JP5416947B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus having a Doppler mode for providing blood flow velocity information.

  The ultrasonic diagnostic device applies delay control according to the focus position to each channel corresponding to the probe element, obtains an echo signal in focus by performing transmission and reception beam forming, and based on it I'm building an image.

  The accuracy of beam forming is related to the so-called beam width, and it is required that the ratio of the sensitivity to the focus position and the sensitivity to signals from other locations is large. Since it is desirable to visualize the signal reflected from the focus position, it is a general idea that the beam width is desirably “narrow” or “narrow”.

  One of the effects expected when the system evolved from analog to digital was the improvement in beam forming accuracy. In other words, until now, analog delay lines have been used as reception delay circuits, for example, but this resolution is not necessarily small enough and there are variations between parts, so the accuracy of reception beam forming is also required. I didn't stay in value. On the other hand, since digital is processed at a constant clock rate, if the rate is sufficiently small, an improvement in accuracy can be expected, and variations between devices can be ignored.

In an apparatus that digitally processes a signal, the beam width can be narrowed as long as the clock rate can be reduced, or within an error range (for example, quantization error of control data) depending on the processing method (see Patent Document 1).
JP 2006-87677 A

  However, in the Doppler mode in which the blood flow velocity is detected with a fixed focus, the thinner the beam width, the better.

  For example, when trying to detect a pathological high-speed flow that occurs locally, if the beam is too thin, the blood flow will be lost if the setting focus (in this case, set by the user from the device control panel, etc.) removes the local area even slightly. There is a possibility of falling into the situation of missing. Normally, the user knows where the high-speed flow is generated in the color mode and moves to the CW Doppler mode to read the speed from the detected waveform in order to quantitatively grasp the speed. Here, the focus is set with a trackball or the like using the “color” of the color mode image as a guide, but if the volume of the pathological high-speed flow generation point is small and the beam is thin, a more accurate focus setting operation is required. . FIG. 1 is a schematic diagram showing the positional relationship between an ultrasonic beam and blood flow for explaining the problem of the present invention. FIGS. 1A and 1B show the shape of the beam 12 emitted from the ultrasonic transducer 11, respectively. The former beam width is wider than that of the latter. Each beam 12 is adjusted to a pathological high-speed flow generation point 13 to be measured at a focal position where the beam width is the smallest. However, as shown in FIG. 1B, when the beam width at the focal position becomes narrow and the beam deviates from the pathological high-speed flow generation site 13, the intensity of the echo signal reflected from the Doppler shift is increased. Weaken. In some cases, it is buried in noise, and the originally expected speed component cannot be detected.

  Accordingly, an object of the present invention is to provide an ultrasonic diagnostic apparatus capable of changing the beam width in accordance with a target location to be diagnosed.

The ultrasonic diagnostic apparatus of the present invention includes a plurality of ultrasonic transducers arranged to transmit or receive ultrasonic signals, and a drive pulse signal to these ultrasonic transducers via a plurality of transmission / reception changeover switches. A transmission beam forming control circuit for controlling a delay amount of the drive pulse supplied to the transmission circuit , and the ultrasonic signal received by each ultrasonic transducer is connected to the transmission / reception changeover switch . And a receiving beamforming control circuit to which the output signals of these receiving circuits are supplied, respectively, and an ultramode equipped with a diagnostic mode for detecting blood flow velocity at a fixed focus. An ultrasound diagnostic apparatus,
The reception beam forming control circuit further includes a quantization precision selection signal input device, and the delay quantization amount determining apparatus for determining a delay quantization weight based on the supplied quantization precision selection signal by the input device, the based on the determined delay quantized amount of delay quantization amount determining device, a signal delay imparting a quantization circuit which performs quantization to the delay amount, a delay amount in which the quantized output signal of the previous SL respective receiving circuits And a signal synthesizer for synthesizing the output signals of the reception signals delayed by the signal delay circuit.

  In the ultrasonic diagnostic apparatus of the present invention, the accuracy information output of the delay quantization amount determination device is also supplied to the transmission beamforming control circuit, and the accuracy of transmission and reception beamforming can be controlled independently. It is characterized by.

  Furthermore, in the ultrasonic diagnostic apparatus of the present invention, the accuracy of the transmission and reception beam forming is selected by the quantization accuracy selection signal input device.

  As described above, in the ultrasonic diagnostic apparatus according to the embodiment of the present invention, assuming that the beam forming accuracy required in other modes can be ensured, in the digital system, the beam width is increased from there. Alternatively, it is relatively easy to change the beam forming accuracy. That is, in the process of calculating the delay control parameter, it is possible to determine a certain quantization range and output the parameter with the accuracy.

  ADVANTAGE OF THE INVENTION According to this invention, when a user controls the beam width of an ultrasonic wave according to a use purpose, it can contribute to a highly accurate diagnosis.

  2 to 4 are diagrams for explaining the principle of the present invention. FIG. 2 is a block diagram showing an example of a receiving circuit configuration of an ultrasonic diagnostic apparatus to which the present invention is applied. N ultrasonic transducers 11-1, 11-2, 11-3,..., 11 -N that transmit or receive ultrasonic signals of N channels (0, 1, 2, 3,..., N−1). Are supplied with drive pulse signals from the transmission circuit 15 via transmission / reception changeover switches (T / R switches) 14-1, 14-2, 14-3,..., 14-N, respectively. The ultrasonic pulse signals emitted from the N ultrasonic transducers 11-1, 11-2, 11-3,..., 11 -N and reflected from the object are again N ultrasonic transducers 11-. 1, 11-2, 11-3,..., 11-N are received and converted into electrical signals. These received signals are amplified by receiving circuits 16-1, 16-2, 16-3,..., 16-N via T / R switches 14-1, 14-2, 14-3,. .., 17-N, respectively, are converted into digital signals by AD converters 17-1, 17-2, 17-3,. The received signals of each channel converted into digital signals are sequentially stored in first-in / first-out memories (FIFO memories) 18-1, 18-2, 18-3,.

  The received signals of each channel stored as digital information in the FIFO memories 18-1, 18-2, 18-3,..., 18 -N are received by the write / read control signal from the write / read control circuit 19. .., 18-N are read out at a timing determined in accordance with the delay amount to be handled by the adder circuit 20. Is added.

  These FIFO memories 18-1, 18-2, 18-3,..., 18-N, the write / read control circuit 19 and the adder circuit 20 perform so-called reception beam forming processing.

Here, the read control by the FIFO memories 18-1, 18-2, 18-3,..., 18-N corresponds to the reception delay process, specifically, the read address is calculated and supplied to each memory. Become. For a mode that applies dynamic reception focus that updates the focus from time to time, such as the B mode, the address is obtained from a delay amount dn (t) expressed by the following equation.

FIG. 3 is a diagram for explaining how to obtain the delay amount dn (t) represented by the above equation (1).
In the figure, an XY coordinate represents a two-dimensional plane to be scanned by an ultrasonic beam, and a plurality of ultrasonic transducers 11 forming an ultrasonic flow part are placed on the Y axis with focus start coordinates (initial focus). (Position) (xini, yini). One coordinate of any of these ultrasonic transducers 11 is (xn, yn), and the focus coordinate at a certain time t is (x _f , y _f ). Here, v is the speed of sound, and θ is the angle between the X axis and the traveling direction of the ultrasonic beam, that is, the scan angle at time t.

ここで、Tがクロックレートで、[ ] は整数化処理を表わす。 An address is obtained by dividing the delay amount dn (t) obtained in this way by the system clock rate.

Here, T is a clock rate, and [] represents an integer processing.

整数化処理について第1項と2項を分けると、

The above is an example when dynamic focus is applied. In the fixed focus mode such as CW Doppler to which the present invention is applied, the delay amount dn (t) and the address are given by the following equations (3) and (4). That is, in this case, the focus (x _f , y _f ) that is updated every moment does not exist, and the fixed focus position is represented by the initial focus position (x _ini , y _ini ).

Dividing the first and second terms into integer processing,

で、焦点位置から決まる各チャンネルに固有の定数である。 The second term is the time divided by the clock rate, that is, the quantization time, and therefore corresponds to a monotonic increase of the address 'k'. Including this, the above equation is rewritten as follows.

Thus, it is a constant specific to each channel determined from the focal position.

The above formula shows the following. That is, the read address at the fixed focus is monotonously increased with an offset [D _n / T] unique to the channel.

Here, it is the accuracy of [D _n / T] that determines the beam width. Conventionally, quantization is performed at the system clock rate 'T', and in this case, beam forming is performed with the highest accuracy of the system. Another good thing is to reduce the beam width to the minimum. Here, as described above, it is not always possible that the beam width is narrow. Especially when a minute blood flow is detected, a beam width that is too narrow may make it difficult to make them difficult.

Therefore, in the present invention, as described above, the quantization accuracy is made variable. When discussing the accuracy of beamforming, it is based on the wavelength of the transmission / reception center frequency. For example, assuming the quantization accuracy of 1/32, 1/16, 1/8, and 1/4 of the wavelength, switching is performed. To be able to. Taking the transmission / reception center frequency of 2 MHz as an example, since the period corresponding to one wavelength is 500 ns, the above quantization accuracy is 15.625 ns, 31.25 ns, 62.5 ns, and 125 ns. This is applied as “T _Q” instead of the above formula “T”.

FIG. 4A is a block diagram showing “T _Q ” input to the beamforming control circuit and its determination process. In the figure, a quantization accuracy selection signal input device 41 is a device that selects which level of quantization accuracy to select, and is selected by the user. Information representing the quantization accuracy value selected by the input device 41 is determined by the delay quantization amount determination device 42 by the quantization accuracy TQ in the above equation (8), and the transmission beamforming control circuit 43 or the reception beamforming. It is supplied to the control circuit 44. Based on the quantization accuracy TQ determined by the delay quantization amount determination device 42, the transmission beamforming control circuit 43 or the reception beamforming control circuit 44 outputs the address _An [k] by the above equation (8). It will be.

  FIG. 4B is a block diagram illustrating a more specific configuration example of the delay quantization amount determination device 42. This device 42 selects any one of, for example, four types of quantization parameters TQ0, TQ1, TQ2, and TQ3 by a selection signal from the quantization accuracy selection signal input device 41 and outputs it as an output signal TQ.

  FIG. 5 is a block diagram of an ultrasonic diagnostic apparatus showing an embodiment of the present invention. In this figure, the same or corresponding components as those of the ultrasonic diagnostic apparatus shown in FIGS. 2 to 4 are designated by the same reference numerals, and detailed description thereof will be omitted unless particularly necessary.

  The input device 41 and the delay quantization amount determination device 42 in the figure correspond to each device described in FIG. Here, the transmission pulse generation circuit 51 corresponds to the transmission beamforming control circuit 43 in FIG. 4 and is supplied with the quantization accuracy TQ determined by the delay quantization amount determination device 42 as an input signal, and the delay amount determined thereby. Is generated and supplied to the transmission circuit 15. The transmission circuit 15 receives a transmission timing signal output from the transmission pulse generation circuit 51, and generates a high-voltage pulse for driving the ultrasonic transducers 11-1, 11-2, 11-3, ..., 11-N. It is. The T / R switches 14-1, 14-2, 14-3,..., 14-N protect the receiving circuit from being broken at a high voltage while transmitting a high voltage pulse to the vibrator at the time of transmission. The echo signal from the transducer is transmitted to the subsequent stage. The receiving circuit 53 corresponds to the receiving circuits 16-1, 16-2, 16-3,..., 16-N and AD converters 17-1, 17-2, 17-3,. Then, a weak echo signal is amplified so that it can be processed later. In digital systems, AD converters are included here. The receive beamformer 54 is connected to the receive beamforming control circuit 44 in FIG. 4 and the FIFO memories 18-1, 18-2, 18-3,..., 18-N, the write / read control circuit 19 and the adder circuit 20 in FIG. Correspondingly, each channel echo signal is added with an appropriate delay. The FIFO read address generation circuit 52 corresponds to the write / read control circuit 19 in FIG.

  According to the embodiment of the present invention, it is possible to control the beam width by determining the delay quantization amount by the delay quantization determination process according to the user's instruction and outputting the information to the beamforming control circuit. The beam can be formed adaptively depending on the diagnosis situation.

  FIG. 6 is a block diagram of an ultrasonic diagnostic apparatus showing another embodiment of the present invention. In this figure, components that are the same as or equivalent to the components of the ultrasonic diagnostic apparatus shown in FIG. 5 are given the same reference numerals, and detailed descriptions thereof are omitted unless particularly necessary.

  In the embodiment of FIG. 5, the same delay quantization amount is applied to transmission and reception beamforming. However, in this embodiment, for example, “transmission is thick and reception is thin” or vice versa, It is an object of the present invention to provide an ultrasonic diagnostic apparatus capable of freely selecting the thickness of a transmission beam and a reception beam.

In this device, the input device 41 and the delay quantization amount determination device 42 set the transmission beamforming quantization accuracy to “T _QT ” and the reception beamforming quantization accuracy different from “T _QT ”. “T _QR ” is output and supplied to the transmission pulse generation circuit 51 and the FIFO read address generation circuit 52, respectively. That is, different quantization precisions “T _QT ” can be applied to transmission beam forming and “T _QR ” can be applied to reception beam forming.

  Since other components of the present embodiment are the same as those of FIG. 5, detailed description thereof will be omitted.

  FIG. 7 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus showing still another embodiment of the present invention. In the examples so far, the reception beamformer has been described as a FIFO memory and an adder. However, in the present embodiment, a reception beamformer having a different form is used. That is, the reception beamformer of this embodiment first applies direct detection to the reception signal which is an input signal using the first mixers 71-1 and 71-2, and the baseband signal of the in-phase component I and the quadrature component Q Are obtained through band-pass filters 72-1 and 72-2, respectively. In the figure, multiplication by cos (ωc · Dn) and −sin (ωc · Dn) represents quadrature detection. Next, the baseband signals of the in-phase component I and the quadrature component Q are digitally converted by the AD converters 73-1 and 73-2. Then, using the second mixers 74-1 and 74-2, the I / Q signals multiplied by the coefficients are added to each other by the addition operation using the first adders 75-1 and 75-2. Control and give the required delay to that channel. The channel I / Q signals whose phases are aligned in this way are added together by the second adders 76-1 and 76-2, and reception beam forming is completed.

Here, the accuracy of beam forming is determined by the coefficient coef _A / coef _B. These delay coefficients can be generally expressed as follows.

Here, ω _c is the center frequency of the echo signal, and D _n is the delay time specific to that channel, which can be expressed by equation (7). When the coefficient obtained by the above equation is applied, the reception delay determined by the relationship between each element and the focus setting position is accurately applied. In other words, the receive beam is the thinnest.

Here, in order to control the beam width in accordance with the gist of the present invention, the delay coefficient is calculated as follows using the above-described quantization parameter “T _QR ”.

  Here, [] is an integerization process as described above. Since the delay time is quantized, the phase of the I / Q signal to be controlled as a result also changes stepwise with a certain change width. The formed receive beam is no longer accurate and has a certain displacement therefrom. That is, the beam width is increased.

  FIG. 8 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus showing still another embodiment of the present invention. In this embodiment, a reception beamformer using an I / Q signal (referred to as an I / Q reception beamformer) as shown in FIG. 7 is applied. In this figure, components that are the same as or equivalent to the components of the ultrasonic diagnostic apparatus shown in FIG. 5 are given the same reference numerals, and detailed descriptions thereof are omitted unless particularly necessary.

In this embodiment, a delay coefficient calculation device 81 is used instead of the FIFO read address generation circuit 52 of FIG. 5, and an I / Q reception beamformer 82 is used instead of the reception beamforming control circuit 54 of FIG. The I / Q reception beamformer 82 is a circuit that performs an operation as shown in FIG. 7, receives the quantization accuracy parameter “T _QR ”, and outputs a delay coefficient as shown in the above equations (11) and (12). .

According to the embodiment of the present invention described above, the user can control the beam width of the ultrasonic wave, which has been conventionally determined uniformly, according to the purpose of use. This is particularly effective when a minute blood flow is detected, and it may be difficult to detect them with a narrowly focused beam. For example, at the start of scanning, a relatively thick beam is formed in order to first confirm the presence or absence of blood flow. Therefore, in the examples so far, for example, the delay is quantized with a quantization accuracy of 1/8 of the wavelength of the frequency used. As a result, the sensitivity over a wider range can be set, so that it is possible to reduce the situation such as “the blood flow thought to have been seen in the color mode cannot be taken”. After confirming the presence or absence of blood flow, it is necessary to specify the position more accurately and determine the speed. Therefore, it is possible to narrow down the beam width and perform finer scanning with the highest accuracy of the system.
In this way, the ability to detect micro blood flow can be particularly improved, and it can contribute to highly accurate diagnosis.

  As mentioned above, although this invention was demonstrated in detail by some embodiment, this invention is not limited to these embodiment, A various deformation | transformation is possible within the range of the technical idea of this invention.

It is a schematic diagram which shows the positional relationship of the ultrasonic beam and blood flow for demonstrating the subject of this invention. It is a block diagram which shows one example of the receiving circuit structure of the ultrasonic diagnosing device to which this invention is applied. FIG. 3 is a diagram for explaining how to obtain the delay amount dn (t). FIG. 4A is a block diagram showing “T _Q ” input to the beamforming control circuit and its determination process, and FIG. 4B is a block showing a more specific configuration example of the delay quantization amount determination device. FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus showing an embodiment of the present invention. It is a block diagram of the ultrasound diagnosing device which shows other embodiment of this invention. It is a block diagram which shows the structure of the ultrasonic diagnosing device which shows other embodiment of this invention. It is a block diagram which shows the structure of the ultrasonic diagnosing device which shows other embodiment of this invention.

Explanation of symbols

11-1, 11-2, 11-3, ..., 11-N1 ultrasonic transducer 12 beam 13 blood flow 14-1, 14-2, 14-3, ..., 14-N T / R switch 15 transmission circuit 16-1, 16-2, 16-3, ..., 16-N receiving circuit 17-1, 17-2, 17-3, ..., 17-N AD converter 18-1, 18-2, 18-3 ,..., 18-N FIFO memory 19 Write / read control circuit 20 Adder circuit 41 Quantization accuracy selection signal input device 42 Delay quantization amount determination device 43 Transmit beamforming control circuit 44 Receive beamforming control circuit

Claims (6)

A plurality of ultrasonic transducers arranged to transmit or receive ultrasonic signals;
A transmission circuit for supplying drive pulse signals to these ultrasonic transducers via a plurality of transmission / reception changeover switches;
A transmission beamforming control circuit for controlling a delay amount of the drive pulse supplied to the transmission circuit;
A plurality of receiving circuit where the ultrasonic signal the received by the ultrasonic transducers are supplied via the transmission and reception change-over switch,
A reception beamforming control circuit to which the output signals of these reception circuits are respectively supplied,
An ultrasonic diagnostic apparatus having a diagnostic mode for detecting blood flow velocity at a fixed focus,
The reception beamforming control circuit further includes:
An input device ;
A delay quantization amount determining device for determining a delay quantization amount based on the beam thickness selected by the input device;
A quantization circuit that quantizes the delay amount based on the delay quantization amount determined by the delay quantization amount determination device;
A signal delay circuit for imparting a delay amount in which the quantized output signal of the previous SL respective receiving circuits,
An ultrasonic diagnostic apparatus comprising: a signal synthesizer that synthesizes the output signals of the received signals delayed by the signal delay circuit. The quantization circuit also quantizes the delay amount controlled by the transmission beamforming control circuit.
The ultrasonic diagnostic apparatus according to claim 1.   The ultrasonic diagnostic apparatus according to claim 1, wherein an output of the delay quantization amount determination apparatus is also supplied to the transmission beamforming control circuit, and the accuracy of transmission and reception beamforming can be controlled independently of each other. The ultrasonic diagnostic apparatus according to claim 3, wherein the accuracy of the transmission and reception beamforming is selected according to a delay quantization amount determined by the quantization determination apparatus. The ultrasonic diagnostic apparatus according to claim 1, wherein the delay amount of the drive pulse is determined based on a center frequency of the transmitted / received ultrasonic signal and quantization accuracy of the delay amount. A scan is performed with a wide beam width formed by a delay amount quantized with rough quantization accuracy at the start of scanning, and then a scan is performed with a narrow beam width formed by a delay amount quantized with fine quantization accuracy. The ultrasonic diagnostic apparatus according to claim 5.

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