JPS6145455B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasound probe used in an ultrasound imaging device.

BACKGROUND ART Conventionally, when obtaining a tomographic image of a subject using an ultrasonic imaging apparatus, the scanning method of an ultrasonic beam from a probe can be roughly divided into a linear scanning method and a sector scanning method. Although the sector scanning method is suitable for chest imaging, it has the following disadvantages compared to the linear scanning method.

(1) In the electronic sector scanning method, (a) the electronic circuitry is enormous and complicated, so the cost of the entire device is high;

(b) When attempting to scan sectors up to a large deflection angle, it is difficult to obtain a good quality image due to the lack of sensitivity of the vibrator at large angles.

(2) In the mechanical sector scanning method, (a) the ultrasonic transducer is moved by a motor, etc., so the overall shape of the probe is large.

(b) Cannot be scanned in any order.

(c) Scanning speed is slow.

In view of these points, it is an object of the present invention to provide an ultrasonic probe with a simple structure that performs linear electronic scanning on the transducer and sector scanning on the subject. shall be.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 and FIG. 2 are explanatory main part configuration diagrams showing one embodiment of the ultrasonic probe according to the present invention,
FIG. 1 is a plan view, and FIG. 2 is a side view thereof. In the figure, 10 is a linear electronic scanning probe, 20 is a linear sector conversion lens, and 30
indicate the propagation medium, respectively. The linear electronic scanning probe 10 includes a transducer group 11 formed by arranging a plurality of transducers (for example, PZT) in a straight line, and sequentially scans a plurality of adjacent transducers as one group to generate ultrasonic waves. It is used for sending and receiving data. The linear sector conversion lens 20 is an acoustic lens having one end 21 formed in a planar shape and the other end surface 22 opposite to this end surface 21 formed in a curved shape. An end surface 21 of this lens 20 is joined to the vibrator group 11. Note that the end face 21 and the vibrator group 11
A matching layer having the purpose of achieving acoustic impedance matching may be interposed between the two. The lens 20 has a focal point at the center of the open end surface 32 of the propagation medium 30.

Note that the focal point position does not necessarily have to match the position of the opening end surface 32.

The shape of the curved surface 22 of such a lens is formed into an inertia circular curve that satisfies the following equation with respect to the x-axis and y-axis as shown in FIG.

Here, f is the focal length, V ₁ is the sound velocity in the lens 20, and V ₂ is the sound velocity in the propagation medium 30.

Note that the curved surface 22 is not necessarily limited to the above-mentioned inertia circular curve, but a circular arc curved surface that is easy to manufacture is also substantially sufficient. The radius R of the circle in this case
If the aperture of the lens 20 is sufficiently smaller than the focal length f, then the following equation R obtained by approximation from equation (1) can be applied.

R=f(1-V ₂ /V ₁ ) Furthermore, when the aperture of the lens 20 is even larger, a circular arc curve that most closely approximates equation (1) within the aperture of the lens 20 may be applied. Such a lens 20 can be made of, for example, acrylic resin.

The propagation medium 30 guides the ultrasonic waves from the lens 20 to the aperture end surface 32, and conversely introduces the ultrasonic waves entering from the aperture end surface 32 into the lens 20, and is made of rubber, rubber-like material, or water with low propagation loss. ,
It is composed of gel or the like. However, water,
Naturally, when it is composed of a fluid such as gel,
For example, water, gel, or the like is sealed in a hollow container made of a material that does not allow fluids to pass through, such as an acrylic resin plate. A surface 31 of the propagation medium 30 facing the open end surface 32 is formed in the same shape as the curved surface 22 of the lens 20 and is joined to the curved surface 22. The opening end surface 32 is formed into a flat or curved shape. Although this propagation medium 30 has a fan-like configuration with linear side surfaces 33, the side surfaces 33 are not limited to a linear shape and may be curved outward. Furthermore, in this case, it is desirable that the opening end surface 32 be a thin film, considering that it is a portion that is coupled to the subject 40. The thickness of this thin film is preferably sufficiently thinner than the wavelength of the ultrasonic wave in order to prevent the generation of false images due to the thin film. Note that an acoustic lens may be externally attached to the opening end surface 32 to narrow down the ultrasonic beam.

Note that the other side surfaces of the lens 20 and the propagation medium 30 are formed into a substantially planar shape as shown in FIG.

FIG. 4 shows the state of scanning with the ultrasonic probe having such a configuration. That is, group G _i
The ultrasonic beam B _a generated by simultaneously exciting the transducers of
After passing straight through the linear sector conversion lens 20, the light beam passes through the propagation medium 30 while converging toward the focal point P _f at the center of the aperture end surface 32. Furthermore, the opening end surface 3
The ultrasonic waves emitted from 2 go straight into the subject 40 without hitting the ribs 41. On the other hand, when the vibrators of group G _j are simultaneously excited, beam B _b is emitted into the subject in the same manner as described above. These beams B _a and B _b always pass through the focal point P _f , and as is clear from the figure, when linear electronic scanning is performed on the transducer group 11, sector scanning is performed on the object 40. I can understand that.

FIG. 5 is a diagram showing the state of the beam when the vibrator is driven in a delayed manner. In FIG. 4, the transducers are driven simultaneously, but in the case of FIG. 5, the transducers in the group are each driven with an appropriate time delay so that the ultrasonic beam emitted from the transducers spreads. As a result, the focal position of the lens 20 and the beam focal position no longer match, but the beam width within the subject becomes narrower than in the case of FIG. 4, resulting in the effect that a tomographic image with good resolution can be obtained.

Note that the acoustic impedance of the probe 10 is generally larger than the acoustic impedance of the subject. Therefore, in order to guide the power of the probe to the subject with as little loss as possible, it is desirable to select the respective acoustic impedances as follows.

I _P I _L I _M I _Bwhere I _P is the acoustic impedance of the probe 10, I _L is the acoustic impedance of the lens 20,
I _M is the acoustic impedance of the propagation medium, and I _B is the acoustic impedance of the object.

As explained above, according to the present invention, with a simple configuration, ultrasonic waves can perform linear-sector conversion, which is linear electronic scanning for the transducer, but high-quality sector scanning for the object. A probe can be realized.

Furthermore, if the ultrasound probe of the present invention is used, sector scanning suitable for chest imaging etc. can be performed using a simple and inexpensive linear electronic scanning circuit without requiring a complicated and expensive electronic circuit to swing the ultrasound beam. There are effects that can be achieved. Furthermore, if we focus on the vibrator, since the ultrasonic beam enters and exits almost in front of the vibrator, sector scanning can always be performed in the direction of maximum sensitivity for the vibrator, which has a unique effect not seen in conventional sector scanning.

[Brief explanation of the drawing]

Fig. 1 is an explanatory main part configuration diagram showing an embodiment of an ultrasonic probe according to the present invention, Fig. 2 is a side view of the probe shown in Fig. 1, and Fig. 3 is a linear sector conversion lens. FIGS. 4 and 5 are diagrams for explaining the structure of the linear sector conversion operation. 10...Linear electronic scanning probe, 11...
Oscillator group, 20... linear sector conversion lens,
30...Propagation medium.

Claims (1)

[Scope of Claims] 1. A vibrator group consisting of a plurality of vibrators arranged in a straight line, one end surface is formed into a flat shape, and the other end surface opposite to this surface is thinner as it approaches the center. A linear sector conversion lens formed into a curved surface is bonded so that its planar end surface faces the vibrator group, and has an aperture end surface formed in a planar or curved shape and faces this aperture end surface. A propagation medium formed into a curved surface whose other surface coincides with the curved surface of the linear sector conversion lens is bonded so that the curved surface faces the curved surface of the linear sector conversion lens, and the vibrator group is An ultrasonic probe characterized in that it is capable of emitting a sector-scanning ultrasonic beam from an aperture end face by performing linear scanning. 2. The ultrasonic probe according to claim 1, wherein the curved surface of the linear sector conversion lens is formed into an elliptic curve. 3. The ultrasonic probe according to claim 1, wherein the curved surface of the linear sector conversion lens is formed into an arc shape. 4. The ultrasonic probe according to claim 1, 2, or 3, characterized in that the opening width of the opening end face of the propagation medium is shorter than the length of the curved surface. 5. Claim 1, characterized in that the position of the focal point of the linear sector conversion lens and the position of the aperture end face of the propagation medium are arranged to match.
Ultrasonic probe as described in section. 6. The ultrasonic probe according to claim 1, characterized in that the propagation medium is rubber or a rubber-like material with low propagation loss of ultrasonic waves. 7. The ultrasonic probe according to claim 1, wherein water or a gel-like medium is mainly used as the propagation medium. 8. The ultrasonic probe according to claim 7, wherein the open end face of the propagation medium is made of a material with a thickness thinner than the wavelength of the ultrasonic wave.