JPS6148950B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic imaging device that images an object by applying an ultrasonic pulse method.

Contrast imaging using the ultrasonic pulse method scans an ultrasonic beam on a flat surface, as is used in sonar, fish finders, and medical ultrasonic tomography devices.
A common method is to display and record the position of a reflector on a cross section of an object, but this method has the disadvantage that the image is flat and cannot express depth.

In addition, as a method for observing an object three-dimensionally using this method, for example, Japanese Patent Publication No. 1983-20267 discloses a method of viewing through a film of multiple parallel cross-sectional images, but this method does not provide intermittent depth information. If the number of films is increased in order to improve this point, it will be difficult to see through the entire film due to the limited light transmittance of the film, and the number of film shots will be large, resulting in poor operability, which is impractical. An electrical version of this method has also been proposed, but this method is easier to understand in practical terms because the direction in which the object is observed is perpendicular to the plane scanned by the ultrasound beam. It is not possible to obtain an image observed from the direction in which the acoustic beam is irradiated.

Therefore, the present invention makes it possible to obtain a scaled-down image of a distant view of an object observed from the direction in which the ultrasound is irradiated, and also enables stereoscopic vision of the object by observation from the direction in which the ultrasound is irradiated. 2 with parallax
The present invention proposes an ultrasonic imaging device that can obtain more than one image.

That is, the present invention attempts to obtain an image in which a reduction of a distant view is reproduced by synthesizing images based on the principle of reduction reproduction of a distant view.

The principle of reduction reproduction of a distant view is as shown in Fig. 1, where a vector A is located at a distance a from the observer's eye position P, and a vector A is located at a distance b (further distance c from the distance a).
If we observe a vector B which is located at a distance from the object A and has the same length as the object A, then this vector B will appear to be shorter than the object A, and at the position of the vector A, it will appear to have the length of the vector B'. The length of this vector B' for vector B is B'=a/b・B=a/a+c・B.

Also, as shown in Figure 2, when looking at the vector C located horizontally from the upper end of the vector A at a distance a from the eye position P, its length appears to be the length of the vector C'. becomes this vector
The length of C' is C'=C/a+C・A.

This also applies to the three-dimensional relationship shown in FIG. 3, and the same result can be obtained if the vector D in the depth direction is vectorially decomposed into the X-axis and Y-axis. That is, a cube S is placed at a distance a from the eye position P, and the base point of the vector D on one side in the depth direction is Letting the distance in the axial direction be x and the distance in the Y-axis direction be y, vector D _X decomposed from the base point of vector D to the X axis and vector D _Y decomposed to the _Y axis are D _Y =D/a+D・y.

Therefore, if this principle is reproduced by XY scanning using probe 1 as shown in Figure 4A, probe 1 will be
When scanning of the first sheet S ₁ is completed, Y
In other words, the second sheet _S2 is scanned in the X direction, that is, the second sheet _S2 is scanned from the beginning in the X direction. This is repeated in sequence at S ₃ ... S ₆ , and probe 1
The ultrasonic pulse is sent towards the target. If a reflector exists on this scanning path, a portion of the reflected light is reflected and received by the probe 1 again. The distance between the probe and the reflector at this time is proportional to the time from when the wave is transmitted until when the wave is received.

In this case, the position of the probe 1 is made to correspond to the surface of the cathode ray tube, and the bright spot of the cathode ray tube is moved according to the scanning of the probe 1, so that when a reflected wave is obtained, the bright spot is brightened. As a result, an image of the reflector is obtained on the cathode ray tube, but this image is contrasted to the same size regardless of the distance between the reflector and the probe 1, and there is no reduction in the distant view.

Therefore, as shown in Fig. 4B, the bright spot is swept toward the viewpoint position P' on the cathode ray tube C every time an ultrasonic pulse is transmitted, and the bright spot becomes brighter when a reflected wave is obtained. The image obtained on the cathode ray tube C is a reduced view of the distant view. This viewpoint position
The sweep toward point P' is performed using the coordinates X _P ', Y _P ' of viewpoint P' on the cathode ray tube, the position of probe 1 at X', Y', the constant corresponding to the speed of sound D, and the ultrasonic pulse. If the time from transmission to reception is t, the coordinates of the bright spot are X′t=X′−D・t/a+D・t(X′−X _P ′), Y′t=Y′ −D・t/a+D・t(Y′−Y _P ′).

Therefore, based on this principle, a system diagram shown in Fig. 5 shows a first embodiment in which an image that reproduces the reduction of a distant view is obtained in one screen, and multiple images with different viewpoint positions are synthesized in a time-sharing manner. I will explain about it.

First, the probe 1 scans the target object linearly in the X-axis direction using the XY-axis scanning mechanism 11, while
Scanned at low speed in the axial direction. This probe 1 has a transmitter circuit 1 driven by a signal from a clock circuit 12.
3, the target object is irradiated with ultrasonic pulses.
A portion of this ultrasonic pulse is reflected from the target object and is received by the wave receiving circuit 14 via the probe 1, and the output signal of this wave receiving circuit 14 is controlled by the signal from the clock circuit 12. When a signal applied to the Z axis of the cathode ray tube display device 16 through the unblanking circuit 15 and reflected from the target object is obtained, the bright spot is made to shine brightly.

On the other hand, the sawtooth wave generating circuit 17 is connected to the clock circuit 1.
A sawtooth wave voltage that starts rising each time probe 1 sends an ultrasonic pulse due to the signal from 2.
A voltage corresponding to Vt, that is, the time from transmission to reception, is generated, and this sawtooth wave voltage Vt is supplied to first and second arithmetic circuits 18 and 19.

The output signal of the clock circuit 12 is also supplied to a 1/2 frequency divider circuit 21, and the output signal of this 1/2 frequency divider circuit 21 is supplied to an inter-viewpoint distance adjustment circuit 22 and a left and right image distance adjustment circuit 23. , inter-view distance adjustment circuit 2
The output voltage of No. 2, that _is , the visual point This first
The arithmetic circuit 18 includes sawtooth wave voltage Vt as well as XY
X position signal voltage V of the probe 1 from the axis scanning mechanism 11
_X is supplied, and the viewing distance signal voltage Va is also supplied, so the output voltage V _X ′ is V _{X ′} =V _X −Vt/ _Va + _Vt ( _{V Va} + _Vt (V be done.

On the other hand, the second arithmetic circuit 19 has a sawtooth wave voltage.
Along with Vt, the Y axis of the probe 1 from the XY axis scanning mechanism 11 is
The position signal voltage V _Y is supplied, and the Y position voltage V _PY of the viewpoint with respect to the object and the viewing distance voltage Va are also supplied, and calculations are performed using these input voltages to obtain the output voltage V _Y ′ V _Y ′=V _Y - Vt/Va+Vt (V _Y - V _PY ) is output.

The output voltage V _Y ' from this second arithmetic circuit 19 is supplied to the Y axis of the cathode ray tube display device 16.

Therefore, the screen position on the cathode ray tube of the cathode ray tube display device 16 is distributed to the left and right, and the left and right images are synthesized on the same cathode ray tube screen in a time-sharing manner. The left and right images thus contrasted on the cathode ray tube display device 16 are transferred to the cathode ray tube imaging device 20.
By combining on the film 3, a stereo pair can be obtained.

Furthermore, in this embodiment, left and right images are combined each time an ultrasonic pulse is transmitted, but this division of left and right images may be performed at a higher speed in a shorter time than the transmitted pulse, for example, If the transmission pulse is about 3 μs, which is used for in-vivo contrast imaging, it is possible to divide the image between left and right by repeating the pulse at about 2 MHz. In this way, the number of picture elements per screen is halved compared to the case of a fixed viewpoint, but the same scanning completion time can be obtained. Furthermore, if the number of picture elements is the same as in the case of a fixed viewpoint, the scanning completion time will be doubled.

Further, FIG. 6 shows a second embodiment of the present invention,
The first embodiment described above is designed to obtain a set of two images with parallax that allows stereoscopic vision when observed from a direction perpendicular to the scanning plane, but this second embodiment is similar to the first embodiment. Using the same method as in the example, three sets of two images with parallax that allow stereoscopic vision observed from three directions perpendicular to the scanning plane are used to synthesize three sets, or six images, on one screen in a time-sharing manner. This is what I am trying to do.

The operation of this example will be explained below with reference to FIG.
That is, the probe 1 is scanned at a low speed in the Y-axis direction while scanning the target object in the X-axis direction by an XY-axis scanning mechanism 11, and a wave transmitting circuit 13 is driven by a signal from a clock circuit 12. The receiving circuit 14 transmits and receives ultrasonic pulses, and the 1/2 frequency dividing circuit 21 divides the image of the target object into left and right images at 1/2 period of the transmitted wave. Although it is similar to the first embodiment, in this example, a 1/3 frequency divider circuit 25 is connected to the 1/2 frequency divider circuit 21 and the output signal of this 1/3 period is supplied to the switching control circuit 26. Then, the three-point switching circuit 27 is operated to switch the X position signal voltage V _X , the Y position signal voltage V _Y of the XY-axis scanning mechanism 11, and the sawtooth wave signal voltage Vt of the sawtooth wave generation circuit 17. 1 arithmetic circuit 18 and second arithmetic circuit 1
9, the first calculation circuit 18 performs calculation between the viewpoint distance signal voltage Va and the positive and negative X position signal voltage V _PX of the inter-view distance adjustment circuit 22, and this output signal voltage _V Similarly to the first embodiment, the output signal voltage of the left and right image distance adjustment circuit 23 is added in the addition circuit 24.

On the other hand, in the second arithmetic circuit 19, a calculation is performed between the viewing distance signal voltage Va and the viewpoint Y position signal voltage _VPY , and this output signal voltage VY _' ' is 1/
The output signal voltages of the three-system image position adjustment circuit 28 connected to the frequency divider circuit 25 are added in the adder circuit 29, and the respective output signal voltages V _X , V _Y
It is supplied to the X-axis and Y-axis of the cathode ray tube display device 16.

Therefore, the screen on the cathode ray tube of the cathode ray tube display device 16 is divided to the left and right in 1/2 period of the transmission of ultrasonic pulses, and to the top, middle, and bottom in 1/3 of the transmission period, and one set of two screens is divided into three sections. A set of six images is synthesized on one screen in a time-division manner.

In this example, as in the case of the first example, high-speed distribution may be performed in a shorter time than the transmission of the ultrasonic pulse.

Furthermore, in the third embodiment shown in FIG. 7, images of the target object from three directions perpendicular to each other are simultaneously synthesized in a time-division manner without reducing the distant view. The output of circuit 12 is 1/
The voltage is supplied to the 3 frequency divider circuit 25, and the switching circuit 27 is operated through the switching control circuit 26 in this 1/3 cycle to add the X position signal voltage V _X and Y position signal voltage V _Y of the XY axis scanning mechanism 11 to the addition circuit 29. The outputs of the three-system image position adjustment circuit 28 are added together and supplied to the cathode ray tube display device 16.

Therefore, in this example, since the viewpoint with respect to the target object is set to an infinite distance, the arithmetic circuit is omitted, and although stereoscopic viewing of the image is not possible, the screen on the cathode ray tube of the cathode ray tube display device 16 uses ultrasonic pulses. Images from three directions are synthesized at 1/3 period of the transmission wave, and an image similar to a drawing using the first angle method or the first angle method in technical drawing is obtained, making position measurement easier. .

In addition, in the case of this example as well, high-speed time division allocation may be performed as in the case of the above-mentioned embodiment. In addition, in the above description of this example, parts that overlap with the configuration of the previous example are given the same reference numerals and the description thereof will be omitted.

In each of the above embodiments, a case has been described in which the probe 1 is scanned in a straight line with respect to the object, but the scanning of the probe 1 is not limited to the straight direction, and is conventionally performed in order to improve image quality. A compound scan may also be performed. Furthermore, the arithmetic circuit can be simplified by approximating it with an appropriate function within an allowable error range. Note that the calculation in the calculation circuit is not limited to an analog method, and it goes without saying that it may be realized by a digital method.

As described above, according to the present invention, a target object can be reproduced in an image with a reduced distant view using the ultrasonic pulse method, and can be reproduced in an image obtained by stereoscopic vision and observation from multiple directions, and the shape of the target object can be determined. This makes it extremely easy to observe the shapes and sizes of internal organs, etc. of the human body.

[Brief explanation of the drawing]

1 to 4 are explanatory diagrams for explaining the present invention, and FIG. 5 is a first diagram of an ultrasound imaging apparatus according to the present invention.
FIG. 6 is a system diagram of the second embodiment, and FIG. 7 is a system diagram of the third embodiment. In the figure, 1 is the probe, 11 is the XY axis scanning mechanism, 1
2 is a clock circuit, 13 is a wave transmitting circuit, 14 is a wave receiving circuit, 16 is a cathode ray tube display device, 17 is a sawtooth wave generating circuit, 18 and 19 are arithmetic circuits, and 21 is 1/2
22 is a distance adjustment circuit between viewpoints, 23 is a distance adjustment circuit between left and right images, 25 is a 1/3 frequency division circuit, 2
7 is a switching circuit, and 28 is a three-system image position adjustment circuit.

Claims (1)

[Scope of Claims] 1. A probe that irradiates an ultrasonic pulse to a target object, a scanning means that three-dimensionally scans the probe to the target object, and a probe that irradiates an ultrasonic pulse to the target object, In an ultrasonic imaging device comprising a receiving means for receiving a signal reflected by the probe and a display means for displaying an ultrasonic image of the object, the probe has a sawtooth shape that steps up each time an ultrasonic pulse is transmitted from the probe. A means for generating waves, a means for dividing the clock frequency by 1/2, a means for adjusting the distance between viewpoints for generating a viewpoint X position signal voltage by adding the 1/2 frequency-divided output, and a signal voltage for distributing left and right images. a first calculation means for inputting and calculating the sawtooth wave, the X position signal voltage, the viewing distance signal voltage, and the viewpoint X position signal voltage; A second circuit that inputs and calculates the Y position signal voltage, viewing distance signal voltage, and viewpoint Y position signal voltage.
and means for adding the output of the first calculation means and the output of the left and right image distance adjustment means, and the output added by the addition means and the output of the second calculation means. An ultrasonic imaging apparatus characterized in that an ultrasonic image corresponding to a viewpoint is obtained in a time-division manner by inputting the information into the display means.