency analysis of the output of the filter 62, adjustment means 64 for changing and adjusting the output of the frequency analyzer 63 and converting the output into a display signal, and an output terminal of the adjustment means 64 to the DSC 30 It is connected.

  The sample hold circuit 61 attempts to extract a Doppler signal only for blood flow at a desired depth in the living body, and the phase detection output signal of the low-pass filter 43 is an input signal to the sample hold circuit 61.

  The range gate circuit 60 has a circuit configuration in which a delay time can be arbitrarily set based on a range gate position signal given from an operation unit 82 to be described later. Both the probe 11 and a desired range gate (sampling point and sampling volume) are set. A sampling pulse having a set width is supplied to the sample hold circuit 61 while being delayed from the rate pulse by a time corresponding to the time the ultrasonic signal reciprocates between the position and the position. Thereby, the sample hold circuit 61 samples and holds the phase detection output signal from the low pass filter 43 with the sampling pulse. The sample-and-hold phase detection signal then passes through the band-pass filter 62, and the band-pass filter 62 causes harmonic components generated by sampling in the sample-and-hold circuit 61, fixed reflection signals from the blood vessel wall, and the like. The component corresponding to the Doppler shift frequency due to relatively slow motion is removed, and only the Doppler signal due to blood flow is extracted.

  The frequency analyzer 63 has a fast Fourier transform circuit, performs frequency analysis of the Doppler shift frequency input from the bandpass filter 62, and the analysis result, that is, the Doppler spectrum (frequency spectrum pattern) is passed through the adjustment means 64. Output to the DSC 30. As a result, the Doppler spectrum is divided and displayed on the display unit 32 in parallel with the B-mode tomogram.

  The adjusting means 64 changes the intensity of the Doppler spectrum in a partial range excluding a partial range having a smaller Doppler spectrum intensity. Here, the partial range is a range where the intensity of the Doppler spectrum is smaller than a predetermined threshold, and the partial range is a range where the intensity is larger than the predetermined threshold. The threshold value is, for example, the maximum value of the noise region included in the Doppler spectrum. The adjustment unit 64 includes a correction unit 65, a selection unit 66, an amplification unit 67, a storage unit 68, and a control unit 69.

  When the intensity of the Doppler spectrum (also referred to as “amplitude” or “magnitude”) is changed, the correction unit 65 sets the Doppler spectrum having substantially the same intensity as the predetermined threshold to the predetermined first target value. If not, the intensity of the Doppler spectrum is changed until the Doppler spectrum having the same intensity as the threshold reaches the first target value.

  The selection means 66 selects a range that is larger than a predetermined threshold and sets it as the Doppler spectrum of the partial range. The amplifying unit 67 amplifies the Doppler spectrum of the selected partial range with a predetermined gain.

  The storage means 68 stores a conversion table called a map for rewriting the threshold, the first target value, and the Doppler spectrum intensity to display brightness and tone. In addition to the linear shape, the storage unit 68 stores various types of conversion tables that suppress, for example, luminance with respect to a small amplitude. The control unit 69 converts the Doppler spectrum of the partial range selected by the selection unit 66 or the Doppler spectrum amplified by the amplification unit 67 into a display signal based on a predetermined conversion table read from the storage unit 68.

  The operation unit 82 that is an operation panel includes a trackball and a keyboard that can be arbitrarily operated by the operator, and outputs the above-described range gate position signal and freeze command signal through the operation of the operation unit 82. The operation unit 82 also has a gain adjustment switch that adjusts the display luminance.

  The controller 90 is for changing the setting value to the adjusting means 64 from the setting value of the gain adjustment switch. The set value of the adjusting unit 64 includes the above threshold value, gain, and conversion table.

  Next, the overall operation of the ultrasonic diagnostic apparatus according to the present embodiment will be described with reference to FIGS. 6A is a Doppler spectrum output from the frequency analyzer (FFT) 63, FIG. 6B is a Doppler spectrum whose intensity is changed, and FIG. 6C is a Doppler spectrum in a partial range amplified with a predetermined gain. FIG.

  When the ultrasonic diagnostic apparatus is activated, the electronic scanning unit 12 excites the probe 11 by the rate pulse output from the reference signal generator 20 and transmits the ultrasonic signal into the subject. This ultrasonic signal is reflected by each part of the subject and received by the probe 11 again. The probe 11 converts the signal into an electrical signal corresponding to the ultrasonic echo signal, receives the receiving focus by the adder 24 of the electronic scanning unit 12, and outputs one of the received signals of the designated raster address to the detector 25. Given, logarithmic amplification processing and envelope detection processing, detection and conversion to an image signal of a specified raster address. An image signal forming this B-mode tomographic image is supplied to the DSC 30.

  One of the received signals output from the adder 24 of the electronic scanning unit 12 is phase-detected by the mixer 41 to obtain a signal having a Doppler shift frequency fd and a frequency (2f0 + fd) component. As a result, the high frequency component is removed and only the signal of the Doppler shift frequency fd is obtained. The phase detection output signal for blood flow information calculation is output to the Doppler spectrum calculation unit 50, and the sample hold circuit 61 extracts a signal only at a position where the blood flow in the living body flows, and performs fast Fourier transform. By doing so, frequency analysis is performed in real time.

  In the Doppler spectrum calculation unit 50, the delay time of the range gate circuit 60 can be arbitrarily set. This is done by delaying the reciprocating time from the probe 11 to the sampling point position (range gate position) and giving a sampling pulse having a width corresponding to the set length to the sample hold circuit 61, which is designated by the operator. The Doppler signal at the position of the range gate is obtained.

  The Doppler spectrum obtained by performing the fast Fourier transform in this way is supplied to the DSC 30, and the Doppler spectrum data together with the B-mode image data is synthesized and converted into an image of a standard TV scanning system, and the D / A converter 31 is used. Via the display unit 32. As a result, the display unit 32 displays, for example, a B-mode tomographic image and a Doppler spectrum of the diagnostic site in a divided manner.

  First, the operation principle of the gain adjustment switch and the DR switch will be described. The operation unit 82 is provided with a gain adjustment switch for adjusting a gain. In response to an instruction from the controller 90 by operating the gain adjustment switch, the amplifying means 67 amplifies with a predetermined gain. Here, the amplification means 67 corresponds to a gain adjustment circuit.

  During inspection, the operator adjusts the gain (brightness) of the Doppler spectrum by adjusting the gain adjustment switch so that the Doppler spectrum display is easy to see. As shown in FIG. 2, when the value of the gain adjustment switch is increased, the Doppler spectrum is displayed brighter, and when the value of the gain adjustment switch is decreased, the Doppler spectrum is displayed darker.

  The operation unit 82 is provided with a DR switch (dynamic range adjustment switch) for adjusting the display dynamic range. Upon receiving an instruction from the controller 90 by the operation of the DR switch, the selection unit 66 selects the Doppler spectrum intensity range (displayable signal range), and the amplification unit 67 amplifies the selected range with a predetermined gain. To do. Alternatively, the control unit 69 reads out a predetermined conversion table from the storage unit 68 to correspond to the selected range. The selection means 66 to control means 69 correspond to a dynamic range adjustment circuit (DR adjustment circuit).

  The operator adjusts the DR switch to make the Doppler spectrum display easier to see. As shown in FIG. 3, when the value of the DR switch is increased, the luminances of different input signals are displayed with different luminances. However, when the value of the DR switch is decreased, the overall luminance becomes brighter and exceeds a certain level. It is displayed in a state where the signal intensity is saturated (same luminance).

  When the S / N of the Doppler spectrum is good, it is possible to make the Doppler spectrum display relatively easy to see with any switch, but it is difficult when the S / N is bad as shown in FIG. When the gain is increased as shown in FIG. 5 (a), the brightness of the entire display increases, so that the visibility of the boundary between the signal and noise is not greatly improved, and the value of the DR switch as shown in FIG. 5 (b). It is the same even if the value is reduced.

(Operation)
Next, a series of operations of the adjusting unit 64 when the setting value of the controller 90 is changed from small to large by the operation of the gain adjustment switch of the operation unit 82 will be described with reference to FIG. FIG. 7 is a flowchart showing a series of operations of the adjusting means. Here, the change of the set value from small to large means to increase the gain by the amplification means 67.

  When the setting value of the controller 90 is changed from small to large (step S101; Y), when the noise level does not reach the first target value (step S102; N), the amplifying unit 67 has the noise level of the first level. Until the first target value is reached, the intensity of the Doppler spectrum is changed (change step; S103). The changing step is shown in FIGS. 6 (a) to 6 (b). Here, the first target value is a level at which a noise signal is slightly visible on the display, for example. The maximum value of the noise signal is indicated by a threshold value A1 in FIG. The threshold value A1 is determined in advance and stored in the storage unit 68 as described above.

  Further, when receiving a change from a small setting value to a large setting value of the controller 90, the selection unit 66 selects only a partial range Doppler spectrum (a portion corresponding to a signal having a noise level or higher) (selection step; S104). If the noise level has reached the first target value from the beginning (step S102; Y), the selection step is performed without going through the changing step.

  Next, the control means 69 adjusts the dynamic range adapted to the Doppler spectrum of the selected partial range. The changing step is shown in FIGS. 6 (b) to 6 (c). At this time, the control means 69 changes the dynamic range corresponding to the change of the set value by the operation of the gain adjustment switch.

  The display control means (not shown) displays the changed Doppler spectrum on the display unit 32 with the luminance based on the intensity (display step; S105). Thereby, the Doppler spectrum (blood flow signal) in the partial range can be displayed with a more appropriate display luminance. FIG. 6 shows the noise level (first target value) displayed with the luminance value 0 and the maximum value of the Doppler spectrum displayed with the luminance value 255. The luminance value of the noise level (first target value) may be set so that the noise signal can be seen slightly. By making the noise signal slightly visible, it becomes possible to reliably include a small blood flow signal displayed on the display unit 32. Note that when the set value of the controller 90 is not changed from small to large (step S101; N), the Doppler spectrum is displayed with luminance based on the intensity (S105).

  With the above mechanism, as shown in FIG. 10, even when the S / N is bad, the luminance difference between the signal portion and the noise portion is large only by changing the gain adjustment switch. An easy-to-view image can be provided.

  An ON / OFF switch for this function may be provided. Alternatively, the Doppler spectrum may be observed for a certain period of time, the highest intensity signal in the spectrum may be determined as a blood flow signal, and this function may be operated only when the S / N is below a certain threshold.

[Second Embodiment]
Next, an ultrasonic diagnostic apparatus according to the second embodiment of the present invention will be described with reference to FIG. In the first embodiment, the adjustment unit 64 changes the intensity and dynamic range of the Doppler spectrum in response to the change of the setting value of the controller 90 from small to large by the operation of the gain adjustment switch of the operation unit 82. The second embodiment is different from the first embodiment in that the adjusting means 64 automatically changes the intensity and dynamic range of the Doppler spectrum regardless of the operation of the gain adjustment switch. The other configuration is basically the same as the configuration of the first embodiment.

  Hereinafter, a series of operations of the adjusting unit 64 when an instruction from the controller 90 is received by pressing the display gain automatic adjustment switch of the operation unit 82 will be described.

  When receiving an instruction from the controller 90, if the noise level does not reach the first target value, the correcting means 65 changes the intensity of the Doppler spectrum until the noise level reaches the first target value (change step). The changing steps are shown in FIGS. 8A to 8B.

  Next, the selection unit 66 selects only the Doppler spectrum of the partial range (the portion corresponding to the signal having a noise level or higher) (selection step). If the noise level has reached the first target value from the beginning, the selection step is performed without going through the change step.

  Next, the amplifying means 67 is based on the highest intensity signal A2 in the Doppler spectrum observed for a certain time, so that the highest intensity signal A2 becomes the determined second target value. Change the dynamic range. The maximum intensity signal is indicated by A2 in FIG. The dynamic change step is shown in FIGS. 8B to 8C. The second target value and the maximum intensity signal A2 are determined in advance and stored in the storage unit 68.

  According to the ultrasonic diagnostic apparatus according to the second embodiment, it is possible to display the Doppler spectrum in the partial range with an appropriate display brightness by pressing the display gain automatic adjustment switch, further reducing the burden on the operator. This makes it possible to further reduce the diagnosis time.

[Third Embodiment]
Next, an ultrasonic diagnostic apparatus according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a diagram showing a series of operations of the ultrasonic diagnostic apparatus, and FIG. 10 is a diagram showing a Doppler spectrum.

  As shown in FIG. 3, in the conventional DR adjustment circuit, when the value of the DR switch is increased, the luminance of different input signals is displayed with different luminance. However, when the value of the DR switch is decreased, the overall luminance is increased. It becomes brighter and is displayed in a state (same luminance) in which the signal intensity above a certain level is saturated.

  In the conventional DR adjustment circuit, the input signal 0 corresponds to the output luminance 0, and the control unit 69 uses a predetermined conversion table according to the DR setting (the size of the range selected by the selection unit 66). Thus, the slope (gain) of the input / output characteristic line is changed, and the display luminance of the noise also changes greatly according to the DR setting.

  In the third embodiment, the control means 69 performs control so that the threshold value A1 becomes the center value of the slope of the input / output characteristic straight line (dynamic range characteristic). By performing such control, the signal of the threshold A1 is displayed with the same luminance regardless of the DR setting.

  Furthermore, control is performed so that the signal intensity at the noise level always has the same output luminance. Even if the DR setting value on the operation unit 82 is the same, even when the signal strength of the noise level changes depending on the probe to be used, transmission / reception conditions, and gain adjustment switch setting value, control is performed so that the same output luminance is obtained. Thus, the threshold value A1 (the center value of the slope of the input / output characteristic line) is changed. Thereby, even when the DR setting value is changed, the display luminance of noise does not change, and an easy-to-see spectrum can be displayed.

A1 threshold A2 highest intensity signal 11 ultrasonic probe 12 electronic scanning unit 20 reference signal generator 21 delay line 22 pulser 23 preamplifier 24 adder 25 detector 30 DSC 31 D / A converter 32 display unit (display unit)
40 Extraction means 41 Mixer 42 90 degree phase shifter 43 Low pass filter 50 Doppler spectrum calculation unit 60 Range gate circuit
61 Sample hold circuit 62 Band pass filter
63 Frequency analyzer (FFT)
64 Adjustment means 65 Correction means 66 Selection means 67 Amplification means
68 storage means 69 control means 82 operation unit (operation panel)
90 controller

Claims (7)

Transmitting and receiving means for transmitting and receiving an ultrasonic beam to and from a diagnostic site including a moving body in a subject;
Extraction means for extracting a Doppler signal caused by the moving body at a desired range gate position from the received signal obtained by the transmission / reception means;
Frequency analysis means for calculating a Doppler spectrum from the extracted Doppler signal;
Adjusting means for changing the intensity of the Doppler spectrum in a partial range excluding a partial range of the calculated smaller intensity of the Doppler spectrum;
Display control means for causing the display unit to display the Doppler spectrum changed by the adjustment means at a luminance based on the intensity;
An ultrasonic diagnostic apparatus characterized by comprising:   The adjusting means excludes a Doppler spectrum having an intensity lower than a predetermined threshold as the partial range, and when a Doppler spectrum having substantially the same intensity as the threshold does not reach a predetermined first target value, 2. The ultrasonic diagnostic apparatus according to claim 1, further comprising correction means for changing the intensity of the Doppler spectrum so that Doppler spectra having substantially the same intensity reach the first target value.   The adjustment unit further includes a selection unit that selects a range larger than the threshold and sets the Doppler spectrum of the partial range, and an amplification unit that amplifies the Doppler spectrum of the selected partial range with a predetermined gain. The ultrasonic diagnostic apparatus according to claim 1 or claim 2, wherein   The amplification means amplifies the Doppler spectrum of the selected partial range so that the maximum Doppler spectrum in the partial range becomes a predetermined second target value. An ultrasonic diagnostic apparatus according to 1.   The adjusting means selects a predetermined intensity range centered on the threshold value, and selects the selected range as a Doppler spectrum of the partial range within the selected range, and the selection The ultrasonic diagnostic apparatus according to claim 1, further comprising an amplifying unit that amplifies the Doppler spectrum in the range with a predetermined gain.   The display control means takes a time axis on one of the horizontal axis and the vertical axis and a Doppler shift frequency on the other side of the horizontal axis or the vertical axis, and the strength of the Doppler shift frequency that changes over time. The ultrasonic diagnostic apparatus according to claim 1, wherein the Doppler spectrum is displayed on the display unit with a luminance corresponding to the frequency. A transmission / reception step of transmitting / receiving an ultrasonic beam to / from a diagnostic site including a moving body in a subject;
An extraction step of extracting a Doppler signal caused by the moving body at a desired range gate position from the reception signal obtained by the transmission / reception step;
A calculation step of calculating a Doppler spectrum from the extracted Doppler signal;
When receiving an instruction by operating the operation unit, the calculated Doppler spectrum is amplified by a predetermined gain, and a Doppler spectrum having substantially the same intensity as a predetermined threshold reaches a predetermined first target value. A step of changing the intensity of the Doppler spectrum so that a Doppler spectrum having substantially the same intensity as the threshold reaches the first target value,
After the changing step, further, a selection step for selecting a range larger than the threshold and setting it as a Doppler spectrum of a partial range;
An amplification step of amplifying the selected Doppler spectrum of the partial range with a predetermined gain;
Displaying the Doppler spectrum of the partial range amplified by the amplification step on a display unit with luminance based on the intensity; and
An image display method in an ultrasonic diagnostic apparatus characterized by comprising: