JPS6318501B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus using a manual contact scan method that achieves uniformity of images.

Manual contact scan type ultrasound diagnostic equipment emits pulsed ultrasound waves and captures the reflected waves by holding the transducer in your hand and scanning it while keeping it in close contact with the patient's body surface. An ultrasound image is obtained by capturing ultrasound echoes and displaying them on a cathode ray tube.

Here, the circuit configuration of the conventional device is shown as a block diagram in FIG. 1, and its outline will be explained.
In the figure, 1 is a rate pulse oscillation circuit that generates a rate pulse that serves as a reference signal for the device, 2 is a pulser that generates a transmission pulse in synchronization with the time of this rate pulse, and 3 is a signal that exceeds the signal from pulser 2. A transducer that converts the ultrasonic echoes that are emitted and reflected into sound waves and converts them into electrical signals; 4 is a preamplifier that amplifies the ultrasonic echoes captured by the transducer 3 and converted into electrical signals; 5; 6 is a detection circuit that detects the output of the preamplifier 4, 6 is a filter that waves the detected output, 7 is a video amplifier circuit that amplifies the ultrasonic echo signal that has passed through the filter 6 to a signal level sufficient as a video signal, and 8 is the rate mentioned above. A blanking circuit synchronizes with pulses and superimposes a blanking signal on the video signal, and reference numeral 9 denotes a bendable support arm 9 with the vibrator 3 attached to its tip.
a, the bending angle of this support arm 9a and the vibrator 3
A scanner 10 detects the swing angle, etc. of the transducer 3 using the detection signal from the scanner 9.
and a position detection circuit that performs position detection in the Y-axis direction;
11 is an X-axis sweep signal generation circuit that generates a sweep signal in the X-axis direction according to the signal from the position detection circuit 10, and 12 generates a sweep signal in the Y-axis direction according to the signal from the position detection circuit 10. The Y-axis direction sweep signal generation circuit 13 is swept along the XY axes by the signals from these X-axis and Y-axis direction sweep signal generation circuits 11 and 12, and is luminance-modulated by the output signal of the blanking circuit 8 to generate an ultrasonic echo. It is a monitor cathode ray tube that displays images.

The conventional device with such a configuration generates a high frequency signal in the pulser 2 for the time width of this pulse based on the rate pulse obtained by oscillating the rate pulse oscillation circuit 1, and contacts the subject's body surface with this. In addition to the vibrator 3, the ultrasonic waves are converted into ultrasonic waves and irradiated into the subject's body. A portion of the irradiated ultrasound waves is reflected by parts of different compositions within the body, and returns to the transducer 3 as ultrasound echoes. This ultrasonic echo is captured by a transducer 3, converted into an electrical signal, and then amplified by a preamplifier 4, passed through a detection circuit 5 and a filter 6 to obtain a video signal, which is then sent to a video amplification circuit 7 to generate a signal sufficient as a video signal. amplify the level. Then, this signal is applied to the blanking circuit 8 together with the rate pulse described above, and the blanking signal is superimposed and applied to the brightness modulation terminal of the monitor cathode ray tube 13. on the other hand,
In order to obtain an ultrasound image, it is necessary to control the position of the spot beam of the monitor cathode ray tube 13 according to the position of the transducer 3, so depending on the angle of the arm 9a of the scanner 9 that supports the transducer 3, etc. , the position in the Y-axis direction is detected, and these signals are converted into position signals by the position detection circuit 10, and the positions are detected in the X-axis direction,
In addition to the Y-axis direction sweep signal generation circuits 11 and 12, X-axis and Y-axis sweep signals are generated in accordance with the position signal. When this is applied to the X-axis and Y-axis sweep input terminals of the monitor cathode ray tube 13 and the spot beam is swept, an ultrasonic echo is displayed on the cathode ray tube 13.

In such a conventional device, the captured ultrasonic echoes are displayed on the cathode ray tube 13 in accordance with the position of the transducer 3, so in order to observe the cross-sectional image of the affected area of the subject, the transducer The transducer 3 must be moved along the cross section, but the movement of the transducer 3 is a manual operation, and the body surface is not a uniform curved surface, but has various unevenness depending on the part such as the chest, so the transducer 3 must be moved along the cross section. 3 does not necessarily move in a direction perpendicular to the beam center axis, but moves in various ways, for example, in a spiral as shown in FIG. In such a case, the area irradiated with the ultrasonic beam in duplicate becomes a striped pattern as shown in Figure 3, and if the device is a conventional one, the area is irradiated with the beam in the direction of beam irradiation or in the opposite direction to the direction of beam irradiation as shown in Figure 4. When the transducer 3 is moved, lines and the like appear due to the overlap of the ultrasonic beams, resulting in an image with non-uniform density.

The present invention was made in view of the above circumstances, and detects the direction of the transducer (the direction of the ultrasonic beam) and the direction of movement of the transducer, and detects the direction of the transducer so that the difference between the angles indicating the directions of the two is within a certain range. An object of the present invention is to provide an ultrasonic diagnostic apparatus that eliminates the bright line at that location to homogenize the image on the cathode ray tube and make it easier to see.

5 to 9 regarding one embodiment of the present invention.
This will be explained with reference to the figures.

Generally, on an uneven surface on the body surface, the oscillator 3 tilts along the uneven surface, and the oscillator 3 does not necessarily move in a direction perpendicular to the beam direction, but as shown in FIG. The direction of movement of the vibrator 3 no longer matches. By expressing this angular difference as α, calculating it, and adding it to one of the elements for control, a more uniform image can be obtained.

That is, when the moving direction of the transducer 3 and the transmission direction of the ultrasonic beam become less than a predetermined angle, (a) this is input as a reset signal to the rate pulse oscillation circuit 1, and pulse oscillation is stopped.

Or (b) during that period, the blanking circuit 8 generates a blanking signal to prevent the bright line from appearing.

Or (c) during that period, the gain of the amplifier circuit 7 (or the integrated amplifier 4 may also be used) is lowered to adjust the brightness.

Perform either of the following controls.

To do this, as shown in FIG. 5, by comparing the velocity vector υ _P of the oscillator 3 as it moves from the oscillator 3 at the A position to the B position, this velocity vector _υ Oscillator 3 in
When the velocity vector of this oscillator 3 becomes less than or equal to
It is assumed that the brightness line is not scanned in the horizontal direction (X direction), and the brightness line and brightness are control.

Detection of the presence or absence of scanning in the X direction is performed as follows.

Now, if the velocity vector of the vibrator 3 due to movement from point A to point B in Fig. 5 is υ _P , the X-axis direction component υ _XP and Y-axis direction component υ _YP of this velocity vector υ _P are υ _XP = υ _P cosα _{υ YP =} υ _P sinα V(θ,
As can be seen from the figure, α) is V(θ, α) = |υ _XP sin(2π−θ)−υ _YP
sin [(2π−θ)−π/2]｜=|υ _XP sin(2π−θ)−υ _YP cos(2π−
_{θ ) ｜ = ｜} υ The result will be as shown in Figure 6. Comparing this value of V (θ, α) with the value υ _S proportional to υ _P , we find that V (θ, α)≦υ _S (=Kυ _P ) where K is a constant and 0≦｜K｜≦1 ｜υ _P | | sin (θ−α) | ≦ | K | | υ _P | | sin (θ − α) | ≦π＋β……(2) The following relationship is obtained.

Here, (θ-α), that is, when the angle formed by the moving direction of the vibrator 3 and the horizontal axis satisfies the relationships of equations (1) and (2) above, the above (a), (b), and (c) are satisfied. control.

The same holds true when (π/2-α)=γ, and the angle between the moving direction of the vibrator 3 and the Y-axis is less than β.

That is, equation (1) shows when the oscillator is moving in the beam direction, and equation (2) shows when the oscillator is moving in the opposite direction to the beam direction.

Therefore, when the signal becomes less than υ _S , if you turn off the signal, the difference between the direction of motion of the oscillator and the direction of the beam becomes β.
When the difference between the moving direction of the vibrator and the opposite direction of the beam direction becomes less than β, the image disappears on the cathode ray tube surface.

In other words, as shown in FIG.
4 and a line 15 indicating the direction of movement of the vibrator when the angle γ is less than β, the image disappears on the cathode ray tube surface.

FIG. 8 is a block diagram of the operation described above.

In the figure, 20 detects the current position (x〓, y〓) of the vibrator 3 within its movement range as the support arm 9a of the scanner 9 supporting the vibrator 3 moves, and generates a position signal. The transducer position detection circuit 21 determines the radiation direction ( The ultrasonic beam radiation direction detection circuit 22 detects sinθ, cosθ), and the ultrasonic beam radiation direction detection circuit 22 sets a predetermined depth l (see Fig. 9) (a predetermined distance with respect to the radiation direction of the ultrasonic beam emitted from the transducer 3). , a distance setting circuit 23 that outputs a distance signal according to the set value, and 23 determines the position P at the preset distance l based on these three types of signals (position signal, radial direction signal, distance signal). (x _P , y _P ) (see Fig. 9, hereinafter referred to as the P position); 24 is an ultrasonic wave at the P position based on the change in the output signal of the P position detection circuit 23, which is sequentially outputted; A differentiating circuit 25 calculates the moving speed of the beam center axis in the _x direction and y _axis direction _{( υ} ²
A vector sum calculation circuit that calculates +υ _YP ² and generates a threshold voltage υ _S corresponding to that value, 26
inputs the output of the _{differentiation} circuit 24 (velocity signal _υ A multiplication circuit 27 to be obtained is the output of the differentiating circuit 24 (velocity signal υ _YP ) and the ultrasonic beam radiation direction detection circuit 2.
1 (angle signal cos θ) is input and multiplies both inputs to obtain υ _YP × cos θ (Y component vector). 28 is the multiplication circuit 26, 27.
A subtraction circuit takes the output of the subtraction circuit 28 as input and subtracts the latter from the former to obtain |υ _XP sinθ−υ _YP cosθ|=υ _P × |sin(θ−α)| This is a comparison circuit that compares the output of the sum calculation circuit 25 and detects a range of υ _P ×|sin(θ−α)|≦υ _S.

Next, the operation of this apparatus having the above configuration will be explained.

A transducer position signal (x〓, y〓) from the transducer position detection circuit 20, a signal indicating the beam radiation direction from the ultrasonic beam radiation direction detection circuit 21 (cos θ, sin θ),
A signal indicating the distance l is obtained from the distance setter 22, and based on these three pieces of information, the adder circuit 23 detects the position signal (x _P , y _P ) of the point P. Next, the differentiating circuit 24 calculates the velocity (υ _XP , υ _YP ) of point P in the x and y directions.
seek. The obtained result is sent to the vector sum circuit 25.
, and find the signal υ _S (∝υ _P ) that provides a threshold proportional to υ _P (=√ _XP ² + _YP ² ). On the other hand, the angle signals (cos θ, sin θ) from the ultrasonic beam radiation direction detection circuit 21 and the velocity _signals ( _υ
7, and here they are multiplied to give υ _XP
Find the values of ×sinθ and υ _YP ×cosθ. Next, the results of the multiplication circuits 26 and 27 are given to the subtraction circuit 28, and by this subtraction circuit 28 |υ _XP sinθ−
The value of υ _YP cosθ | = υ _P × | sin (θ − α) | is found. Furthermore, in the comparison circuit 29, υ _P × | sin (θ−α)
| and υ _S (∝υ _P ). and υ _P ×｜sin
In the range where (θ−α)|≦υ _S , the image on the cathode ray tube surface is erased. The first method for erasing the image on the cathode ray tube surface is to apply the output of the comparator circuit to the reset terminal of rate pulse oscillator 1 to stop the oscillation of the rate pulse, thereby stopping the transmission and reception of ultrasonic pulses, and As a second example, the output of the comparison circuit is added to the blanking circuit 8 to reduce the brightness and no image appears.As a third example, the output of the comparison circuit is A method such as changing the amplification degree of the amplifier 4 depending on the output may be used. Although υ _P = √ _XP ² + _YP ² was calculated using the vector _sum circuit 25, considering the difficulty of the circuit, υ _P = |
A sufficient effect can be obtained even if it is given as |υ _YP |.

Furthermore, by setting the threshold level υ _S , we can further develop the process of erasing the image and control the rate pulse or the amplification, brightness, etc. in proportion to the value of V (α, θ). Accordingly, an image with uniform density can be obtained regardless of the scanning direction of the transducer with respect to the beam direction.

As detailed above, this invention detects the direction of the ultrasonic transducer and the direction of movement, and when the difference between the angles indicating the two directions falls within a certain range, the bright line at that point is eliminated. To provide an ultrasonic diagnostic device capable of obtaining high-quality images even when an ultrasonic transducer is moved irregularly, especially in a manual contact scan method, since the image on a cathode ray tube is made homogeneous. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of a conventional ultrasonic diagnostic device, Fig. 2 is a diagram showing an example of manual multi-scan operation, and Fig. 3 is an image obtained by the scan operation shown in Fig. 2. Figure, 4th
The figure is a diagram explaining another example of manual multi-scan operation, FIG. 5 is a diagram explaining the operating principle of the embodiment of the present invention, and FIG. 6 is a diagram showing changes in V (α, θ) in the above embodiment. 7 is a diagram explaining the scan operation in which an image is erased in the above embodiment, FIG. 8 is a block diagram showing an example of the other embodiment described above, and FIG. 9 is a diagram showing the rotation angle and depth of the transducer. FIG. 3 is a diagram for explaining detection points. 20... Vibrator position detection circuit, 21... Ultrasonic beam radiation direction detection circuit, 22... Distance setting circuit, 23... Addition circuit, 24... Differentiation circuit, 25
. . . vector sum calculation circuit, 26, 27 . . . multiplication circuit, 28 . . . subtraction circuit, 29 . . . comparison circuit.

Claims (1)

[Claims] 1 A transducer that transmits ultrasonic waves based on an output signal from an oscillator scans the subject, detects the obtained ultrasonic echo from within the subject, and transmits the echo information via an amplifier to the transducer. An ultrasonic wave that controls and displays an X- and Y-axis sweep signal to a display device according to the position of the ultrasonic wave, and modulates the brightness according to an output signal from a blanking circuit to the display device to display an ultrasonic echo image as a bright line. An ultrasonic diagnostic apparatus, characterized in that the moving direction of the transducer is detected, and the bright line is controlled by this detection signal.