JPS6216386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic imaging device.
In a B-mode ultrasound imaging device using an electronic scan pulse echo method using a transducer array,
In order to improve the image resolution, it is necessary to narrow the directivity width of the ultrasound beam. Conventionally, the focusing of sound waves in the thickness direction of the probe (direction perpendicular to the scanning direction and the direction of sound wave propagation) was performed using a cylindrical acoustic lens provided in front of the transducer array. The focusing is performed by a phased array method using a plurality of adjacent vibrator groups.

Generally, it is necessary to widen the aperture to improve the focusing effect of ultrasound and obtain a narrow beam, but widening the aperture causes the following problems.

(1) When the aperture in the scanning direction is widened, the number of transducer elements required to synthesize one ultrasonic beam increases, and the transducer element selection circuit and delay synthesis circuit become complicated.

(2) Regarding the directivity in the scanning direction, since the spacing between the transducers that make up the array is finite, the side rope is larger than that of an acoustic lens.

The present invention improves the drawbacks of the above-mentioned conventional examples and provides an ultrasonic imaging device that can obtain clear tomographic images with a simple structure.

FIG. 1 is a diagram showing the principle of a probe section used in the ultrasonic imaging apparatus of the present invention. In FIG. 1, 11 to 1n are tanzaku-shaped vibrators made of a material such as lead zirconate titanate (PZT). Reference numeral 1 denotes a vibrator array in which the vibrators 11 to 1n described above are arranged linearly or curved. 2 is a convex cylindrical acoustic lens arranged in front of the transducer array 1 as shown in FIG. This cylindrical acoustic lens 2 is arranged in the thickness direction, that is, in the first direction.
It has the effect of converging sound waves spreading in the Z-axis direction shown in the figure, and is made of, for example, silicone rubber. 3 is a convex cylindrical acoustic lens (hereinafter simply referred to as a lens) as shown in FIG. 1, and is placed in front of the lens 2. This lens 3 has the effect of focusing sound waves spreading in the scanning direction, that is, the X-axis direction shown in FIG. 1, and is made of a material such as silicone rubber, for example. f ₁ to f _o represent focal points of ultrasound waves; for example, the ultrasound beam transmitted by the transducer 11 is focused at point f ₁ .

The operation of the contact shown in FIG. 1 constructed in this manner will be described below. In an ultrasound imaging device, in general, to obtain an ultrasound beam from a transducer array,
A single ultrasonic beam is obtained by driving a plurality of adjacent transducers in a temporal relationship, but in the probe according to the present invention, one ultrasonic beam is obtained by driving a single transducer. Get a sound beam. For example, when the vibrator 15 shown in Figure 1 is driven, the sound waves passing through the centers of lenses 2 and 3 (not the mechanical center, but the acoustic center) go straight without being refracted, as shown in l ₃ in Figure 1. do. Furthermore, the two ultrasonic waves transmitted from the transducer 15 that do not pass through the centers of the lenses 2 and 3 are denoted by l ₁ and l ₂ . Ultrasonic wave l ₁ as shown in Figure 1
After passing through the lens 2, the and l ₂ are changed in their course so that they converge in the thickness direction. Further, after passing through the lens 3, the course is changed in the direction of convergence in the scanning direction and converged at the convergence point _f5 . Similarly, the ultrasonic waves transmitted from the transducer 1K are focused at a focusing point f _k . In FIG. 1, the point focused in the thickness direction by the lens 2 is also set to be the focal point _fk .
In this manner, the probe shown in FIG. 1 can focus the ultrasonic waves transmitted from the transducer array 1 at a point at a distance A from the lens 3.

In FIG. 1, for the purpose of explaining the operation, a space C between the transducer array 1 and the lens 2 and a space B between the lenses 2 and 3 are shown as mere spaces. However, in the actual probe configuration,
These two spaces B and C are replaced by acoustic coupling means, and spaces B and C do not exist.
That is, the portions corresponding to the spaces B and C are provided with a material (for example, water) that attenuates the ultrasonic waves little and does not cause reflection at the interface with the lenses 2 and 3. Another means for filling spaces B and C is shown in FIG.

Figure 2 shows the transducer 1 and lens 2 that make up the probe.
3, but as shown in FIG.
By increasing the width in the Y-axis direction of the space B
This shows a means to fill in C and C. However, in this case, it is necessary to select materials for the lenses 2 and 3 so that the speed of sound propagating inside the lenses 2 and 3 is different.

FIG. 3 is a diagram showing an embodiment of the ultrasonic imaging device according to the present invention and a state in which a human body is examined using this device. In FIG. 3, numerals 1 to 3 indicate the probes explained in FIG. 1, and the same numbers as those of their constituent elements are given, and redundant explanation will be omitted. Reference numeral 4 denotes a scanning switch for switching transmission and reception of waves of each of the vibrators 11 to 1n. 5 is a transmitting/receiving circuit with vibrators 11~
A drive signal is applied to the oscillator 1n, and an ultrasonic echo signal received by the transducer is input and transmitted to the next stage amplification detector. 6 is an amplification detector which amplifies and detects the signal input from the transmitter/receiver circuit 5. 7 is a cathode ray tube on which an ultrasonic tomographic image is displayed. 8 is a control circuit for switching the scanning switch 4 and the cathode ray tube 7.
It is used to synchronize the control of the

The device thus constructed in FIG. 3 operates as follows. In addition, in Fig. 3, 9 is the human body, 10
indicates an organ. The control circuit 8 and the transmitting/receiving circuit 5 sequentially excite the transducers 11 to 1n via the scanning switch 4, and transmit ultrasonic waves. For example, vibrator 1K
As explained in FIG. 1, the ultrasonic waves transmitted from the ultrasonic wave are refracted so as to be focused in the thickness direction by the action of the lens 2, and further refracted so as to be focused in the scanning direction by the action of the lens 3. Focus point f
Focus at _k . FIG. 3 shows a typical path of ultrasonic waves transmitted from the transducer array. That is, only the ultrasonic waves passing through the center 0 of the lens 3, which has the effect of focusing the ultrasonic waves in the scanning direction, are shown. The ultrasound transmitted from the transducer 1K is reflected at a point P ₁ of the organ 10 and further reflected at a point P ₂ , and the ultrasound echo returns in the opposite direction along the path from which it entered and is received by the transducer 1K. Ru. Thereafter, the signal is displayed on the cathode ray tube 7 as an image signal by the transmitter/receiver circuit 5, amplification detector 6, and control circuit 8. FIG. 4 is a diagram showing the reflected and returned ultrasonic echo signals as described above over time. In FIG. 4, A indicates a transmitted pulse, and B indicates a received echo. That is, an echo from point P ₁ is received a certain time T ₁ after the transmission pulse is emitted, and an echo from point P ₂ is received further after time T ₂ .

FIG. 5 is a diagram showing an example of an image displayed on the cathode ray tube 7 as a result of the above-described scanning. In FIG. 5, the dotted line f in the center indicates the point where the transmitted ultrasonic waves are focused. That is, in the section L1, the image is in focus as shown in FIG. 5, and as the distance from the dotted line f increases, the image becomes blurred in the sections L2 and L3.

In the above description, the configuration of the probe includes a lens 2 that focuses sound waves in the thickness direction on the front surface of the transducer array 1, and a lens 3 that focuses sound waves in the scanning direction on the front surface of this lens 2. As described above, the present invention can also be achieved even if the positions of lenses 2 and 3 are interchanged. That is, a lens 3 that focuses sound waves in the scanning direction may be provided on the front surface of the transducer array 1, and a lens 2 that focuses sound waves in the thickness direction may be provided on the front surface of this lens 3.

Further, although the lenses 2 and 3 shown in FIGS. 1 to 3 are arranged with the convex sides of the lenses facing the subject, this description does not limit the combinations of lens orientations.

Further, in the above description, the lenses 2 and 3 were described as being configured separately, but the present invention can also be realized even if these two lenses are combined to form a single lens. That is, an example is shown in FIGS. 6 and 7.

FIG. 6 is a diagram showing a single lens having a convex lens shape both in the thickness direction (YZ cross section) and in the scanning direction (XY cross section).

FIG. 7 is similar, but the orientation of the convex lens in the thickness direction and scanning direction is different from FIG. 6.

In this way, the present invention uses one transducer for transmitting one ultrasonic beam, and the shape of this transducer is arranged in a tanza, so that the transducers are arranged in a straight line or curved shape, and By providing a cylindrical acoustic lens that focuses sound waves in the direction and a cylindrical acoustic lens that focuses sound waves in the scanning direction, or by providing a cylindrical acoustic lens that focuses sound waves in the thickness direction and the scanning direction simultaneously, the conventional ultrasonic This is an improvement over the drawbacks of sonic imaging devices. That is, according to the present invention: (1) Since the ultrasonic beam is focused only by the cylindrical acoustic lens without using the phased array method, the electric circuit of the ultrasonic imaging device can be significantly simplified.

(2) Since focusing is performed using a cylindrical acoustic lens rather than a phased array method, ultrasonic waves with small side lobes can be obtained, and as a result, clear tomographic images can be obtained.

(3) Since a tanzaku-shaped transducer with a relatively large area can be used, the sensitivity of ultrasonic transmission and reception can be increased, and as a result,
A tomographic image with better image quality can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the probe section used in the ultrasonic imaging device of the present invention, FIG. 2 is a diagram showing another embodiment of the probe shown in FIG. 1, and FIG. A fourth diagram showing an embodiment of the ultrasonic imaging device according to the invention and a state in which a human body is examined using this device.
The figure is a time chart of ultrasonic echoes, Figure 5 is a diagram showing an example of an image obtained on a cathode ray tube according to the present invention, and Figures 6 and 7 are diagrams showing an example of the lens used in the present invention. . 1 to 1n... vibrator, 1... vibrator array,
2, 3...lens, 4...scanning switch, 5...
Transmission/reception circuit, 6...amplification detector, 7...braun tube, 8...control circuit.

Claims (1)

[Claims] 1. A transducer array in which tanzag-shaped transducers are arranged in a straight line or in a curved line, and a first cylindrical acoustic lens provided in front of the transducer array to focus ultrasonic waves in the thickness direction. and a second cylindrical acoustic lens provided in front of the first cylindrical acoustic lens to focus the ultrasonic waves in the scanning direction; An ultrasonic imaging device using an electronic scan type pulse echo method, characterized in that a sonic echo signal is displayed on a cathode ray tube after passing through a transmitting/receiving circuit and an amplification detector. 2. A transducer array in which tanzag-shaped transducers are arranged in a straight line or in a curved line; a second cylindrical acoustic lens provided in front of the transducer array to focus ultrasound in the scanning direction; A first cylindrical acoustic lens provided on the front surface of the cylindrical acoustic lens to focus ultrasonic waves in the thickness direction, and a circuit for transmitting and receiving ultrasonic echo signals obtained through each of the vibrators and the first and second cylindrical acoustic lenses. An ultrasonic imaging device using an electronic scan type pulse echo method, characterized in that the image is displayed on a cathode ray tube after passing through an amplified detector. 3. A transducer array in which tanzag-shaped transducers are arranged in a straight line or in a curve, a cylindrical acoustic lens provided in front of the transducer array to simultaneously focus ultrasonic waves in the thickness direction and the scanning direction, and each of the above-mentioned vibrations. 1. An ultrasonic imaging device using an electronic scan pulse echo method, characterized in that an ultrasonic echo signal obtained through a cylindrical acoustic lens and a cylindrical acoustic lens is displayed on a cathode ray tube after passing through a transmitter/receiver circuit and an amplification detector.