JPH04152939A - Ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To variably set the scanning density in a state that a prescribed number of scanning lines of a focusing ultrasonic beam to be transmitted/ received is maintained as it is by giving a prescribed delay time to each of plural vibrators and transmitting or receiving it. CONSTITUTION:When an operator desired to observe the image of a higher bearing resolution by the tomographic image of a display screen, the operator sets a scanning density variable setting switch on an operating panel 11 to a desired position. Thus, a CPU 8 outputs delay data for narrowing a scanning angle between the initial direction and the final direction to the transmitting/ receiving surface of an ultrasonic beam for executing a scan by standard scanning density, and also, while keeping the number of beams in its scanning angle and the depth of focus constant, and reducing the deflection angle of every transmission/reception, to a first and a second phasing circuits 3, 4 for transmission, and a first and a second phasing circuits 5, 6 for reception. In such a manner, the image of a desired bearing resolution is obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is used in the field of ultrasonic diagnostic equipment, and particularly relates to a technique for variably setting the ultrasound examination area in sector scanning or convex scanning equipment. It is.

[Conventional technology]

There are currently three methods for scanning ultrasound beams in ultrasound diagnostic equipment: linear scanning, which scans the beam in parallel; sector scanning, and convex (also called curved linear) scanning, which scans the beam radially. is the mainstream.

Images from an ultrasonic diagnostic apparatus are real-time images of about 30 frames/second, but the resolution of the images must be understood in terms of both spatial and temporal resolution. The speed at which ultrasound waves propagate through living organisms such as the human body is approximately 1,500 m/s, and the frame rate that makes flickering of images less noticeable on the TV monitor screen that displays ultrasound images is approximately 30 m/s.
There is a frame/second constraint. Taking these two constraints into consideration, the number of ultrasound beam scanning lines and their density for one image are set in the ultrasound diagnostic equipment so as to optimize the two resolutions and the scanning range that can be inspected in one scan. has been done.

In other words, in the conventional apparatus, the range that can be inspected by one scan of the ultrasonic beam, the number of scanning lines therefor, and therefore the scanning line density are also set to predetermined values unique to the apparatus.

However, in recent years, research and development of electronic sector type devices that test circulatory organs such as the heart has progressed, and the function of displaying the heart and blood flow using the Doppler effect is an essential requirement for this type of electronic sector type device. be.

However, in order to utilize the Doppler effect, it is necessary to transmit and receive ultrasound beams multiple times in one direction. However, when using this method, the frame rate of ultrasound images is lower than that of normal B mode due to the above constraints. It is inevitable that it will decline significantly. Therefore, in the blood flow display mode, the number of scanning lines is decreased without changing the scanning line density, that is, the inspection area is narrowed, and the frame rate is kept as high as possible. That is, in such a device, the maximum scanning range in normal B mode scanning is set to be scanned at a predetermined scanning line density, and in blood flow display mode, the scanning line density is maintained or the scanning lines are thinned out. , and narrowing the scanning range is common practice.

[Problem to be solved by the invention]

In the conventional device described above, when considering B-mode display, the scanning range and scanning line density are fixed, so even if the resolution (especially azimuth resolution) is lowered, you may want to inspect a wide area on one screen, or Since the range can be narrowed, it has been impossible to meet the demand for inspection using images with high lateral resolution.

Therefore, an object of the present invention is to provide an ultrasonic diagnostic apparatus that can meet the above-mentioned demands.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an ultrasonic probe having a plurality of transducers arranged, and a focused ultrasonic beam that is sequentially transmitted radially by a predetermined number of scanning lines at a predetermined scanning line density. In an ultrasonic diagnostic apparatus, the ultrasonic diagnostic apparatus includes a transmitting/receiving means including a first transmitting/receiving wave phasing means for transmitting and receiving, and a display means for displaying an echo signal taken in by the probe and the transmitting/receiving means. A second wave transmitting/receiving phasing means is provided which can variably set the scanning g density while maintaining a predetermined number of scanning lines of the ultrasonic beam.

[Effect]

In order to converge the ultrasonic beam or change the directivity, it is only necessary to transmit or receive by giving a predetermined delay time to each of the plurality of transducers.In the above configuration, only the first wave transmitting/receiving phasing means is used. When operated, the field of view (inspection area) is set at the standard scanning line density for the device. If you want to obtain an image with good resolution even if the field of view is narrower than that,
If you want to widen the viewing range even if the resolution is poor, you can switch the second wave transmitting/receiving phasing means from the first wave transmitting/receiving phasing means, or switch the second wave transmitting/receiving phasing means to the first wave transmitting/receiving phasing means. It is operated by adding a transmitting/receiving wave phasing means. This allows the scanning liA density to be variably set without changing the number of scanning lines.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows the concept of the present invention; FIG. 1 shows an example of the electronic sector system, and FIG. 2 shows an example of the convex system. In the electronic sector method, as shown in FIG. 1, a probe 10 is provided with n vibrators #1 to #D in an array. When each of these transducers #1 to #n transmits and receives a delay time using a transmitting/receiving phasing circuit described later, the ultrasonic beam is deflected in a predetermined direction and focused at a predetermined depth. is formed. The delay time given to each transducer is specified by the deflection angle of the ultrasound beam and the depth of the focal point P (depth of focus), and the total scanning angle, number of scanning lines N, and depth of focus F are set. Then, the fourth
As shown in the figure, the delay time τ given to the transducer i to generate the scanning line number n (the deflection angle at this time is θ)
, is determined by equation (1).

...(1) 22 i: Transducer number d: Transducer arrangement pitch C: Ultrasonic velocity in the living body (i - 1) d-sin θ/C in equation (1) is for deflection. The delay time and (i-1) are also d, /8CF・
cos θ represents the delay time for focusing.

When the set of long continuous time determined in this manner is sequentially given to each transducer #1 to #n in the order of scanning line number by the first transmission/reception wave phasing means and scanned from NQ1 to &N, the result is shown in Fig. 1(a). As shown in Figure 2, an ultrasound image with standard scanning line density is obtained.

On the other hand, in FIGS. 1(b) and 1(c), the scanning line density is changed. In each of these cases, the delay time given to each vibrator can be determined by calculating θ in the above equation (1) for each scanning line number.

These delay times are given to each vibrator by the second transmission/reception phasing means, but the following may be considered as a special case. That is, for the standard scanning line density shown in FIG. 1(a), the scanning in the case of FIG. 1(b) or (c)! ! When the density is double or triple, the positions of the scanning lines may overlap. Therefore, for scanning lines to be superimposed, the first transmission/reception wave phasing means is used, and for other scanning lines, the second wave phasing means is used.
The delay time may be provided by the transmitting/receiving wave phasing means.

Next, the convex scanning method will be explained with reference to FIG. As mentioned above, convex scanning is also called curved linear scanning, and is a type of linear scanning.The probe used for it has multiple transducers arranged in an arc, and each emitted ultrasonic wave The beam is oriented normal to the arc (see FIG. 2(a)). In other words, delay control for deflection is not performed, but only delay control for focusing is performed. Therefore, the transmitting/receiving phasing means (first transmitting/receiving phasing means) in the convex scanning method only needs to have enough components to give a predetermined delay time to the number of oscillators arranged during one transmission/reception. It was something.

The present invention also provides a second wave transmitting/receiving phasing means in the convex method as well as in the sector method, as shown in FIG. 2(b) or (c).
It deflects the ultrasonic beam as shown in the figure. The delay time given to each transducer in order to deflect and focus the ultrasonic beam can be calculated or geometrically obtained in the same manner as the sector method described above, but its explanation will be omitted here.

Next, an embodiment embodying the present invention will be described with reference to FIG. In Fig. 3, 1 is an electronic sector type ultrasonic probe or a convex type ultrasonic probe, 2 is a transmitting/receiving circuit, which is a balsa for transmitting waves that supplies active pulses to a group of transducers, a switching circuit, and a wave receiving circuit. This includes amplifiers, switching circuits, etc. 3 is a first phasing circuit for wave transmission, 4 is a second phasing circuit for wave transmission, 5 is a first phasing circuit for delivery, and 6 is a second phasing circuit for wave reception. 7 has a memory for storing the output signal of the wave receiving phasing circuit, and controls ultrasonic scanning at T.
A digital scan converter (hereinafter referred to as +DSC) that performs V-display scan conversion, 8 a CPU that controls each part of the device, 9 a signal input to the CPU, and a CPU 8
■/○ port for signal output from to each part, 10 is C
A display device such as a TV monitor equipped with an RT, and 11 an operation panel on which various switches including a scanning line density variable setting switch are arranged.

Next, the operation of the apparatus configured as described above will be explained. The operator operates the scanning line density variable setting switch (this corresponds to the switch that sets the scanning angle of the ultrasonic beam emitted from the probe, since the number of scanning lines is constant). The scanning line density is set depending on the size of the examination area, whether the detailed examination is screening, etc. Assume now that a standard scanning line density has been set. Next, the probe 1 is brought into contact with the subject 20 and an operation is performed to start ultrasonic scanning. Then, C
The PU 8 outputs delay data given to each transducer in order to set the ultrasound transmission direction and focal depth, and the first phasing circuit 3 for transmission and the first phasing circuit 5 for reception are controlled. .

The delay data is updated and output every time ultrasound is transmitted and received;
As a result, the ultrasound beam is sequentially deflected at a deflection angle that provides a standard scanning line density for each transmission and reception. And probe 1.
The echo signal taken in via the transmitting/receiving circuit 2 and the first wave transmitting phasing circuit 5 is digitized into the memory of the DSC 7, written in synchronization with the timing of transmission and reception, and read out with the timing of the horizontal synchronization signal of the TV monitor. and displayed on the TV monitor 10 as a tomographic image.

When the operator wishes to observe an image with higher lateral resolution from the tomographic image on the display screen, the operator adjusts the scanning line density variable setting switch on the operation panel 11 to a desired position. Then: The CPU 8 narrows the scanning angle between the initial direction and the final direction of the ultrasonic beam scanning at the standard scanning line density with respect to the transmitting/receiving surface, and keeps the number of beams and the depth of focus within the scanning angle constant. , delay data for reducing the deflection angle for each transmission/reception are sent to the transmitting box 1°, the second phasing circuits 3 and 4, and the receiving box 1°. It is output to the second phasing circuits 5 and 6. Although a detailed explanation will be omitted, it will be easily understood that an image with a desired lateral resolution can be obtained by this.

Although this embodiment has been described using an example in which two phasing circuits are provided for transmitting and receiving waves, the present invention is not limited to this, and a single phasing circuit for each is used as described above. It goes without saying that the configuration may be such that the ultrasonic beam can be deflected in various ways.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to variably set the density of ultrasound scanning lines while maintaining the number of ultrasound scanning lines constituting one ultrasound tomographic image at a predetermined value. If you want to observe a narrow area with high lateral resolution, as in I can handle it. This results in
It becomes possible to perform ultrasonic diagnosis efficiently and with high precision.

[Brief explanation of drawings]

Fig. 1 shows the scanning situation of three ultrasonic beams when the present invention is applied to an electronic sector scanning method, and Fig. 2 shows the scanning situation of three ultrasonic beams when the present invention is applied to a convex scanning method. FIG. 3 is a block diagram showing the configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention, and FIG. 4 is an explanatory diagram of focusing and deflection of ultrasonic waves in the electronic sector system. 1. Probe, 2. Transmission/reception circuit, 3. First phasing circuit for transmitting waves, 4. Second phasing circuit for transmitting waves, 5. First phasing circuit for receiving waves, 6 ...Second phasing circuit for wave reception, 7...DSC1st

Claims (1)

[Claims] 1. An ultrasonic probe formed by arranging a plurality of transducers, and a first transmission/reception wave phasing device that sequentially transmits and receives a focused ultrasonic beam radially at a predetermined number of scanning lines at a predetermined scanning line density. In an ultrasonic diagnostic apparatus, the ultrasonic diagnostic apparatus includes an ultrasonic transmitting/receiving means including a means for transmitting and receiving an ultrasonic wave, and a display means for displaying an echo signal captured by the probe and the transmitting/receiving means. An ultrasonic diagnostic apparatus comprising a second wave transmission/reception phasing means that can variably set the scanning line density while maintaining the number of scanning lines.