JP2866972B2 - Ultrasound diagnostic equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus, and in particular, changes a sound field scanning mode according to a change in display magnification, and applies the same to scanning with different display magnifications. The present invention relates to an ultrasonic diagnostic apparatus capable of displaying images.

(Prior Art) An ultrasonic diagnostic apparatus is an apparatus that irradiates an object with ultrasonic waves and forms a tomographic image with a reflected wave from a reflector in the object to make a diagnosis. The scanning method of this ultrasonic diagnostic apparatus includes mechanical scanning, manual scanning, and electronic scanning, but electronic scanning is superior in terms of freedom of scanning, small size, light weight, and many other points.
Recently, an electronic scanning system has been mainly used. This electronic scanning type ultrasonic diagnostic apparatus uses a switched array type ultrasonic probe, and electronically controls the width of a sound ray, the depth of focus, the direction of the sound ray, and the like.
FIG. 6 shows the shape of the sound ray and the display screen when the display magnification is changed in such a switched array type ultrasonic diagnostic apparatus. The figure shows an example in which the display magnification is 0.7, 1, and 1.4 times the FOV (visible area). The display magnification of 0.7 means that the horizontal length of the display screen is 0.7 times the depth of the sound ray. FIG. 6 (a) shows that the display magnification is 0.
Figures showing the depth of focus of 7 times, 1 time, and 1.4 times, and (b) shows the display screen for each depth of focus in (b). Is displayed with a reduced horizontal length. In the figure, reference numeral 1 denotes a switched linear array type ultrasonic probe for irradiating an ultrasonic signal. A, B, and C have display magnifications of 0.7x, 1x,
This is the shape of the sound ray when the magnification is 1.4 times. Reference numeral 2 denotes a display screen for displaying an echo based on an ultrasonic signal obtained by scanning each sound field shown in (a), and shows a case where an image having a display magnification of 1.4 is displayed on the entire display screen 2. In the figure, the range indicated by the broken line is the image range A 'when the magnification is 0.7, and the range indicated by the dashed line is the image range B' when the magnification is 1;
The image range C ′ of 1.4 is the range of the solid line which is the full range of the display screen 2. In the ultrasonic apparatus that performs the switched array linear scan, when the display magnification is changed to display the image at a deep depth, when the display magnification is small, the display on the display screen 2 has a narrow width. This is because, as is apparent from the figure, the sound ray becomes a vertically elongated strip shape.

(Problems to be Solved by the Invention) Such a rectangular shape is unavoidable because the scanning width on the sound field side is constant, but it may be very difficult to use.
Therefore, it is often preferable to perform a switched array sector scan using a convex type probe so that a large screen can be scanned at the back. In the scanning method in which scanning is performed by irradiating from the element at one end (referred to as the left end) of the ultrasonic probe, and sequentially moving from the center to the other end (referred to as the right end), scanning is performed from the left end element. Shifting the sound ray to the left when it is on, shifting the sound ray to the front for the center element, and moving the sound ray to the right for the rightmost element, etc. In some cases, a sliding aperture faced array system that simultaneously shifts the azimuth of a line is employed.

However, when trying to cover multi-purpose with only one probe, the sound field scanning range is narrower (in case of magnification of 1.4 in Fig. 6).
The roughness of the sound ray is conspicuous, and a good image cannot be obtained.

The present invention has been made in view of the above points, and an object of the present invention is to provide an ultrasonic diagnostic apparatus that displays a favorable ultrasonic image in a fixed size on a screen even when a display magnification is smaller than 1. Is to do.

(Means for Solving the Problems) The present invention for solving the above problems incorporates software for controlling a required circuit by selecting a method of scanning a sound field by an ultrasonic probe according to the type of display magnification. A transmission timing pulse generating circuit that generates a transmission timing pulse having a pulse repetition frequency corresponding to a depth of a sound field that differs depending on a display magnification under the control of the controller, and an input pulse signal that is controlled by the controller. A transmission beamformer that converts a multi-bit signal having information such as the ignition timing of each element of the ultrasonic probe or the delay amount of a signal input to each element according to the type of display magnification, and the controller A receiving beamformer for phasing and adding the received signal in accordance with the forming form of the transmitting beamformer; An echo filter for filtering an input signal with a frequency characteristic corresponding to the depth of the subject region that varies depending on the type of display magnification under the control of the controller is provided.

(Operation) The transmission timing pulse of the repetition frequency corresponding to the depth of the sound field according to the set display magnification generated by the transmission timing pulse generator is a signal that forms a sound field adapted to the display magnification in the transmission beamformer. And emitted from the ultrasonic probe. The echo signal is tuned and added in the receiving beamformer so as to conform to the display magnification, and is filtered by an echo filter adjusted to a frequency band corresponding to the depth of the sound field.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. In the figure, the internal structure of the ultrasonic probe 1 is schematically shown. Reference numeral 11 denotes a high-voltage multiplexer that is provided inside the ultrasonic probe 1 and that sequentially distributes high-voltage transmission signals of 32 channels to the element array 12 of 256 channels. Reference numeral 13 denotes a transmission timing pulse generation circuit that generates a timing pulse for transmitting an ultrasonic pulse, and 14 converts an input pulse into a 32-bit signal and ignites each element of the ultrasonic probe 1. This is a transmission beamformer for forming a sound ray by controlling the timing.
Reference numeral 15 denotes a transmission amplifier that power-amplifies the output signal of the transmission beamformer 13, a TR switch that prevents the transmission signal from being sent to the reception circuit and prevents the reception signal from going to the transmission circuit,
This is a TR circuit group including a preamplifier for amplifying a received signal.

Numeral 16 denotes a receiving beamformer for phasing and adding the received signal output from the TR circuit group 15 to convert it into a time-series serial signal. The output is amplified by an amplifier 17 and input to a logarithmic compression circuit 19. Reference numeral 20 denotes a detector that detects the output of the logarithmic compression circuit 19 and sends out a video signal to a subsequent circuit. 21 includes control software therein, and controls the operation of the transmission timing pulse generation circuit 13, the transmission beam former 14, the reception beam former 16, and the echo filter 18 according to instructions of the control software. A controller that inputs a control signal to each of the circuits. The controller 21 has an element array for the transmit beamformer 14 and the receive beamformer 16
It is possible to freely control which of the twelve elements is adopted, and how much delay is applied to the adopted element to contribute. Here, it is assumed that the quantization error of the set delay amount is sufficiently small.

Next, the operation of the embodiment configured as described above will be described. When using the ultrasonic diagnostic apparatus, the operator first sets various operating conditions including setting of the display magnification to the controller 21 via an input device (not shown). The operator gives a scan start command after setting through the input device. The transmission timing pulse generation circuit 13 generates a transmission pulse,
The transmission pulse is transmitted to the transmission beam former 14. The pulse generated by the transmission timing pulse generation circuit 13 has a pulse repetition frequency changed according to the depth of the sound field under the control of the controller 21. The transmission beam former 14 is controlled by the controller 21 as follows. That is, when the display magnification is 1 time of FOV, there is no difference from the normal scanning. For example, scanning is performed by a switching method as usual so as to use all 256 elements of the linear array of 256 elements, and the transmission beamformer is used. Numeral 14 performs only electronic focus within the aperture adopted each time switching is performed. When the display magnification is 0.7 ×, 0.5 × and the magnification is small, that is, when scanning the space to be inspected more widely, the beam operation direction (azimuth) of the sound ray in the sound field is adjusted in step with the above switch operation. Is provided with a delay distribution so that the beam is obliquely irradiated within the aperture adopted each time switching is performed by the switch so that the offset sector scan as shown in FIG. 2 is performed. In other words, there is no delay distribution for that in front of the center, and only electronic focus is performed,
In addition to the electron focus, the first-order delay distribution is superimposed and executed so that the beam enters and exits outward as approaching both ends of the element array 12. On the other hand, when the display magnification is increased to 1.4 times or 2 times, the elements in the aperture are weighted or the delay distribution for electronic focusing is moved so that the sound ray moves at a finer pitch than the movement of the adopted aperture by the switch operation. The linear scan is performed while controlling the virtual position of the sound ray by performing vernier control or the like. When this is put together, it becomes as shown in FIG.

The signal processed by the transmission beam former 14 as described above is subjected to processing such as power amplification in the TR circuit group 15 and then input to the high voltage multiplexer 11 as a 32-bit signal. The high-voltage multiplexer 11 excites the element array 12 and emits ultrasonic waves while sequentially allocating the elements to 256 channels according to the difference in the display magnification of the 32-bit signal.

The transmitted ultrasonic wave returns from the reflector as an echo, is converted into an electric signal by the element array 12,
32 bit signal in the high voltage multiplexer 11
The signal is input to the receiving beamformer 16 via the TR circuit group 15.
The receiving beamformer 16 is subjected to the same control as that for the transmitting beamformer 14 by the controller 21, performs phasing addition of the input signal, and outputs a pulse representing the state of the echo. The output signal is amplified by the amplifier 17 and filtered by the echo filter 18. The echo filter 18 is also controlled by the controller 21 to change its filtering frequency band in accordance with the echo return time and output an optimal signal. The output signal is logarithmically compressed in a logarithmic compression circuit 19,
It is detected by the detector 20 and sent to the subsequent circuit, where it is displayed on a display circuit (not shown). On this display screen, an echo of the entire sound field is displayed on the entire screen regardless of the display magnification. This display screen 2 is shown in FIG. In the figure, when the display magnification is 2 times, 1.4 times, and 1 time, the screen is completely displayed as shown by a solid line, and when the display magnification is 0.7 times and 0.5 times, the screen is almost completely displayed as shown by a broken line. You.

As described above, according to the present embodiment, the controller 21
In this case, it is possible to display the same conditions on the entire screen with respect to transmission of different display magnifications using one linear array probe.

The present invention is not limited to the above embodiment.
In the embodiment, the method in which the beam former is operated by the electronic control method has been described. However, the method may also be used in a method employing a pantograph mechanism in which one vibrator is mechanically horizontally moved or moved like a convex scan or sector scan. Of course. This method can be realized if there is a function of moving the vibrator while rotating it in the liquid chamber. FIG. 5 shows scanning by this method. In the figure,
(A) is a scan with a display magnification of 1.4 times, and the vibrator 22 is moved in equilibrium within the range shown in the figure. (B) is a case where the display magnification is 1 times and the vibrator 22 is ultrasonically moved. The figure in which the probe 1 is moved over the entire width, and the figure (c) shows that the display magnification is 0.7
In the figure for double, the transducer is like a convex scan
FIG. 22D shows the vibrator 22 being swung like sector scan at the same magnification. Vibrator driving means (not shown) for moving the vibrator 22 in this manner
Is controlled by the controller 21, the same effect as in the above embodiment can be obtained.

In addition, a method of oscillating the transducer 22 by moving a quadrilateral drawn between two points in the ultrasonic probe may be considered.

(Effects of the Invention) As described in detail above, according to the present invention, a good ultrasonic image can be displayed on a screen at a constant size even when the display magnification is set to be smaller than 1.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus according to one embodiment of the present invention, FIG. 2 is a diagram of a sound field formed by this embodiment, FIG. 3 is a diagram showing a scanning format at each display magnification, and FIG. FIG. 5 is a diagram of image display according to the present embodiment, FIG. 5 is a diagram of scanning according to another embodiment of the present invention, and FIG. 6 is a diagram of a shape of a sound field by a conventional ultrasonic device and an image on a display screen. DESCRIPTION OF SYMBOLS 1 ... Ultrasonic probe, 11 ... High voltage multiplexer 12 ... Element array 13 ... Transmission timing pulse generation circuit 14 ... Transmission beamformer 15 ... TR circuit group, 16 ... Reception beamformer 18 …… Echo filter 19 …… Logarithmic compression circuit, 20 …… Detector 21 …… Controller

Claims (1)

(57) [Claims] 1. A display magnification for displaying a region of an object scanned by using an ultrasonic probe at a fixed size as an ultrasonic image on a screen is changed, and the display magnification is changed. An ultrasonic diagnostic apparatus that generates the ultrasonic image by changing the scan in response to an ultrasonic wave generated by the ultrasonic probe on a surface including a scanner surface when the display magnification is smaller than 1. Means for performing a scan for forming an ultrasonic beam from an area outside a line vertically lowered from the end of the receiving part toward the subject toward the end of the ultrasonic receiving part. Ultrasound diagnostic device.