JPH11123191A - Ultrasonic diagnostic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve spatial resolution by generating a second reception signal along a prescribed scanning line from a first reception signal along plural different scanning lines obtained by a transmission/reception means so as to output an image. SOLUTION: Based on an inputted scanning line switching signal and a control clock, a counter 2050 prepares three scanning lines L0 to L2, for example. Their scanning line data is written in each scanning line data FIFO 2051 to 2053 and sent to a displacement arithmetic part 2054 and a second order differential arithmetic part 2055 to obtain the displacement (d) of a target. In addition, target intensity is obtained. Then, a noticing scanning line such as displacement data (d) on L1 is inputted to a high resolution making differential luminance arithmetic part 2064 to execute prescribed arithmetic processing here to generate new scanning line data expressing a received ultrasonic beam with a small beam diameter. Thereby, small spatial separation is executed to improve the spatial resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic wave for receiving an ultrasonic wave transmitted into a subject, reflected from the subject and returned, obtains a received signal, and generates an image based on the received signal. It relates to a diagnostic device.

[0002]

2. Description of the Related Art An ultrasonic wave which transmits an ultrasonic wave to a subject, particularly a human body, receives an ultrasonic wave reflected and returned from each tissue in the subject, and generates an image of the inside of the subject based on the received signal. 2. Description of the Related Art A diagnostic device has been conventionally used for diagnosing a disease inside a subject. FIG. 15 is a schematic diagram illustrating a state in which an image of a target (ultrasonic reflector) is obtained when a target (ultrasonic reflector) exists at a certain point in the subject using the ultrasonic diagnostic apparatus.

As shown in FIG. 15A, this ultrasonic diagnostic apparatus is provided with a number of ultrasonic transducers 21 arranged in a predetermined direction (horizontal direction in FIG. 15). The ultrasonic transducer 21 is applied to the body surface of the subject, and at one ultrasonic transmission / reception timing, a plurality of ultrasonic vibrations included in a certain opening 22 set for the ultrasonic transmission / reception at that timing. By exciting the probe with an electric pulse, an ultrasonic pulse is transmitted toward the inside of the subject. In transmitting the ultrasonic waves, the excitation intensity for exciting each of the plurality of ultrasonic transducers included in the opening 22 is adjusted, and the excitation intensity for exciting each of the plurality of ultrasonic transducers is changed to the ultrasonic oscillator included in the opening 22. Is adjusted in accordance with a predetermined weighting function 23 using the position of the array (array order) as a variable, thereby forming a directional ultrasonic beam 24 in the subject.

[0004] The ultrasonic wave reflected back in the subject is
Each of the plurality of ultrasonic transducers constituting the aperture 22 is received, and each of the received signals is amplified according to the weighting function 23, and the ultrasonic reflected signal in the direction along the ultrasonic beam 24 extending into the subject is obtained. As emphasized (this is referred to herein as forming a “received ultrasound beam”, whereas an ultrasound beam transmitted into the subject is referred to as a “transmitted ultrasound beam”).
They are relatively delayed and added together. Here, the process of adding each other with a relatively delay is referred to as “phasing addition”.
Called.

The process of transmitting and receiving ultrasonic waves is repeated while sequentially moving the openings 22 in the direction in which the ultrasonic transducers 21 are arranged. The process of repeating transmission and reception of ultrasonic waves while sequentially moving the opening 22 is referred to as “scanning”. Here,
For simplicity, the transmission aperture and the reception aperture, the transmission weighting function and the reception weighting function, and the transmission ultrasonic beam and the reception ultrasonic beam have been described without distinction, but they are different between the transmission side and the reception side. Alternatively, the settings may be appropriately set on the transmission side and the reception side.

[0006] By displaying the intensities of a plurality of received signals representing a plurality of received ultrasonic beams obtained in the above scanning process as luminance, an image of the inside of the subject can be obtained. Here, the case where only one target exists in the subject is considered, and the ultrasonic beam 24
Since both the transmission ultrasonic beam and the reception ultrasonic beam have directivity, the intensity of the reception signal for each aperture set in the scanning process is as shown in FIG. Each value is shown. Here, those signal intensity distributions are referred to as “beam profiles”.

FIG. 15C shows an image (target image) in which a received signal having such a signal intensity distribution is represented by luminance.

[0008]

The smaller the size of the target image, the better the resolution of the ultrasonic diagnostic apparatus. However, usually, the size of the target image is considerably larger than the size of the target 25 itself. It is widely spread. Conventionally, the intensity distribution (beam profile) of the received signal that determines the size of the target image is determined by the size of the aperture 22, the weighting function 23, and the wavelength λ of the transmitted / received ultrasonic wave. Although some efforts have been made to optimize the settings, there is a limit to further improvement in resolution.

Conventionally, when the position of the target 25 is determined, the position of the target 25 in the array direction of the ultrasonic transducers 21 can be determined by scanning the subject and determining the peak position of the received signal intensity. However, the intervals of the openings sequentially set at the time of scanning are coarse.
If the openings are set only in the horizontal direction of 5 (a), the true peak position cannot be detected,
As a result, the detection accuracy of the target position is reduced. On the other hand, if the aperture is finely set in order to obtain sufficient target position detection accuracy, it is necessary to perform ultrasonic transmission and reception a number of times corresponding to the number of the finely set apertures, and scan the subject once. It takes a long time to perform the operation, and there is a problem that the frame rate is reduced.

[0010] The same phenomenon as described above also occurs in one ultrasonic beam, that is, in the direction in which the ultrasonic beam extends (the depth direction in the subject). FIG. 16 is a schematic diagram showing a signal waveform of an ultrasonic wave reflected and returned by a target in a subject and a process of processing the signal. In the subject, for example, a burst wave-like ultrasonic wave similar to that shown in FIG. 16A is transmitted, and the burst wave-like ultrasonic wave is reflected and returned inside the subject. It is assumed that there is only one target, and the ultrasonic wave whose transmitted burst wave is reflected by the single target and returns to the ultrasonic transducer also becomes a burst wave. Here, it is assumed that FIG. 16A shows the ultrasonic burst wave reflected and returned in this manner, and the ultrasonic wave having the waveform shown in FIG. 16A is picked up by the ultrasonic transducer. The signal picked up in this manner is logarithmically amplified and subjected to envelope detection to obtain an envelope signal shown in FIG. Next, this envelope signal is quantized by A / D conversion. Therefore, a signal obtained from only one target in the subject has a certain pulse width in the depth direction inside the subject, and the resolution in the depth direction is limited to a resolution corresponding to the pulse width. Will be done.

Conventionally, in order to improve the resolution in the depth direction, a high frequency ultrasonic wave has been devised. However, for example, a high frequency ultrasonic wave is greatly attenuated and a deep region in a subject is deep. And the resolution in the depth direction is limited.
When the position of the target in the depth direction is obtained, the position of the target in the depth direction can be obtained by obtaining the peak position of the received signal strength (the position of the vertex of the envelope signal). If the sampling interval of the / D conversion is coarse, the true peak position of the burst wave cannot be detected, resulting in a decrease in the target position detection accuracy. On the other hand, if the sampling interval is set sufficiently small using a high-speed A / D converter in order to obtain sufficient target position detection accuracy, the data amount will increase, and the high-speed A / D converter and data An increase in cost due to an increase in memory capacity accompanying the increase is inevitable.

The present invention has been made in view of the above circumstances, and has as its object to provide an ultrasonic diagnostic apparatus capable of improving the spatial resolution as compared with the related art.

[0013]

Means for Solving the Problems A first ultrasonic diagnostic apparatus of the ultrasonic diagnostic apparatus of the present invention, which achieves the above object, comprises:
A first ultrasonic wave is received along the predetermined scanning line extending into the object after receiving the ultrasonic wave transmitted into the object and reflected in the object.
Transmitting and receiving means for sequentially repeating a process of generating a first received signal representing the received ultrasonic beam for a plurality of different scanning lines, and a plurality of first receiving means along the different plurality of scanning lines obtained by the transmitting and receiving means An operation of generating a second reception signal representing a second reception ultrasonic beam along a predetermined scanning line based on a plurality of first reception signals representing an ultrasonic beam is executed for a plurality of different scanning lines. It is characterized by comprising a calculating means and an image output means for outputting an image based on the second received signal obtained by the calculating means.

Here, the calculating means may generate the second received signal by executing a calculation including a calculation for determining the position of the ultrasonic reflection source in the subject.
In this case, the calculating means is configured to determine the ultrasonic reflection source in the subject based on two first reception signals representing two reception ultrasonic beams along two scanning lines sandwiching the predetermined scanning line. By performing an operation including an operation of calculating a distance from the predetermined scanning line, the second operation along the predetermined scanning line is performed.
It is preferable to generate a second reception signal representing the reception ultrasonic beam of the above.

[0015] Further, the calculating means generates a second reception signal representing a second reception ultrasonic beam having a beam diameter smaller than the beam diameter of the first reception ultrasonic beam represented by the first reception signal. It is preferable to execute the operation to be generated. When generating a second reception signal representing a second ultrasonic beam having a beam diameter smaller than the beam diameter of the first reception ultrasonic beam, the calculating means includes:
Based on a change in a first received signal in a vicinity of the predetermined scan line on a predetermined traversing line that crosses a plurality of scan lines including the predetermined scan line, the predetermined scan line and the predetermined scan line It is determined whether or not to adopt a new reception signal for the intersection of at least one of the adjacent scanning lines in place of the second reception signal for the intersection of the predetermined traverse line and the new intersection signal. It is preferable that a new reception signal is employed for the intersection when the condition for employing the reception signal is satisfied, instead of the second reception signal, and in this case, the arithmetic means A differential value of the first received signal in a direction along the predetermined transverse line at an intersection of the predetermined transverse line and the predetermined scan line is obtained, and a magnitude comparison between the differential value and a predetermined threshold value is performed. By doing It is also a preferable embodiment that it is determined whether or not to adopt a new received signal at the intersection of the predetermined intersection line with the intersection of the at least one scanning line instead of the second received signal. .

A second ultrasonic diagnostic apparatus among the ultrasonic diagnostic apparatuses of the present invention that achieves the above object is an ultrasonic diagnostic apparatus that transmits a burst wave into the subject and reflects back in the subject. Transmitting and receiving means for generating a first reception signal representing a first reception ultrasonic beam along a predetermined scanning line extending into the subject, and receiving a first reception signal along the predetermined scanning line obtained by the transmission / reception means. Computing means for performing an operation of generating a second reception signal representing a second reception ultrasonic beam along a predetermined scanning line based on a first reception signal representing one reception ultrasonic beam; and computation means And an image output means for outputting an image based on the second received signal obtained in (1).

Here, the calculation means executes the calculation including the calculation of the depth position of the ultrasonic reflection source in the subject in the direction along the predetermined scanning line, thereby converting the second reception signal. May be generated, in which case, the calculating means interposes a predetermined point on a predetermined scanning line, based on first reception signals related to two points on the predetermined scanning line,
By performing an operation including an operation for obtaining a distance from the predetermined point in a direction along the predetermined scanning line of the ultrasonic reflection source in the subject, a second reception ultrasonic wave along the predetermined scanning line is performed. It is preferable to generate a second reception signal representing a sound beam.

The calculating means may include a second received ultrasonic beam having a higher resolution than a first received ultrasonic beam represented by the first received signal in a direction along the scanning line. It is preferable to execute an operation for generating the second received signal. When a second reception signal representing a second reception ultrasonic beam having a higher resolution than the resolution of the first reception ultrasonic beam in the direction along the scanning line is generated, the arithmetic unit performs a predetermined scan. Based on a change in the first received signal in the vicinity of the predetermined point on the line, the second received signal relating to at least one of the points near the predetermined point on the predetermined scanning line, including the predetermined point, Instead, it is determined whether or not a new reception signal is to be adopted for that point, and when a condition for employing the new reception signal is satisfied, a new reception is made for that point in place of the second reception signal for that point. Preferably, a signal is adopted, and in this case, the arithmetic unit includes:
The first received signal, the differential value in the direction along the predetermined scanning line at the predetermined point is obtained, and by comparing the differential value with a predetermined threshold value, the predetermined point is included. It is also preferable to determine whether or not to adopt a new reception signal for the point in place of the second reception signal for at least one of the points near the predetermined point on the predetermined scanning line. It is a form.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION First, an embodiment of an ultrasonic diagnostic apparatus according to the present invention will be described theoretically, and then the configuration of the apparatus will be described. FIG.
FIG. 4 is a schematic diagram of a beam profile of a received ultrasonic beam. Here, a plurality of scanning lines..., L0, L1, L
, L0, L1, L2,..., H, a target, and a scanning line L1 of interest here.
And the actual beam profile is a Gaussian function

[0020]

(Equation 1)

[0021] Here, x represents the distance in the arrangement direction of the scanning lines (the left-right direction in FIG. 1) when the position of the target is set as the origin. If the intensity of the target is P, the scanning line L caused by the target is
The amplitudes A, C, and B of the received signals for 0, L1, and L2 are
Each,

[0022]

(Equation 2)

## EQU1 ## Taking the ratio of the equations (2) and (4), B / A = e ^4adh (5) Taking the logarithm of each side of the equation (5), ln (B) -ln (A) = 4ahd (6) Therefore, d = {ln (B) -ln (A)} / 4ah (7) Becomes Here, a is a value that defines an actual beam profile and is known, as shown in Expression (1), and h is
Is the pitch between scan lines, which is also known. Therefore, this equation (7) is obtained by calculating the difference between the logarithmically detected received signals for the scanning lines L0 and L2.
This indicates that the displacement d of the target can be obtained.

The target strength P is calculated by using the target displacement d obtained as described above.

[0025]

(Equation 3)

It is determined by any one of the following equations.
Hereinafter, equation (10) is used. Thus, (7)
When the displacement d of the target is obtained from the expression and the intensity P of the target is obtained from the expression (10), the scanning line L1 of interest in accordance with the new narrow beam profile g ₁ (x) is obtained.
The received signal for

[0027]

(Equation 4)

Given by If an attempt is made to obtain a beam profile g ₁ (x) having a beam width 1 / k times the resolution of the actual beam profile f (x) (k times the resolution), equation (11) gives

[0029]

(Equation 5)

## EQU1 ## Taking the logarithm of each side of the expression (12), ln (C _c ) = In (C) −a (k ² −1) d ² (13) That is, by subtracting a (k ² −1) d ² from the logarithmically detected amplitude ln (C) of the scan line L1 of interest, the amplitude ln (C _c ) whose resolution has been increased k-fold.
Is required.

By performing the above calculation, a beam profile smaller than the beam profile of the actual received ultrasonic beam (the first received ultrasonic beam in the first ultrasonic diagnostic apparatus of the present invention) is obtained. A received ultrasonic beam (an example of a second received ultrasonic beam in the first ultrasonic diagnostic apparatus of the present invention) can be generated. In the above description, the two scanning lines L0 and L2 sandwiching the target scanning line L1 are described.
The distance d between the target scanning line (L1) and the target was obtained based on the signal of the above. However, in obtaining the distance d between the target scanning line L1 and the target, the target scanning line L1 was not necessarily used. It is not necessary to use the signals of the two scanning lines sandwiched therebetween, and the distance between any one of the scanning lines and the target may be determined based on the signal of any one of the plurality of scanning lines.

In the above description, the beam profile is assumed to follow the Gaussian function. However, another function may be adopted as a function for defining the beam profile. The above is the direction traversing the ultrasonic beam (FIG. 15).
Although the description is related to (left-right direction in FIG. 15A), the same holds true for the direction in which one ultrasonic beam extends (vertical direction in FIG. 15A, depth direction in the subject).
Hereinafter, the direction in which the one ultrasonic beam extends will be described.

FIG. 2 shows a beam profile in the depth direction of an ultrasonic wave reflected and returned from a certain point in the subject (burst wave profile (see FIG. 16)).
FIG. As described with reference to FIG. 16, the beam profile (burst wave profile) transmits the burst wave into the subject and reflects the burst wave returned by reflecting at a certain point in the subject. The signal is obtained by receiving, pair wave amplification, and envelope detection, and further converted into discrete signals at each point (each depth position) by A / D conversion.

Here, it is assumed that sampling is performed by A / D conversion at each of the times t0, t1, t2,..., The pitch of the times t0, t1, t2,. The distance from the sampling point t1 is defined as r, and the beam profile in the depth direction (burst wave profile) is represented by a Gaussian function.

[0035]

(Equation 6)

The following is assumed. Here, z represents the distance in the depth direction (the left-right direction in FIG. 2) when the position of the target is set as the origin. The ultrasonic wave travels slowly inside the subject compared to the speed of signal processing, and each sampling time t0, t1, t2,... Corresponds to each depth position in the subject.

Here, assuming that the intensity of the target is P,
Times t0, t1, t2,... Resulting from the target.
The received signal amplitudes D, E, and F are

[0038]

(Equation 7)

## EQU1 ## Taking the ratio of equations (14) and (16),

[0040]

(Equation 8)

## EQU1 ## Taking the logarithm of each side of the equation (17), ln (F) −ln (D) = 4brΔ (18) Therefore, r = {ln (F) −ln (D)} / 4bΔ (19) Becomes Here, b is a value that defines the actual profile of the burst wave in the depth direction of the ultrasonic beam as shown in Expression (13) and is known, and Δ is the depth direction corresponding to the sampling interval. Which is also known. Therefore, this equation (19) can be expressed as follows:
It shows that the displacement r in the depth direction of the target can be obtained by obtaining the difference between the logarithmically detected received signals with respect to 0 and t2. .

The target strength P is calculated by using the target displacement r obtained as described above.

[0043]

(Equation 9)

Which is obtained by any one of the following expressions:
Hereinafter, equation (22) is used. In this way, (1
The displacement r in the depth direction of the target is obtained from the equation 9), and
When the target intensity P is obtained from the equation (22), the received signal related to the sampling point t1 according to a new beam profile (burst wave with a narrow pulse width) g ₂ (z) in the depth direction becomes

[0045]

(Equation 10)

The pulse width (resolution k times) of 1 / k times the actual profile f ₂ (z) of the burst wave given by
When trying to obtain a burst wave profile g ₂ (z) of the following equation (23),

[0047]

[Equation 11]

Is as follows. (24) Taking the sides s of the logarithm of the equation, the _{ln (F c) = ln (} F) -b (k 2 -1) r 2 ...... (25). That is, by subtracting b (k ² -1) r ² from the amplitude ln (F) of the logarithmic detection for the target sampling point t1, the amplitude ln whose resolution is increased by k times
(F _c ) is required.

By performing the above-described calculation, the pulse width of the pulse wave is larger than that of the burst wave constituting the actual received ultrasonic beam (the first received ultrasonic beam in the second ultrasonic diagnostic apparatus of the present invention). It is possible to generate a received ultrasonic beam (an example of a second received ultrasonic beam in the second ultrasonic diagnostic apparatus of the present invention) constituted by a narrow burst wave.

In the above description, the target sampling point t
The distance r between the target sampling t1 and the target is determined based on the signals of the two sampling points 0 and t2 sandwiching 1.
However, in obtaining the distance r between the target sampling point t1 and the target, it is not always necessary to use the signals of the two sampling points sandwiching the target sampling point t1, and The distance in the depth direction between an arbitrary sampling point and the target may be obtained based on the signal.

In the above description, the burst wave profile has been described as following the Gaussian function.
Another function may be adopted as a function defining the profile of the burst wave. As described above, with respect to the direction traversing the ultrasonic beam (the left-right direction in FIG. 15A), the direction in which the ultrasonic beam extends (the vertical direction in FIG. 15A and the depth direction in the subject) Can also improve the resolution by employing the same principle.

In the above description, each direction has been described independently. However, the calculation may be performed simultaneously in these two directions to increase the resolution in both directions at the same time.
By the way, when a receiving ultrasonic beam having a small beam diameter or a receiving ultrasonic beam having an improved resolution in the depth direction is generated as described above, the resolution is improved, but there is a problem that a so-called black hole is conspicuous.

FIG. 3 is a schematic diagram in which an image including a plurality of scanning lines and a black hole is superimposed, and FIG. 4 is along a transverse line AA ′ extending across the plurality of scanning lines shown in FIG. Scan line data (each scan line and transverse line AA 'of each received signal)
3 is a graph showing scanning line data along one scanning line L shown in FIG. 3 (data at each sampling point of a received signal representing a received ultrasonic beam along the scanning line) shown in FIG. is there.

A black hole refers to a 'black spot' which appears randomly on an image and is caused by interference (speckle interference) between ultrasonic waves reflected and scattered in a subject in a complicated manner. As shown in FIG. 7, the scanning line is substantially circular or elliptical, and in most cases, one scanning line passes through the center of the circle (ellipse), and in the direction along the transverse line AA ′, scanning is performed on both sides of the scanning line. The line passes outside the circle (ellipse). As shown in FIG. 4, the scanning line data at the center of the black hole has a smaller value than the scanning line data on both sides of the black hole and has a valley. Also, the scanning line L
In the case of the direction along, depending on the fineness of the sampling, if sampling is performed at the same fine pitch as the pitch in the direction along the transverse line AA ′ (the pitch of the scanning line), again, in most cases, One sampling point exists at the center of the black hole, and the sampling points on both sides exist outside the circle (ellipse).

FIG. 5 shows scanning line data (referred to as original scanning line data) when a received ultrasonic beam having an actual beam profile is used, and scanning with a beam profile having a narrow beam diameter or a short pulse width. 5 is a graph showing line data (referred to as new scan line data).
In the case of new scanning line data, as shown in FIG. 5, the black hole tends to expand due to the decrease in the beam diameter or the decrease in the pulse width. Black holes are conspicuous, making the image difficult to see.

Therefore, here, the black hole is corrected as follows. FIG. 6 is a graph showing the second derivative of the scanning line data. The position of the black hole is the second derivative of the scan line data at the same depth position of the subject, that is, the second derivative of the scan line data in the direction along the cross-sectional line AA ′ or the scan line L shown in FIG. It can be detected by asking. That is, in the black hole, FIG.
As shown in the above, since the second derivative takes a large positive value, the position of the black hole is detected by setting an appropriate threshold and determining whether or not the second derivative exceeds the threshold. can do. Here, the scanning line is L
0, L1, and L2, and each scanning line L0, L
Scan line data on L1, L2 and L2, respectively.
When the second differential value on the scanning line L1 is represented by L2
+ L0-2L1.

In this manner, a black hole is detected,
On two scanning lines (or two scanning lines) adjacent to the scanning line (or sampling point) where the center of the black hole exists.
If the value of the scanning line data at one sampling point) is corrected so that the luminance of that portion does not decrease significantly, the expansion of the black hole can be prevented. FIG. 7 is an explanatory diagram of a method of correcting scanning line data at both ends of a black hole.

Here, when a black hole is detected as described above, two black scanning lines (or two sampling points) adjacent to the scanning line (or two sampling points) where the center of the black hole is located. As for the scan line data, a new scan line data obtained by an operation for realizing a narrow beam diameter (or a short pulse width) is not used, and a value obtained by subtracting a certain value from the original scan line data is used. . Specifically, the scanning line data indicated by a and b in FIG. 7 is corrected to ac and bc, respectively. By doing so, an extreme decrease in brightness at the end of the black hole can be suppressed. In addition, a value obtained by multiplying the original scanning line data by a positive constant of 1 or less may be used instead of the new scanning line data obtained by the operation for realizing the narrow beam diameter (or the short pulse width). Good. In this case as well, an extreme decrease in luminance at the end of the black hole can be similarly suppressed.

FIG. 8 is an explanatory diagram of another example of the method of correcting the scanning line data at both ends of the black hole. Here, after a black hole is detected in the same manner as above, the scanning line (or sampling point) at the center of the black hole and the adjacent scanning lines (or adjacent sampling points) on both sides of the scanning line (or sampling point) are obtained. The average value of the scanning line data of the scanning lines on both sides of the scanning line (or sampling point) is adopted. Specifically, the scanning line data indicated by b, c, and d in FIG.
/ 2, (b + d) / 2, (c + e) / 2. By performing such correction, not only both ends of the black hole but also the brightness of the center of the black hole can be increased, so that it is possible to provide a more easily viewable image.

The above is the end of the theoretical description of the embodiment of the present invention. Next, the configuration of the device according to the embodiment of the present invention will be described. FIG. 9 is a block diagram showing an embodiment of the ultrasonic diagnostic apparatus of the present invention. First, the outline of the ultrasonic diagnostic apparatus of the present embodiment will be described with reference to this block diagram. Hereinafter, the operation or function of each unit will be described later, and first, the configuration of the ultrasonic diagnostic apparatus will be described.

The main body 10 of the ultrasonic diagnostic apparatus is roughly composed of a control section 100, a signal processing section 200, a digital scan converter section 300, a Doppler processing section 400, a display control section 500, and a biological signal amplifier section 600. ing. The control unit 100 includes a CPU unit 101 and a beam scan control unit 102. The CPU unit 101 includes an operation panel 701, an integrated touch panel 702 and an EL display 703, and a floppy disk device 70.
4 are connected.

Further, the signal processing unit 200
1, reception delay control section 202, beamformer section 20
3. Control interface unit 204, arithmetic unit 2
The control interface unit 204 is connected to the transmission / reception unit 201, the reception delay control unit 202, and the Doppler signal processing unit 206 via a control line 207. Also, the control interface unit 204
And the arithmetic unit 205 are connected by a control line 208. Further, the reception delay control unit 202 and the beamformer unit 2
03 is connected by a control line 209. Signal processing unit 2
The transmitting and receiving unit 201 constituting the ultrasonic probe 2
0 is detachably connected here, up to a maximum of four.

The digital scan converter 3
00 is provided with a black-and-white scan converter 301, a color scan converter 302, and a scroll scan converter 303. Further, the Doppler processing unit 400 includes a pulse / continuous wave Doppler analysis unit 401 and a color Doppler analysis unit 402.

Further, the display control section 500 here
The display control unit 500 includes a printer 705 and a VTR (video tape recorder).
706, observation television monitor 707, and speaker 7
08 is connected. Also, the biological signal amplifier unit 600
Also, like the display control unit 500, it is shown here as one block.
The CG electrode unit 709, the heart sound microphone 710, and the pulse wave transducer 711 are connected.

Further, the ultrasonic diagnostic apparatus is provided with a power supply section 800. The power supply unit 800 is connected to a commercial power supply and supplies necessary power to each unit of the ultrasonic diagnostic apparatus. The main unit 10 has a CPU bus 901. The CPU bus 901 is connected to the CPU 101 and the beam scan control unit 10 that constitute the control unit 100.
2, a control interface unit 204 constituting the signal processing unit 200, a black-and-white scan converter 301 constituting the digital scan converter unit 300,
The color scan converter 302 and the scroll scan converter 303, the pulse / continuous wave Doppler analysis unit 401 and the color Doppler analysis unit 402 included in the Doppler processing unit 400, and the image display unit 500 are connected. The main body 10 is provided with an echo bus 9.
The echo bus 902 supplies image data generated by the arithmetic unit 205 included in the signal processing unit 200 to the digital scan converter unit 300. Further, a pulse / continuous wave Doppler analysis unit 401 and a color Doppler analysis unit 402 constituting the Doppler processing unit 400
Are also supplied to the digital scan converter unit 300 via the echo bus 902. Further, the main body 10 has a video bus 903, and the video bus 903 is used for the black and white scan converter 3 constituting the digital scan converter 300.
01, the video signal generated by one of the color scan converter 302 and the scroll scan converter 303 is transmitted to the display control unit 500.

The operation panel 701 is composed of a keyboard or the like having a number of keys. When the operation panel 701 is operated, the operation information is detected by the CPU section 101, and a command corresponding to the operation information is issued according to the command. And the beam scan control unit 102 and the control interface unit 2
04, the digital scan converter unit 300, the Doppler processing unit 400, or the display control unit 500.

The EL display section 703 has a liquid crystal display screen, and the CPU section 101 also functions as an EL line drawing creation section for creating an EL line drawing to be displayed on the liquid crystal display screen of the EL display section 703. The EL line drawing generated by the CPU unit 101 is displayed on the liquid crystal display screen of the EL display unit 703. A touch panel 702 is provided on the liquid crystal display screen of the EL display unit 703, and when the touch panel 702 is touched with a finger, position information indicating the position touched by the finger on the touch panel 702 is transmitted to the CPU unit 101. . The touch panel 702 and the EL display 7
For example, when the operator instructs the ultrasonic diagnostic apparatus to set a parameter relating to a certain mode by operating the operation panel 701, the CPU 101 displays a list of a large number of parameters to be set for the one mode by the CPU 101.
It is displayed on the L display unit 703, and is configured to easily input various instructions to the ultrasonic diagnostic apparatus, such as setting desired parameters by touching the touch panel 702 with a finger.

The floppy disk device 704 is a device in which a floppy disk (not shown) is removably mounted, and accesses the loaded floppy disk.
01 and instructions given by operating the touch panel 702 are written to the floppy disk loaded in the floppy disk device 704, and resetting to the initial state by turning on the power to the ultrasonic diagnostic apparatus or by operating the operation panel 701 is performed. When instructed, various kinds of instruction information written from the floppy disk loaded in the floppy disk device 704 to the CPU 10
1, the CPU unit 101 sets each unit to an initial state according to the instruction information. This is the operation panel 7 necessary for operating this ultrasonic diagnostic apparatus.
01 and many parameters to be set from the touch panel 702. For example, it is extremely difficult to reset these many parameters every time the power is turned on. For this reason, it is necessary to write the initial state parameters and the like to a floppy disk. When the power is turned on or when resetting to the initial state is instructed, parameters and the like written on the floppy disk are read and each unit is set according to the parameters and the like, so that the setting efficiency of the parameters and the like is improved. It is to make it.

CPU unit 101 constituting control unit 100
Is mainly responsible for the man-machine interface as described above, while the control unit 10
The beam scan control unit 102 constituting 0 is mainly in charge of control that requires real-time properties such as the transmission and reception timing of ultrasonic waves by the ultrasonic diagnostic apparatus. When transmitting and receiving an ultrasonic wave with this ultrasonic diagnostic apparatus, data for controlling each unit constituting the signal processing unit 200 is transmitted from the beam scan control unit 102 to the CPU bus 9.
01, and transmitted to the control interface unit 204 of the signal processing unit 200 via the control line 207. The control interface unit 204 controls the transmission / reception unit 201, the reception delay control unit 202, and the Doppler signal processing unit 206. The control interface unit 204 controls the control line 2
08, the arithmetic unit 205 is controlled, and the reception delay control unit 202 further includes a control interface unit 2
The beam former 203 is controlled via the control line 209 under the control of the controller 04. Details of control of each unit of the signal processing unit 200 will be described later.

The transmitting / receiving unit 201 includes the ultrasonic probe 20
Is connected. The ultrasonic probe includes, for example, a linear scanning ultrasonic probe, a convex scanning ultrasonic probe, a sector scanning ultrasonic probe, and, as a special ultrasonic probe, an ultrasonic probe of a type inserted into a body cavity, Furthermore, there are many types of ultrasonic probes, such as types of these various ultrasonic probes, depending on the difference in the frequency of the ultrasonic wave used. A connector (not shown) is used to attach the ultrasonic probe to the main body 10, but four connectors for connecting the ultrasonic probe are attached to the main body 10 as described above. In addition, up to four of the various types of ultrasonic probes can be simultaneously mounted. When the ultrasonic probe is mounted on the main body 10, information indicating which type of ultrasonic probe is mounted can be recognized by the main body 10. The information is stored in the control line 207 and the control interface 204. , And CPU bus 901
Is transmitted to the CPU unit 101 via. On the other hand, when using this ultrasonic diagnostic apparatus, an instruction is input from the operation panel 701 to which connector of the four connectors on the main body unit 10 to use this time. The instruction is transmitted to the beam scan control unit 102 via the CPU bus 901, and data corresponding to the ultrasonic probe to be used is transmitted from the beam scan control unit 102 to the CPU bus 901, the control interface unit 204, the control line The transmission / reception unit 201 is transmitted to the transmission / reception unit 201 via the transmission unit 207, and transmits a high-voltage pulse to the ultrasonic probe 20 designated as described above to transmit ultrasonic waves as described below. Receive the signal received by the ultrasound probe.
Here, it is assumed that only one ultrasonic probe 20 shown in FIG. 9 has been selected for transmitting and receiving ultrasonic waves.

The ultrasonic probe 20 shown in FIG. 9 is a so-called linear scanning type ultrasonic probe.
A plurality of ultrasonic transducers 21 are arranged, and when transmitting and receiving ultrasonic waves, the ultrasonic transducer 21 is applied to the body surface of the subject 1 (particularly a human body). In that state, the transmitting and receiving unit 2
Each high-voltage pulse for transmitting ultrasonic waves is applied from 01 to each of the plurality of ultrasonic transducers 21. The relative time difference between the high-voltage pulses applied to each of the plurality of ultrasonic transducers 21 is adjusted by the control of the control interface unit 204, and the relative time difference is adjusted according to how the relative time differences are adjusted. Then, a focus is formed from the plurality of ultrasonic transducers 21 at a predetermined depth position inside the subject along any one of the plurality of scanning lines 2 extending inside the subject 1. The transmitted ultrasonic pulse beam is transmitted.

The attributes of the transmitted ultrasonic pulse beam, that is, the direction of the ultrasonic pulse beam, the depth position of the focal point, the center frequency, etc., are determined by the beam scan controller 10.
2 is determined by the control data transmitted to the control interface unit 204 via the CPU bus 901. The ultrasonic pulse beam is reflected at each point on one scanning line while traveling inside the subject 1 and returns to the ultrasonic probe 20, and the reflected ultrasonic waves are transmitted to a plurality of ultrasonic transducers 21.
Received at. A plurality of reception signals obtained by this reception are input to the transmission / reception unit 201 and amplified by a plurality of preamplifiers (not shown) provided in the transmission / reception unit 201, respectively, and then input to the beam former unit 203. The beamformer unit 203 is provided with an analog delay line (described later) having a large number of intermediate taps. Under the control of the reception delay control unit 202, a plurality of reception signals transmitted from the transmission / reception unit 201 are transmitted. Which intermediate tap of the analog delay line is input from is switched, whereby
The plurality of received signals are relatively delayed and current added to each other. Here, by controlling the relative delay patterns for the plurality of received signals, reflected ultrasonic waves in a direction along a predetermined scanning line extending inside the subject 1 are emphasized, and a predetermined A so-called received ultrasonic beam is formed which is focused on the depth position. Here, since the ultrasonic waves travel inside the subject 1 slowly compared with the speed of the signal processing, the ultrasonic waves reach a deeper position in the subject while receiving the reflected ultrasonic waves along one scanning line. It is also possible to realize a so-called dynamic focus by sequentially moving the focal point. In this case, even during one reception corresponding to one transmission of the ultrasonic pulse beam,
On the way, the reception delay control unit 202
Thereby, each tap of the analog delay line to which each received signal obtained by each ultrasonic transducer is input is switched.

The attributes of the received ultrasonic beam, that is, the direction and focal position of the received ultrasonic beam, are also transmitted from the beam scan control unit 102 to the control interface unit 204 via the CPU bus 901, and further transmitted to the control line 207. Delay control unit 2 via
The reception delay control unit 202 controls the beamformer unit 203 based on the control data transmitted as described above.

In the above description, it has been described that a high-voltage pulse is applied to the ultrasonic vibrator 21 and an ultrasonic pulse beam is transmitted. In this case, as described above, the ultrasonic wave is compared with the signal processing speed. In order to proceed slowly inside the subject, the time was obtained from the time when the high voltage pulse was applied to the ultrasonic vibrator 21 until the time when the ultrasonic vibrator 21 received the reflected ultrasonic wave. It is possible to know at which depth position in the subject the signal is a signal corresponding to the reflected ultrasonic wave. That is, since the transmitted ultrasonic waves are pulsed, the ultrasonic waves have resolution in the depth direction of the subject. Normally, a high-voltage pulse is applied to the ultrasonic vibrator 21 as described above. In a special case, the ultrasonic vibrator 21 is allowed to have no resolution in the depth direction in the subject. In some cases, an ultrasonic beam as a continuous wave may be transmitted into the subject by applying a high-voltage pulse train signal that is continuously repeated to 21.

However, also in the following, the Doppler processing unit 4
In the description of the pulse / continuous wave Doppler analysis unit 401 constituting 00, a description will be given assuming that a pulse-like ultrasonic beam is transmitted, except when a continuous wave is referred to. Transceiver 20
1 and the beam former 203 repeat transmission and reception of the ultrasonic pulse beam sequentially along each of the plurality of scanning lines 2 inside the subject 1 as described above,
The reception signals representing the reception ultrasonic beams generated along the respective scanning lines are sequentially input to the arithmetic unit 205.
The arithmetic unit 205 performs logarithmic compression and detection of the input received signal, and further determines to which depth area inside the subject 1 the image is displayed by operating the operation panel 701. A filtering process or the like according to the designation (that is, designation of whether to display an image only in a shallow region inside the subject or how deep the region needs to be displayed) is performed. It is converted into a digital reception signal by the D converter, and this digital reception signal (the first reception signal in the present invention)
(An example of a second received signal according to the present invention) which represents a received ultrasonic beam having a small beam diameter based on the above-described calculation process based on the example of the received signal described above.
Is generated, and the generated reception signal is output from the arithmetic unit 205. The details of the calculation unit 205 will be described later. The received signal output from the arithmetic unit 205 is transmitted via the echo bus 902 to the black and white scan converter 30 constituting the digital scan converter unit 300.
1 is input. This black and white scan converter 301
Then, an interpolation operation for generating data corresponding to each pixel for display is performed, the input received signal is converted into a video signal for display, and the video signal for display is transmitted to the video bus 903. The data is input to the display control unit 500 via the control unit. The display control unit 500 displays a B-mode image based on the ultrasonic reflection intensity distribution in the tomographic plane of the subject defined by the plurality of scanning lines 2 on the observation television monitor 707. At this time, the patient name, imaging date, imaging conditions, and the like input from the operation panel 701 are also displayed as superimposed on the B-mode image as necessary. As the B-mode image, a moving image representing a state in which the inside of the subject 1 is moving can be displayed, or a still image at a certain point in time can be displayed. Based on the synchronization signal, it is possible to display an image of a phase of the heart motion synchronized with the heart motion of the human body.

An ECG electrode unit 70 for obtaining an electrocardiographic waveform of the subject (human body) 1 is
9, a heart sound microphone 710 for picking up a heart sound, and a pulse wave transducer 711 for capturing a pulse of a human body are connected. In the biological signal amplifier section 600, a synchronization signal is generated based on one or more of these sensors. Is generated and sent to the display control unit 500.

The display control unit 500 is connected to a printer 705 and a VTR (video tape recorder) 706 in addition to the television monitor 707 for observation. The display control unit 500 performs observation in response to an instruction from an operator. The image displayed on the television monitor 707 is output to the printer 705 or the VTR 706. Again, the signal processing unit 200
Start with the description.

When it is desired to know the time change of the ultrasonic reflection information on a single scan line extending into the subject, the ultrasonic change is performed along the scan line of interest in accordance with the instruction from the operator. Sound waves are repeatedly transmitted and received, and data representing a received ultrasonic beam of the subject along one scanning line is input to the scroll scan converter 303 via the echo bus 902. The scroll scan converter 303 includes an image (M-mode image) in which the ultrasonic reflection intensity distribution in the depth direction of the subject along one scanning line in the vertical direction and the horizontal axis is a time axis and scrolls in the time axis direction. ) Is generated, and a video bus 90 is generated.
The image is input to the display control unit 500 via the monitor 3 and an image based on the video signal is displayed on, for example, a television monitor 707 for observation. Note that the display control unit 500 includes a video signal representing a B-mode image transmitted from the monochrome scan converter 301 and the scroll scan converter 30.
3 and a function of superimposing a color mode image, which will be described later, on the B mode image. In response to the instruction from, a plurality of images are displayed side by side, or a plurality of images are displayed in a superimposed manner.

Returning to the description of the signal processing unit 200 again. The Doppler signal processing unit 206 included in the signal processing unit 200 is a component for obtaining a blood flow distribution inside the subject 1 and a blood flow velocity on a certain point or a certain scanning line. In the processing unit 206, a so-called orthogonal detection is performed on the reception signal representing the reception ultrasonic beam generated by the beam former unit 203, and further converted into digital data by A / D conversion. The data after the quadrature detection output from the Doppler signal processing unit 206 is input to the Doppler processing unit 400. The Doppler processing unit 400 includes a pulse / continuous wave Doppler analyzing unit 401 and a color Doppler analyzing unit 402. Here, data output from the Doppler signal processing unit 206 is input to the color Doppler analyzing unit 402. Shall be performed. The color Doppler analysis unit 402 performs an autocorrelation operation based on data when, for example, eight times of ultrasonic transmission / reception are performed along each scanning line, and a region of interest (ROI) on a B-mode image specified by an operator. Data representing the blood flow distribution in the interior is required. Data representing the blood flow distribution in the ROI is input to the color scan converter 302 via the echo bus 902. In the color scan converter 302, the ROI
The data representing the blood flow distribution in the inside is converted into a video signal suitable for display, and the video signal is input to the display control unit 500 via the video bus 903. Display control unit 5
In the ROI on the B-mode image sent from the black-and-white scan converter 301, the blood flow in the direction approaching the ultrasonic probe 20 is red, the blood flow in the direction away from the blue is blue, and the blood flow velocity is based on the brightness. Are superimposed and displayed on the television monitor 707 for observation.
Thereby, it is possible to grasp the outline of the blood flow distribution in the ROI.

Here, when the operator inputs a request for observing the blood flow on one point or one scanning line in the ROI in detail, the transmission / reception unit 20
1 repeats transmission / reception of ultrasonic waves many times in one scanning line passing through the point of interest or in the direction along the one scanning line of interest, and performs Doppler based on a signal obtained thereby. The data generated by the signal processing unit 206 is input to the pulse / continuous wave Doppler analysis unit 401 included in the Doppler processing unit 400. When the user is interested in a certain point of blood flow in the subject, a pulsed ultrasonic beam is transmitted into the subject, and the blood flow information on one scan line is allowed to be averaged. To obtain blood flow information with good S / N, an ultrasonic beam as a continuous wave is transmitted into the subject.

In the pulse / continuous wave Doppler analysis unit 401,
F based on data obtained by performing ultrasonic transmission / reception many times for a certain point or a certain scanning line
FT (Fast Fourier Transformer)
m) By the calculation, the blood flow information of the one point or the average blood flow information on the one scanning line is obtained. The data representing the blood flow information obtained by the pulse / continuous wave Doppler analysis unit 401 is input to the scroll scan converter 303 via the echo bus 902. A horizontal axis is a time axis, and a video signal representing an image scrolling in the time axis direction is generated. The video signal is input to the display control unit 500 via the video bus 903, and displayed on the observation television monitor 707 along with the B-mode image sent from, for example, the black-and-white scan converter 301.

FIG. 10 is a conceptual diagram showing a delay pattern of a high voltage pulse applied to a plurality of ultrasonic transducers.
Of the plurality of ultrasonic transducers 21 arranged, the ultrasonic transducer located at the center (O) of the array is temporally different from the ultrasonic transducers located at both ends (A) and (B) of the array. , A high-voltage pulse 212 is applied. By applying a high-voltage pulse having a delay pattern to the plurality of ultrasonic transducers 21 in this manner, the transmission ultrasonic wave extending in a predetermined direction in the subject and having a focal point formed at a certain depth position A pulse beam is formed.

FIG. 11 is a principle explanatory diagram showing a method of forming a received ultrasonic beam in the beam former section.
Here, for the sake of simplicity, delay lines 1001a,..., 1001m,.
Selection switches 1002a,..., 1002m for switching the input route of the received signal to the delay line according to the control signal.
, 1002n are provided corresponding to the respective ultrasonic transducers 21. Each selection switch 1002
, 1002m, one received signal obtained by one ultrasonic transducer 21 is input to each of the selection switches 1002a,..., 1002m,.
In 1002n, the input received signal is input to the delay line from the tap corresponding to the control signal among the plurality of taps of the delay line. Each delay line is 2001a,.
.., 2001n delay the input received signal by a delay time corresponding to the tap at which the received signal is input and input the delayed signal to the adder 1003. The adder 1003 adds the received signals simultaneously input to the adder 1003, and outputs a received signal representing a received ultrasonic beam.

In FIG. 11, the number of delay lines 1001a, 1001a,
, 1001m, ..., 1001n and selection switch 100
, 1002m,..., 1002n, and each delay line 1001a,.
.., 1001n, the configuration including the adder 103 for adding the received signals to each other has been described. However, in practice, a plurality of ultrasonic transducers are used to provide a single delay line having a large number of taps. The received signals are input while the input taps are respectively controlled, and the received signals are delayed by a time corresponding to the input taps, respectively, and are mutually current-driven in the delay line. From the one delay line, the received signals that have been delayed according to the controlled delay pattern and added together are:
Output directly.

FIG. 12 is an explanatory diagram showing the relationship among the delay pattern, the direction of the scanning line, and the focal position. It is assumed that a plurality of ultrasonic transducers are arranged between AB and AB.
The middle point between B is O. At this time, as shown in FIG. 12A, B is applied to the high voltage pulse applied to each ultrasonic transducer.
When a longer delay time is given to the ultrasonic transducer located on the side and applied to each ultrasonic transducer, a transmission ultrasonic beam is formed along a scanning line extending in a direction inclined from the midpoint O to the B side, As shown in FIG. 12 (B), when a symmetrical delay pattern is given, a transmission ultrasonic beam is formed along a scanning line extending from the midpoint O perpendicular to the arrangement direction of the ultrasonic transducers. As shown in), when a high voltage pulse having a longer delay time is applied to the ultrasonic transducer located on the A side, a transmitted ultrasonic beam inclined to the A side is obtained.
Further, even in the case of transmitting ultrasonic beams along the same scanning line, the focal position can be determined according to the delay pattern of the high-voltage pulse. Specifically, FIGS. 12 (A) to 12 (C)
As shown by a broken line in FIG. 2, consider drawing an arc tangent to a line segment connecting AB with the focus at the center. When the ultrasonic pulses transmitted from each ultrasonic transducer reach the arc at the same time, the ultrasonic pulses advance to be focused.
Therefore, for example, when a focal point is formed as shown in FIG. 12B, high voltage pulses are simultaneously applied to the ultrasonic transducers located at the points A and B, and the points A and B are applied by the application of the high voltage pulses. At the timing when the ultrasonic pulse emitted from the ultrasonic transducer located at the point reaches the arc, a high voltage pulse is applied to the ultrasonic transducer located at the point O and the ultrasonic vibration located at the point O An ultrasonic pulse is transmitted from the child. In this way, a transmission ultrasonic pulse beam having the narrowest beam diameter along the scanning line shown in FIG. 12B and at the focal position shown in FIG. 12B is formed.

Here, the plurality of ultrasonic transducers used for transmitting the ultrasonic waves arranged between A and B are, for example, a plurality of ultrasonic vibrators arranged on the ultrasonic probe 20 (see FIG. 9). A transmitting aperture, which is a part of the transducer 21 and includes a plurality of ultrasonic transducers used for forming a transmitting ultrasonic pulse beam,
By moving the ultrasonic transducers 21 arranged in the ultrasonic probe 20 in the arrangement direction, the scanning lines can be moved in parallel in the arrangement direction of the ultrasonic transducers 21.

As described above, starting from an arbitrary point on the ultrasonic transducers 21 arranged on the ultrasonic probe 20, the scanning line extends in an arbitrary direction in the subject and extends along an arbitrary point on the scanning line. A transmitted ultrasonic beam having a focal point can be obtained. The formation of the receiving ultrasonic beam is the same as that of the transmitting ultrasonic beam.

That is, as shown in FIG. 12 (A), each reception signal obtained by receiving the ultrasonic wave reflected in the subject and returned to each ultrasonic transducer by each ultrasonic transducer is shown in FIG. When a long delay time is given to the reception signals obtained by the ultrasonic transducers on the B side and added to each other, a reception ultrasonic beam is formed along the scanning line inclined from the middle point O to the B side. Then, as shown in FIG. 12 (B), when a symmetrical delay time is given and added to each other, the reception ultrasonic wave along the scanning line extending from the midpoint O as a starting point and perpendicular to the arrangement direction of the ultrasonic transducers A beam is formed, and as shown in FIG. 12 (C), a long delay time is given to the received signal obtained by the ultrasonic transducer on the A side, and the signals are added to each other. A received ultrasonic beam is obtained along the inclined scanning line. Further, even for the received ultrasonic beams along the same scanning line, the focal position can be determined according to the delay pattern. Specifically, each point A,
The ultrasonic waves directed to O and B will simultaneously reach the intersection of the arc with each line segment connecting the focal point and each point A, O and B, and the ultrasonic waves reflected at the focal point will be reflected by each ultrasonic transducer. There will be a difference in the time of reception. Therefore, the ultrasonic wave reflected by the focal point is delayed by the reception signal obtained by the ultrasonic vibrator that arrives first until the ultrasonic wave reaches the ultrasonic vibrator that the ultrasonic wave reaches later, The addition results in the formation of a most narrowed received ultrasound beam that extends in a direction along the scan line passing through the focal point and is at that focal point.

Here, as in the case of transmission, a plurality of ultrasonic transducers arranged between A and B and used for receiving reflected ultrasonic waves are, for example, the ultrasonic probe 20 (see FIG. 9).
A part of the plurality of ultrasonic transducers 21 arranged in
By moving the receiving aperture composed of a plurality of ultrasonic transducers used for receiving reflected ultrasonic waves in the direction in which the ultrasonic transducers 21 arranged on the ultrasonic probe 20 are arranged, scanning lines can be formed.
It can be translated in the direction of the arranged ultrasonic transducers 21.

As described above, for both transmission and reception, the scanning point extends along the scanning line extending in an arbitrary direction in the subject from an arbitrary point on the ultrasonic transducer 21 arranged on the ultrasonic probe 20 as a starting point. An ultrasonic beam having a focus at an arbitrary point on the scanning line can be obtained. FIG.
10 is a block diagram illustrating an example of an arithmetic processing circuit for a digital reception signal after A / D conversion in the arithmetic unit 205 illustrated in FIG. Here, the data of each point in the subject that constitutes the received signal after the A / D conversion is referred to as scanning line data. The arithmetic processing circuit shown in FIG.
(First-in First-out memory), these FIFOs each employ the output value of the counter 2050 as both the write address and the read address, and scan line 1
It has the capacity to store the scan line data for this line. Original scanning line data after A / D conversion (scanning line data representing a received ultrasonic beam having the actual beam profile (first ultrasonic beam referred to in the first ultrasonic diagnostic apparatus of the present invention)) is Three FIFOs 2051, 205
The data is sequentially input to the FIFO 2051 out of 2,2053. When the scan line data is sequentially input to the FIFO 2051, the write address of the FIFO 2051 is given by the output value of the counter 2050 that is counted up in synchronization with the control clock given from the control interface unit 204 (see FIG. 9).

The output value of the counter 2050 is also used as a read address of the FIFO 2051 at the same time.
The data previously stored at the address indicated by the output value of the FIFO 2051 is now written to the same address of the FIFO 2052. Similarly, the FIF
The data previously stored in O2052 is
It is written to the same address in O2053. With this configuration, scan line data of three adjacent scan lines (here, three scan lines L0, L1, and L2; see FIG. 13) is prepared.

The counter 2050 is reset by a scanning line switching signal provided from the control interface unit 204 shown in FIG. 9, and by this reset, its output value, that is, the write address and the read address of the FIFO are changed to the first address of the FIFO. To return to. The scan line data of the three scan lines L0, L1, and L2 prepared in this way are simultaneously input to the second-order differential operation unit 2055 at the same depth. Two pieces of scan line data of two scan lines L0 and L2 among the scan line data are input to the displacement calculator 2054. Second derivative operation unit 205
5, the second-order differentiation of the scanning line data as shown in FIG. 6 (when the scanning line data of the same depth on the scanning lines L0, L1, and L2 is L0, L1, and L2, respectively, The derivative is L0 + L2-2L1), and the displacement calculator 2050 calculates the displacement d according to the above-described equation (7).

The displacement obtained by the displacement calculation unit 2054 is
Stored in the FIFO 2059 and further stored in the FIFO 2060
Is stored in The second-order differential value obtained by the second-order differential operation unit 2055 is stored in the FIFO 2061, further stored in the FIFO 2062, and further stored in the FIFO 2062.
3 is stored. The scanning line data (amplitude value) read from the FIFO 2052 is stored in the FIFO 2053 and the FIFO 2056, and is stored in the FIFO 2056.
The amplitude value (scanning line data) stored in O2056 is then stored in FIFO 2057 and further stored in 2058.

Of the data stored in the FIFOs 2056 to 2063 in this way, the scan line data (amplitude value) currently focused on stored in the FIFO 2057 is input to the subtraction unit 2067 and stored in the FIFO 2060. The displacement data of the scanning line being input is input to the high-resolution difference luminance calculating unit 2064, and the FIFO 2056, 2
The scan line data of the next scan line and the previous scan line from the scan line of interest currently stored in 058 are sent to the black hole center luminance calculation unit 2065 and the black hole end luminance calculation unit 2066. Input and FIFO20
61, 2062, and 2063, the second derivative of the scan line of interest (FIFO 2062), the second derivative of the next scan line (FIFO 2061), and the second derivative of the previous scan line (FIFO 2061). FIFO 2063) is input to the black hole determination unit 2068.

In the high-resolution difference luminance calculator 2064,
The second term of the aforementioned equation (13), that is, a (k ² -1)
d ² is calculated, and the calculation result is input to the subtraction unit 2067. The subtraction unit 2067 also receives the scanning line data input from the FIFO 2057, that is, ln (C) shown in the first term of the expression (13). The subtraction unit 2067 performs subtraction between these two inputs. L shown in equation (13)
New scan line data representing n (C _c ), that is, a received ultrasonic beam having a small beam diameter (a second received ultrasonic beam in the first ultrasonic diagnostic apparatus of the present invention) is generated. The output ln (C _c ) of the subtraction unit 2067 is input to the selector 2069.

Also, black hole center luminance calculation 206
5, this embodiment has been described with reference to FIG.
+ D) / 2 is performed. The calculation result is also input to the selector 2069. Further, in the present embodiment, the black hole edge luminance calculation unit 2066 performs the calculation of ac and bc described with reference to FIG. The calculation result of the black hole edge luminance calculation unit 2066 is also input to the selector 2069.

The black hole determination unit 2068 includes FI
The second order differential values stored in the FOs 2061 to 2063 are input, and a threshold value is also input from the control interface unit 204 shown in FIG. 9, and the presence of a black hole is determined by the determination method described with reference to FIG. You. The result of the determination by the black hole determination unit 2068 is input to the selector 2069 as a luminance selection signal. In the selector 2069, if the current is one of the both ends of the black hole, the calculation obtained by the black hole edge luminance calculation unit 2066 The result is selected. In the case of the center of the black hole, the calculation result obtained by the black hole center luminance calculation unit 2065 is selected. When the result is neither the center nor both ends of the black hole, the calculation result is obtained by the subtraction unit 2067. The calculation result is selected.

Note that the black hole determination unit 2068
The center of the black hole is determined, at which point
The selector 2069 has a buffer similar to a FIFO inside the selector 2069 so that data relating to the black hole edge existing on the scanning line immediately before the scanning line where the center portion exists does not go too far in time. Is provided.

The selector 2069 outputs the data selected as described above (this is referred to as new scanning line data). The new scan line data output from the selector 2069 is input to the black-and-white scan converter 301 via the echo bus 902 shown in FIG. 9 and is converted to a video signal for display and then displayed via the video bus 903. The B-mode image is input to the control unit 500 and displayed on the display screen of the observation television monitor 707, for example, based on the new scanning line data obtained as described above.

The B-mode image based on the new scanning line data is a high-resolution image as described above and a high-quality image in which black holes are not conspicuous. FIG. 14 shows A / A in the arithmetic unit 205 shown in FIG.
FIG. 11 is a block diagram illustrating another example of a processing circuit for processing a digital reception signal after D conversion.

The blocks constituting the arithmetic processing circuit shown in FIG. 14 are given the same names and numbers as the blocks constituting the arithmetic processing circuit shown in FIG. 3, and each block is shown in FIG. An operation equivalent to an operation in a direction crossing a plurality of scanning lines in a corresponding block of the arithmetic processing circuit is executed in a direction in which the scanning lines extend (a depth direction). It should be noted that the relative timing shift due to the execution of each operation in a plurality of blocks is assumed to have a register or the like in any of the blocks and to be adjusted in timing.

Original scan line data after A / D conversion (received ultrasonic beam having actual burst wave pulse width (first received ultrasonic beam referred to in the second ultrasonic diagnostic apparatus of the present invention)
Is sequentially output for each sampling point, the displacement calculation unit 2054, the second-order differentiation calculation unit 2055,
It is input to the black hole center luminance calculator 2065, the black hole edge luminance calculator 2066, and the subtractor 2067. Here, three times t shown in FIG.
The description will be made assuming that the operation is performed at the timing of executing the operation on the sampling point at time t1 among the three adjacent sampling points at 0, t1, and t2.

The displacement calculating unit 205 calculates the displacement r in the depth direction according to the equation (19).
55, the second derivative of the scanning line data as shown in FIG. 6 (when the scanning line data (sampling data) at each time t0, t1, t2 is represented by t0, t1, t2, respectively, The differentiation is t0 + t2-2t1).

The displacement r obtained by the displacement calculation unit 2054
Is input to the high-resolution difference luminance calculation unit 2064, and the second-order differential value obtained by the second-order differentiation calculation unit 2055 is input to the black hole determination unit 2068. In the high-resolution difference luminance calculation unit 2064, the second expression
The term, that is, b (k ² -1) r ² is calculated, and the calculation result is input to the subtraction unit 2067. The scanning line data itself, that is, ln (F), which is the first term of the equation (25), is also input to the subtraction unit 2067, and the subtraction unit 2067 performs a subtraction between these two inputs. A new scanning line representing ln (F _c ) shown in the equation, that is, a received ultrasonic beam composed of a burst wave having a short pulse width (a second received ultrasonic beam in the second ultrasonic diagnostic apparatus of the present invention). Data is generated. Output 1 of this subtraction unit 2067
n (F _c ) is input to the selector 2069.

Also, the black hole center luminance calculating section 20
At 65, in the present embodiment, the calculation of (b + d) / 2 described with reference to FIG. 8 is performed. The calculation result is also input to the selector 2069. Further, in the present embodiment, the black hole edge luminance calculation unit 2066 performs the calculation of ac and bc described with reference to FIG. The calculation result of the black hole edge luminance calculation unit 2066 is input to the selector 2069.

The second order differential value obtained by the second order differential operation unit 2055 is input to the black hole determination unit 2068, and the threshold value from the control interface unit 204 shown in FIG. 9 is also input to the black hole determination unit 2068. The presence of a black hole is determined by the described determination method. The result of the determination by the black hole determination unit 2068 is input to the selector 2069 as a luminance selection signal. In the selector 2069, in the case where the current is one of both ends of the black hole, the black hole edge luminance calculation unit 2066 obtains the result. The calculation result is selected, and in the case of the center of the black hole, the calculation result obtained in the black hole center luminance calculation unit 2065 is selected. When the calculation result is neither the center nor the both ends of the black hole, the calculation result is obtained in the subtraction unit 2067. Is selected.

The selector 2069 outputs the data (new scanning line data) selected as described above. The new scanning line data output from the selector 2069 is
As in the description of FIG. 13, the signal is input to the black-and-white scan converter 301 via the echo bus 902 shown in FIG. 9, converted into a video signal for display, and then input to the display control unit 500 via the video bus 903. For example, on the display screen of the observation television monitor 707, a B-mode image based on the new scanning line data obtained as described above is displayed. The B-mode image based on the new scanning line data is a high-resolution image in the depth direction and a high-quality image in which black holes are inconspicuous.

In the above, the arithmetic processing circuits for improving the resolution in each of the direction traversing a plurality of scanning lines and in the depth direction and making the black holes less noticeable have been described. The resolution may be increased both in the direction crossing the line and in the depth direction, or an operation may be performed to combine the two directions to make the black hole less noticeable.

[0109]

As described above, according to the present invention,
An ultrasonic diagnostic apparatus capable of obtaining an image with higher spatial resolution than before is realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a beam profile of a received ultrasonic beam.

FIG. 2 is a schematic diagram of a beam profile (burst wave profile) of an ultrasonic beam in a depth direction.

FIG. 3 is a schematic diagram in which an image including a plurality of scanning lines and a black hole is overlaid.

FIG. 4 is a graph showing scan line data along a transverse line AA ′ extending across the plurality of scan lines shown in FIG. 3;

FIG. 5 is a graph showing scanning line data when a received ultrasonic beam having an actual beam profile is used and scanning line data having a beam profile having a narrow beam diameter or a short pulse width.

FIG. 6 is a graph showing the second derivative of scanning line data.

FIG. 7 is an explanatory diagram of a method of correcting scan line data at both ends of a black hole.

FIG. 8 is an explanatory diagram of another example of a method of correcting scanning line data at both ends of a black hole.

FIG. 9 is a block diagram showing an embodiment of the ultrasonic diagnostic apparatus of the present invention.

FIG. 10 is a conceptual diagram showing a delay pattern of a high voltage pulse applied to a plurality of ultrasonic transducers.

FIG. 11 is a principle explanatory diagram showing a method of forming a reception ultrasonic beam in a beam former unit.

FIG. 12 is an explanatory diagram showing a relationship among a delay pattern, a direction of a scanning line, and a focal position.

13 is a block diagram illustrating an example of an arithmetic processing circuit for a digital reception signal after A / D conversion in the arithmetic unit illustrated in FIG. 9;

14 is a block diagram illustrating another example of the arithmetic processing circuit for the digital reception signal after A / D conversion in the arithmetic unit illustrated in FIG. 9;

FIG. 15 is a schematic diagram showing how an image of the target is obtained when a target (ultrasonic reflector) is present at a certain point in the subject using the ultrasonic diagnostic apparatus.

FIG. 16 is a schematic diagram showing a signal waveform of an ultrasonic wave reflected and returned by a target in a subject and a process of processing the signal.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 subject 2 scanning line 10 main body unit 20 ultrasonic probe 21 ultrasonic transducer 100 control unit 101 CPU unit 102 beam scan control unit 200 signal processing unit 201 transmission and reception unit 202 reception delay control unit 203 beam former unit 204 control interface unit 205 Operation unit 206 Doppler signal processing unit 207, 208, 209 Control line 300 Digital scan converter unit 301 Black / white scan converter 302 Color scan converter 303 Scroll scan converter 400 Doppler processing unit 401 Pulse / continuous wave Doppler analysis unit 402 Color Doppler analysis unit 500 display control unit 600 biological signal amplifier unit 701 operation panel 702 touch panel 703 EL display unit 704 floppy disk device 705 pre Motor 706 VTR 707 observation television monitor 708 speaker 709 ECG electrode unit 710 heart sound microphone 711 pulse wave transducer 800 power supply unit 901 CPU bus 902 Ekobasu 903 video bus

Claims (12)

[Claims] An ultrasonic wave transmitted into a subject, reflected from the subject and returned, receives a first ultrasonic wave along a predetermined scanning line extending into the subject. Transmitting / receiving means for sequentially repeating a process of generating a received signal for a plurality of different scanning lines; and a plurality of first receiving ultrasonic beams along a plurality of different scanning lines obtained by the transmitting / receiving means. Calculating means for executing a second received signal representing a second received ultrasonic beam along a predetermined scanning line based on the received signal for a plurality of different scanning lines; and And an image output means for outputting an image based on the obtained second received signal. 2. The method according to claim 1, wherein the calculating unit generates the second reception signal by executing an operation including an operation for obtaining a position of the ultrasonic reflection source in the subject. 2. The ultrasonic diagnostic apparatus according to claim 1. 3. The method according to claim 1, wherein the calculating means is configured to interpose a predetermined scanning line.
An operation for calculating the distance of the ultrasonic reflection source in the subject from the predetermined scanning line based on two first reception signals representing two first reception ultrasonic beams along the scanning lines 3. An ultrasonic diagnostic apparatus according to claim 2, wherein a second reception signal representing a second reception ultrasonic beam along said predetermined scanning line is generated by executing an operation including: . 4. The arithmetic unit according to claim 1, wherein the second reception signal representing a second reception ultrasonic beam having a beam diameter smaller than the beam diameter of the first reception ultrasonic beam represented by the first reception signal is provided. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus performs a calculation to be generated. 5. The method according to claim 1, wherein the calculating unit is configured to determine, based on a change in the first reception signal in a vicinity of the predetermined scanning line, on a predetermined transverse line that crosses a plurality of scanning lines including the predetermined scanning line. A new received signal for the intersection is replaced with the second received signal for the intersection of at least one of the predetermined scanning line and the scanning line adjacent to the predetermined scanning line and the predetermined transverse line. It is determined whether or not to adopt, and when a condition for employing a new reception signal is satisfied, a new reception signal is employed for the intersection instead of the second reception signal for the intersection. Claim 4
An ultrasonic diagnostic apparatus as described in the above. 6. The arithmetic unit determines a differential value of the first received signal in a direction along the predetermined transverse line at an intersection of the predetermined transverse line and the predetermined scan line, and calculates the differential value. Is compared with a predetermined threshold value.
Determining whether to adopt a new reception signal for the intersection of the predetermined crossing line and the at least one scanning line instead of the second reception signal for the intersection. Item 7. An ultrasonic diagnostic apparatus according to Item 5. 7. A first received ultrasonic beam along a predetermined scanning line extending in a subject is received by receiving an ultrasonic wave transmitted in a burst wave shape in the subject and reflected back in the subject. Transmission / reception means for generating a first reception signal; first transmission / reception means along a predetermined scanning line obtained by the transmission / reception means
Calculating means for executing a calculation for generating a second reception signal representing a second reception ultrasonic beam along the predetermined scanning line based on the first reception signal representing the reception ultrasonic beam of the above, And an image output means for outputting an image based on the second reception signal obtained in (1). 8. The second receiving signal is obtained by executing an operation including an operation for obtaining a depth position of an ultrasonic reflection source in the subject in a direction along the predetermined scanning line. The ultrasonic diagnostic apparatus according to claim 7, wherein the ultrasonic diagnostic apparatus is generated. 9. The method according to claim 1, wherein the calculating unit is configured to determine whether the ultrasonic reflection source in the subject is at a predetermined point on the predetermined scanning line based on first reception signals related to two points on the predetermined scanning line. By performing an operation including an operation for obtaining a distance from the predetermined point in a direction along the scanning line, a second reception signal representing a second reception ultrasonic beam along the predetermined scanning line is generated. 9. The ultrasonic diagnostic apparatus according to claim 8, wherein the ultrasonic diagnostic apparatus is an ultrasonic diagnostic apparatus. 10. The method according to claim 1, wherein the calculating unit is configured to represent a second received ultrasonic beam having a higher resolution than a first received ultrasonic beam represented by the first received signal in a direction along the scanning line. 8. The ultrasonic diagnostic apparatus according to claim 7, wherein the ultrasonic diagnostic apparatus performs an operation for generating the second reception signal. 11. The method according to claim 1, wherein the calculating unit is configured to perform a
Based on a change in the first received signal in the vicinity of a predetermined point, the second received signal is replaced with at least one of points near the predetermined point on the predetermined scanning line, including the predetermined point. It is determined whether or not to adopt a new received signal for the point, and when a condition for employing the new received signal is satisfied, a new received signal for the point is substituted for the second received signal for the point. The ultrasonic diagnostic apparatus according to claim 10, wherein: 12. The arithmetic means calculates a differential value of the first received signal in a direction along the predetermined scanning line at the predetermined point, and compares the differential value with a predetermined threshold value. By doing so, whether to adopt a new reception signal for the point in place of the second reception signal for at least one of points near the predetermined point on the predetermined scanning line, including the predetermined point, 12. The ultrasonic diagnostic apparatus according to claim 11, wherein the ultrasonic diagnostic apparatus is configured to determine whether or not the ultrasonic diagnosis is performed.