JPH03173548A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To improve bearing resolution without reducing the frame number by combining multistage focusing technique with frame correlation processing technique, applying weights to a plurality of images having different focusing positions in such a manner that they are differed in depth direction to constitute one image. CONSTITUTION:When three images of a frame 0 having two-stage focusing in focusing positions 0, 1, a frame 1 having two stage focusing in focusing positions 2, 3, and a frame 2 having two-stage focusing in focusing positions 4, 5 are subjected to frame correlation processing to constitute one image, the frame correlation processing is carried out in such a manner that the frame 0 is weighted in the focusing positions 0, 1, the frame 1 in the focusing positions 2, 3, and the frame 2 in the focusing positions 4, 5 to constitute one image. Consequently, each image data of A, B, C, D, E, F can be obtained correspondingly to each focusing position 0, 1, 2, 3, 4, 5, and an image having transmission 6-stage focusing can be substantially realized while keeping the frame value corresponding to transmission two-stage focus.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention (Industrial Application Field) The present invention relates to an ultrasonic diagnostic apparatus that transmits and receives ultrasonic waves in a multi-stage focusing manner.

(Prior art) In an ultrasound diagnostic device that uses images constructed based on echo data obtained by transmitting and receiving ultrasound waves to and from a subject as diagnostic information, the depth position of the diagnostic target region within the subject is used as diagnostic information. It is equipped with a focus control function so that accurate diagnostic information can be collected by focusing the ultrasound on.

Furthermore, ultrasonic diagnostic equipment is known to be equipped with a multi-stage focus control function that applies two or more stages of focusing in the depth direction within the subject, improving azimuth resolution and S/N characteristics. It is being In order to change the focus depth position in this way, electrical signals are applied to the multiple ultrasound transducers that make up the ultrasound probe that emit ultrasound after being delayed individually via delay elements. This can be easily realized by electronic control means that controls the following.

FIG. 6 is a schematic diagram illustrating such a control method, in which delay elements 17a, 17b, 17c are connected from the pulse generator 16 so as to obtain a desired delay characteristic in advance.

By applying an electric signal to each set of transducers 18a, 18b, 18c, .
From there, focus F on the depth position. Ultrasonic waves are emitted so that the Focus F by changing the delay characteristics. can be set at any position in the depth direction. Focus F is also achieved by switching the electrical signals applied to each vibrator for each set. The position of can be moved in the direction along the transducer row.

Furthermore, FIG. 7 is a specific explanatory diagram for applying two-step focusing as an example. To explain this using an example in which sector scanning is performed using an ultrasonic probe, the period T during which a rate signal is generated is shown.
For each step, first make one scrap in the first shallow layer (N: Naar).
The ultrasonic beam is controlled so that the ultrasonic beam is focused (F), and then the second deep focus (F) is applied.
The ultrasonic beam is controlled so that the ultrasonic wave (occus) is applied. Thereafter, the ultrasonic beams are controlled for all tests by similarly applying two stages of focus to each test.

FIG. 8 shows a composite diagram of the beam pattern to which the two-stage focus is applied in this way, and a correspondingly composite sector image.

When performing ultrasound diagnosis with multi-stage focusing in this way, several rates are required to configure one rask (line) within the sector image in Figure 8, and one image (one
time T to complete the frame). is expressed as the following equation.

To=AxTRxN Here, A: number of focus stages.

TR: Route time (1/T).

N: Number of rusks in one frame image.

Further, the number of frames F is expressed as F=1/To.

(Problem to be solved by the invention) Unfortunately, in conventional ultrasonic diagnostic equipment, when trying to increase the number of focus stages to improve azimuth resolution, the number of frames decreases as is clear from the above equation. Therefore, there is a problem that the image flickers and becomes difficult to observe. For this reason, if an attempt is made to reduce the number of focus stages, the azimuth resolution will decrease.

The present invention has been made in response to the above-mentioned problems.
It is an object of the present invention to provide an ultrasonic diagnostic apparatus that can improve azimuth resolution without reducing the number of frames.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides multiple ultrasonic waves based on echo data obtained by transmitting and receiving ultrasonic waves so as to focus multiple stages on a subject. In an ultrasonic diagnostic apparatus that configures frame images of The present invention is characterized by comprising a frame correlation processing means for applying different weights to the images and composing them into one image.

(Function) For example, when applying 6-step focusing, the ultrasound is controlled so that 2-step focusing is applied to each different depth position to take 3 images, and then these 3 images are transferred in the depth direction. A single image is constructed by performing weighted correlation processing to make the images different. As a result, it is possible to obtain an image with substantially six steps of focus while keeping the number of frames at three as in the conventional case. Therefore, azimuth resolution can be improved without reducing the number of frames.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the ultrasonic diagnostic apparatus of the present invention. 1 is an ultrasonic probe that transmits and receives ultrasonic waves to and from a subject, and a large number of ultrasonic transducers are arranged in an array. It is controlled by a transmission delay circuit 3 and a reception delay circuit 4 so that focus can be applied to an arbitrary depth position based on desired delay characteristics. 2 is a transmitting/receiving circuit that applies an electric signal to the ultrasound probe 1 so that the delay characteristics are controlled by the transmitting delay circuit 3, and also amplifies the echo signal reflected from the subject and sends it to the receiving delay circuit 4. Output. 5 outputs the echo signals received by the adder circuit to the receiver circuit 6 after phasing and adding the echo signals for each signal component obtained by each vibrator based on the delay characteristics controlled by the receiver delay circuit 4. 6 is for performing various necessary processes. An A/D converter 7 converts the echo signal into a digital signal, and this digital signal is output to the input memory circuit 8. The input memory circuit 8 stores one line of echo data of the rate signal as one unit, and outputs the echo data to the write interpolation circuit 9 sequentially. The write interpolation circuit 9 is used to interpolate missing data into necessary data. 1
0 is a data weighting section and a necessary weighting circuit 10a.

10b, 10c, . . . and a weighting coefficient is stored in each circuit. This data weighting unit 10 has several types of weighting coefficients corresponding to the frames of the transmission focus position 2 images, etc., including weighting on/off signals, frame signals, and transmission stage number signals.

Appropriate values are output based on input memory read address signals and the like. This output signal is applied to the multiplication circuit 11 together with the output signal from the write interpolation circuit 9.

The signal outputted from the multiplication by the multiplication circuit 11 is applied to the frame correlation interpolation circuit 13 via the switching circuit 12, and further added to the frame memory 14 for storage. The frame correlation interpolation circuit 13 operates to perform correlation processing between the frame data already stored in the frame memory 14 and the image data that is about to be stored, and to store the data in the frame memory 14.

When a frame signal is applied, the transmission delay circuit 3 is switched by the frame signal in order to switch the transmission focus position for each frame, and a delay characteristic based on this is output to the transmission/reception circuit 2.

Figure 2 shows three frames (frame O, frame 1, and frame 2) focused in two steps at different depth positions by the weighting unit 10, and then these three frames are assembled into one frame. An example of a method for performing frame correlation processing is shown. Frame 0 is focused at depth positions 0 and 1, frame 1 is focused at depth positions 2 and 3, and frame 2 is focused in two steps at depth positions 4 and 5, respectively. a, b, c, d, and e indicate the boundaries of each focus stage. A, B, C, D.

E and F each show image data of ultrasound beams corresponding to six focus positions. Also frame 0
．． Frame 1. Each focus position of frame 2 has a weighting circuit 10a, 10b, respectively.

10c gives a coefficient of O or 3 as an example as shown.

When composing three images (frame O, frame 1, frame 2) focused at two stages at different depth positions into one image by performing frame correlation processing, each focus stage is Each item is weighted and processed as shown in the figure.

As a result, image data of A, B, C, D, E, and F are obtained corresponding to each focus position 0, 1, 2.3, and 4°5, which corresponds to two-stage transmission focus. It is possible to substantially realize an image with six transmission steps of focus while maintaining the frame value.

FIG. 3 shows a time chart when such multi-stage focus control is performed. Each frame 0, 1.2 as shown in FIG. 4 is sequentially captured every cycle of the frame signal, and each vertical position is sequentially focused in synchronization with the rate signal. Furthermore, weighting coefficients are output in synchronization with the focus position signal for each section of the frame signal.

As a result, frame O is photographed in the first frame section, frame 1 is photographed in the next frame section, and frame 2 is photographed in the next frame section. Each of these frames 0, 1.2 is weighted for each focus position and subjected to frame correlation processing, so that one image as shown in FIG. 4 is constructed.

Next, the operation of this embodiment will be explained.

As shown in Fig. 4, frame 0 has two-step focus on focus positions 0 and 1, frame 1 has two-step focus on focus positions 2 and 3, and focus positions W4 and 5.
The three images of frame 2 with two-step focus applied to are sequentially captured, and when composing these three images into one image by performing frame correlation processing, the focus position is set to 0.1 for each frame O. Frame correlation processing is performed such that for frame 1, focus positions 2 and 3 are weighted, and for frame 2, focus positions 4 and 5 are weighted. That is, one image is constructed by weighting each frame so that the depth direction is different.

As a result, as shown in Figure 5, the number of frames transmitted is 2.
Substantially transmits 6 while maintaining the value equivalent to step focus.
It is possible to compose an image with multiple focuses.

In other words, as is clear from the time chart in Figure 3,
The time for one frame is the same as in the case of two-step focusing, and an image with six-step focusing can be obtained while the number of frames F remains F'=(1/2×TRxN).

Therefore, compared to the number of frames F = (1/6xTRXN) when simply applying 6-step focusing as in the past, the same image can be obtained with three times the number of frames as shown in the following. It becomes like this. As a result, azimuth resolution can be improved without reducing the number of frames, and S/N characteristics can also be improved. Therefore, since there is no flickering when observing images, observation becomes easier and diagnostic efficiency can be improved.

Furthermore, this allows the number of transmission focus stages to be increased while maintaining the same number of frames as in the prior art, thereby further improving resolution. Furthermore, since the number of frames is faster, the images are easier to see, and the time for fixing the ultrasound probe to the subject can be shortened, reducing the burden on the operator and, in turn, reducing diagnostic time. Can be done.

The frame correlation interpolation circuit and frame memory that handle frame correlation processing are paired with blocks 15 in FIG.
By providing a plurality of images such as A and 15B and switching to an arbitrary image using a switching circuit, it becomes possible to arbitrarily take out each image whose focus position differs depending on the depth position and display it individually.

In this embodiment, an example has been described in which three images with two-stage focus are configured into one image, but the number of focus stages and the number of images can be set arbitrarily. Furthermore, the target image is not limited to a normal tomographic image (B-mode image), but can also be applied to a color image. Further, the circuit configuration is not limited to this.

[Effects of the Invention] As is clear from the above description, according to the present invention, a multi-stage focusing technique and a frame correlation processing technique are combined to combine a plurality of images with different focus positions into a single image by weighting them differently in the depth direction. Since the images are configured as follows, the azimuth resolution can be improved without reducing the number of frames.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the ultrasonic diagnostic apparatus of the present invention, FIG. 2 is an explanatory diagram of the frame correlation processing method according to the present embodiment, and FIG. 3 is a timing chart explaining the operation of the present embodiment. Fig. 4 shows sector patterns of three types of images to be subjected to frame correlation processing, Fig. 5 shows sector patterns showing images subjected to frame correlation processing, Fig. 6 is a schematic diagram of a conventional focus control method, and Fig. 7 shows a conventional method. FIG. 8 is a timing chart illustrating the multi-stage focus control method in the example, and is an explanatory diagram of an image obtained by the conventional example. 3... Transmission delay circuit, 4... Reception delay circuit, 8... Input memory circuit, 9... Write interpolation circuit,
10...Data weighting unit, 11...Multiplication circuit, 1
3...Frame correlation interpolation circuit, 14...Frame memory.

Claims (1)

[Claims] In ultrasonic diagnostic equipment that constructs multiple frame images based on echo data obtained by transmitting and receiving ultrasonic waves in a multi-step focusing manner to the subject, each frame has a different depth position within the subject. and a focus control means that applies different weights in the depth direction to each image focused on different depth positions.
1. An ultrasonic diagnostic apparatus comprising: frame correlation processing means for configuring into a single image.