JPH0131901B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a probe for an ultrasonic diagnostic apparatus that detects in-vivo information easily and at high speed from within a body cavity.

Conventionally, most ultrasonic diagnostic devices emit ultrasonic pulses into the body from the body surface and receive the reflected waves to obtain in-vivo information. In addition, there are tests for prostate diagnosis by inserting an ultrasound probe into the rectum, and tests from within the body cavity, in which a probe attached to the tip of a catheter is inserted into the aorta or heart. The law is known.

Figure 1 shows a probe using the PPI method, which is used for prostate examinations, etc. It consists of a disk vibrator 2 attached to the side of the tip of a rod 1.
Ultrasonic pulses are emitted from the oscillator, and reflected waves from prostate tissues are detected using the same transducer, and the tip is covered with a water bladder 4 filled with water. As it is, the ultrasonic beam is only in one direction, so the support rod 5 with the probe attached is rotated in the direction of the arrow, and the signal from the signal line 7 is output according to the rotation angle detected by the potentiometer 6. By displaying , a cross-sectional image on the circumference can be obtained. However, in this case, since the rotation is performed mechanically, the mechanism is complex and large, and high-speed rotation is not possible, so cross-sectional images cannot be obtained unless using a display with a memory function or photography.
Further, the part of the rectum into which the probe is inserted is not necessarily straight, and if the support rod of the probe is made flexible and rotated, a more complicated mechanism is required. Therefore, with this method, it is impossible to direct the probe or support rod in any direction.

On the other hand, although the application is different, electronic scanning is performed instead of the mechanical rotation of the probe shown in Figure 1, in which a large number of transducer elements are arranged at the tip of a catheter, and the catheter is inserted into the heart. A method for obtaining an image of a cross section perpendicular to the axis of the probe has been announced, and FIG. 2a is a perspective view of a probe of this example. In this example, a large number of transducer elements 9 are arranged around the catheter 8, so if the number of transducer elements is increased, the width of the transducer element 9 becomes narrower, making it difficult to manufacture.On the other hand, if this width is increased, the vibration As the number of child elements 9 decreases, side lobes are more likely to occur, and scanning lines become coarser.

In this method, as shown in the cross-sectional view of Fig. 2b, the transducer element 9' is operated in the direction A in which the ultrasonic beam is to be emitted, and the same operation is repeated while shifting the elements one by one. ,
The ultrasonic beam is scanned in the radial direction B. However, in this system, in addition to an electronic switch for switching the elements, a delay circuit is required just to align the wavefronts of the ultrasonic pulses emitted from each element, making the circuit complex. Furthermore, since the transducer element 9' involved in emitting the ultrasonic beam actually has a finite width,
The elements themselves have directivity, and the surface orientation of each element varies with respect to the direction in which ultrasonic waves are to be emitted, making it difficult to obtain a sound field with small side lobes and sharp directivity.

An object of the present invention is to provide a probe suitable for an ultrasonic diagnostic apparatus that can obtain in-vivo information easily and at high speed from inside a body cavity.

In the present invention, we focus on the fact that a parallel image is more suitable for electronic scanning than a cross-sectional image perpendicular to the catheter as used in the conventional probe for intracorporeal examination,
An elongated transducer element is fixed to the side surface of a cylindrical support so that its length direction is approximately perpendicular to the central axis of the cylindrical support, and each transducer element is given a delay time or a switch or By doing both and scanning the ultrasonic beam in a plane that includes the central axis of the support,
This makes it possible to obtain in-vivo ultrasound tomographic images from inside the body cavity at high speed and easily.

Examples of the present invention will be described below. FIG. 3a is a front view of the tip of this embodiment, and FIG. 3b is a sectional view taken along line AA. The side surface of the tip of the cylindrical support 12 of the probe 11 is hollowed out and filled with an ultrasonic absorber 13 having a flat surface. Furthermore, a plurality of elongated transducer elements 14 are arranged on the surface of this ultrasonic absorber. This vibrator element 14 is fixed in a direction perpendicular to the center of the support 12. Each transducer element 14 has
A lead wire 15 that sends a reflected wave signal to a signal processing device (not shown) to which a driving pulse is applied or which is received.
are connected through the support 12.

Voltage pulses are applied to these individual transducer elements 13 in a predetermined manner to emit ultrasonic pulses, and the reflected waves of the ultrasonic pulses are received by the same transducer elements and converted into electrical pulses. Take it out as a signal.

In this case, the ultrasonic beam can be scanned by the method of driving each transducer element.

Ultrasonic beam scanning methods include sector (fan-shaped) scanning and linear scanning, and sector scanning will be explained here.

FIG. 3C is a drawing of only the vibrator element 13 portions a and b. Let the interval between each element be d, and the element number be 1, 2,...n. Now, a voltage pulse is applied to the nth element, then a voltage pulse is applied to the (n-1)th element after a delay of t _d = dsinθ/c, and then t _d
If a predetermined delay time is given to drive each element by applying the (n-2)th elemental voltage pulse with a delay of = dsinθ/c, the wavefront of the ultrasonic pulse becomes w in Figure 3C. The ultrasonic beam is deflected by θ with respect to the direction perpendicular to the transducer surface. Here, c is the propagation speed of the ultrasonic wave. The emitted ultrasonic pulse is reflected from a reflector inside the body, and the reflected pulse can be received by the same element, but by giving the received signal exactly the same delay time as for transmission and then adding it together, the reflected pulse can be reflected in the θ direction. can be given sharp directivity.
By changing the value of t _d here, the ultrasonic beam can be scanned in a fan shape within a plane including the central axis of the cylindrical support.

According to the present invention, a probe can be inserted into a body cavity, such as a rectum, an esophagus, or a uterus, and a tomographic image of a living body's tissues can be easily obtained in real time. 60-30 per second
It is easy to obtain frame images on a cathode ray tube, eliminating the inconvenience of having to use a display device with a memory function or take a photograph to obtain a tomographic image.

In addition, since there are no mechanically moving parts, it is safe and easy to handle, and a cross-sectional image including the central axis of the cylindrical support can be obtained.By rotating the support, the scanning plane can be freely selected, and the 3D You can get information. Furthermore, since it can also capture movement, it has diagnostic capabilities that are not possible with conventional PPI methods.

On the other hand, when compared with the conventional radial method as shown in Figure 2, there is no need to electrically switch each element, and scanning is possible by sequentially applying time differences at equal intervals to each element. It's easy. Also, at that time, all of the elements are activated, the direction of the ultrasonic beam is the same with respect to the surface of each element, and the contribution of each element is approximately equal. Therefore, by simple control, side lobes can be minimized. It can emit and receive sharply directional ultrasound beams.

In addition, n transducer elements are arranged in the axial direction of the support, and even if this cylindrical support is made thinner to some extent, the number n of transducer elements can be sufficiently increased, so it is possible to obtain a large number of transducer elements when the ultrasonic beam is deflected at a wide angle. It has the advantage that a sufficiently large effective aperture can be taken and sufficient resolution can be obtained.

Since the method of the present invention does not require any special mechanical parts, the vibrator element can be made flexible and thin. FIG. 4a shows another embodiment of the present invention, in which a flexible tube 23 covering a slightly thicker probe section 20 and a cable 22 connected to a transducer element 21 is shown. It has the following structure.

In FIG. 5, a cover 25 such as a thin rubber film is placed over the outside of the probe section 24, and a liquid 26 such as water is injected into the cover 25 so that the amount can be controlled. This embodiment has the effect of preventing gas from entering between the inner wall of the body cavity and the probe, and improving acoustic coupling. Moreover, since the ultrasonic waves are transmitted and received while being deflected, a field of view wider than the length of n transducer elements can be provided. In other words, the probe for testing inside a body cavity cannot be enlarged because it is inserted into the body cavity of a living body. but,
In the present invention, even if the length of the array of transducer elements is not long, a wide field of view can be obtained because the ultrasonic waves are deflected.

Although the method described above is sector scanning, the present invention can also be applied to linear scanning. Linear scanning is possible if the method shown in Fig. 3 is to connect several vibrator elements, for example, drive them in M sets, shift one element, and then drive M units again, and in this case also, the axis of the support By rotating the support, any cross section including the rotation axis can be easily obtained, similar to sector scanning. In both sector scanning and linear scanning, the above example describes a method of controlling the wavefront so that it becomes a plane perpendicular to the direction of travel of the ultrasonic beam, but a slight delay time is added to focus it on the desired point. Of course, this is also possible. Further, the present invention can also be applied to a compound method that is a mixture of a sector method and a linear method.

As described above, according to the present invention, the side surface of the tip of the cylindrical support is hollowed out, an ultrasonic absorber with a flat surface is provided in this part, and the longitudinal direction is supported on the surface of the ultrasonic absorber. Since the transducer element is arranged perpendicular to the central axis of the body, it is possible to use a transducer element that is longer than in the case where the transducer element is placed on the surface of the cylindrical body, that is, a transducer element with strong ultrasonic power can be used.

In addition, since a semicylindrical acoustic lens that narrows the ultrasonic beam in the length direction of the transducer element can be placed in this hollowed out part, this acoustic lens protrudes beyond the surface of the support before hollowing out, making it easier to operate. It won't get in the way.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a device using the conventional PPI method.
Fig. 2 shows a conventional example in which transducer elements are arranged at the tip of a catheter to perform electronic radial scanning, Figs. Figure 3c is a diagram for explaining the method of performing sector scanning according to the present invention, Figure 4 is a diagram showing one embodiment of the present invention using a flexible tube as a support, and Figure 5 is a diagram showing another embodiment. be. DESCRIPTION OF SYMBOLS 11... Probe, 12... Support body, 13... Ultrasonic absorber, 14, 21... Vibrator element, 15... Lead wire, 20, 24... Contact portion, 22... Cable, 23... Flexible tube.

Claims (1)

[Claims] 1. A cylindrical support, an ultrasonic absorber with a flat surface embedded in the hollowed out part of the tip side of the support, and a surface of the ultrasonic absorber with the center of the support in the longitudinal direction. A probe for intracorporeal examination characterized by comprising a plurality of transducer elements arranged perpendicularly to the axis and transmitting and receiving ultrasonic waves, and a conductive wire connected to the transducer elements to guide electrical signals. Tentacles.