JPS59174150A - Multi-focus ultrasonic diagnostic apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multifocal ultrasound diagnostic apparatus configured to focus sound beams generated from an array transducer in the thickness direction.

Conventionally, an ultrasonic diagnostic apparatus using a linear array probe formed by arranging several transducers TDI to TDn in a straight line is well known. There is also a method in which the beam generated from the probe is focused in a direction perpendicular to the Louis arrangement direction, so-called slice thickness direction, to improve the resolution in the slice direction.

As a method of focusing the beam in the slice direction,
Usually, a method of focusing using an acoustic lens ti is adopted.

However, in this method, the focal length of the lens is fixed at a certain point, so the beam width narrows near the focal point but suddenly widens before and after the focal point. , as shown in Fig. 1, the eye oscillator 'rD l... is also divided in the thickness direction to form a two-dimensional array, and the number of aperture elements or the aperture width in the thickness direction is adjusted to the diagnostic depth. There are ways to respond and change.

However, when using this method (the acoustic lens has a fixed focus) to generate ultrasonic waves with a small aperture for short distances and a large aperture for long distances, the beam width will be as shown in Figure 2. For small apertures, solid line A1 and for large apertures, solid line B shows a problem. However, there was a problem in that a sufficiently narrow beam width could not be obtained from a short distance to a long distance.

In view of these points, the object of the present invention is to provide a multifocal ultrasound diagnostic device that has good resolution in the thickness direction over a wide range of diagnostic depths.

The present invention will be described in detail below using the drawings. FIG. 3 shows an embodiment of the present invention, which differs from the one in FIG. 1 in that the acoustic lens is multifocal. That is, the acoustic lens L21 in FIG. t, has a curvature distribution such that the focal length changes depending on the aperture width. To explain in more detail, the curvature is reduced at the center of the lens to shorten the focal length, and the curvature is increased toward the outside of the lens to lengthen the focal length.

As shown in Figure 2, the beam width from a probe with this configuration is as shown at point t4Ia for a small aperture and as a dotted line for a large aperture, which is narrower than the solid lines A and H in the conventional case. ing.

Note that the number of divisions of the aperture and focal length may be increased in multiple stages to provide a multifocal point. In addition, the resonator to which the present invention is directed is not limited to the linear type as described above, but also an annular type.
It can also be applied to arrays.

The aperture of a probe such as B is controlled in relation to the transmission and reception of waves from the main body side of the ultrasonic diagnostic apparatus (not shown).

As explained above, according to the present invention, the aperture width in the thickness direction of the vibrator is made variable, and the acoustic lens bonded to the front surface is made of a multifocal type, so that the transmitted and received wave beams are focused at a short distance with a small aperture. Since the large aperture is designed to focus over a long distance, it is possible to obtain high-quality images with good resolution in the thickness direction over a wide diagnostic depth.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a conventional probe, FIG. 2 is a diagram showing the relationship between the diagnostic depth of the transmitted and received ultrasound beam and the beam width in the thickness direction, and FIG. FIG. 1 is an embodiment configuration diagram showing an example of a probe of a multifocal ultrasound diagnostic apparatus. .

Claims (1)

[Claims] The focal length of the acoustic lens for focusing sound waves installed in the sound wave emission direction of the arrayed ultrasound probe is changed according to the elements of the eye, and the number of array elements that form one ultrasound beam is selected. A multifocal ultrasound diagnostic device in which the aperture is changed depending on the size of the aperture, and a large aperture has a larger focal length than a small aperture.