JPH0723950A - Ultrasonic wave signal receiving method and ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To provide an ultrasonic wave diagnostic device of simple circuit constitution and low cost by applying phase arrangement and addition, and orthogonal wave detection to RF echo signals converted into digital data to reduce a frequency to a base band frequency zone. CONSTITUTION:When an ultrasonic wave is transmitted from a transmission part 1 through an ultrasonic probe 2 to a sample diagnosis part 3, RF echo signals are obtained from zones of different sound impedances in the sample diagnosis part 3 to get into an A/D converter 5 to be converted into digital data. The converted RF echo signals are delayed for specified quantity by respective digital delay lines 6, so phase-arranged signals are provided and added by an adder 47 to get into a base band detection part 50. An output of a multiplier 51 is outputted from a low-pass filter 53 as a Q-component, and an output of a multiplier 52 is outputted from a low-pass filter 54 as an I-component. The RF signals outputted from the base band detection part 50 is dropped to a base band frequency having a DC at a center.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic wave reception processing method and an ultrasonic diagnostic apparatus.

[0002]

2. Description of the Related Art RF (Radio Frequency)
y) In the case of the digital beam former of the system, the echo signal after delay addition is transferred to a processing system such as log compression, envelope detection or quadrature detection. The transfer rate at this time needs to be a frequency equal to the sampling rate of the A / D converter. That is, the bus having the word width of the echo signal becomes high frequency, which causes high frequency noise. In order to avoid the transfer at this high frequency, the beam former drops to the baseband after delay addition. As a result, the transfer rate can be reduced to about twice the bandwidth of the echo signal.

FIG. 6 is a block diagram showing a configuration example of a conventional device. When an ultrasonic wave is transmitted from the transmission unit 1 to the subject diagnostic unit 3 via the ultrasonic probe 2, RF (Radio Fr.
The echo signal is obtained. This RF echo signal is obtained for each sound ray. Here, as many RF echo signals as the number of sound rays (the number of transducers of the probe) n are amplified by each amplifier 4, then enter the A / D converter 5, and are converted into digital data. (It should be noted that, depending on the device, there is a configuration in which the RF echo signal is set to less than n by a cross point switch, a phasing primary delay line, or the like.

The RF echo signal converted into digital data is delayed by a predetermined amount by each digital delay line 6. Then, from the output of each digital delay line 6, signals with uniform phases are obtained. The outputs of these digital delay Latins 6 are added by each adder 7. Then, the final adder 7 obtains an added signal of all digital echo signals. The reason why such an addition method is adopted is that the control is simple.

The full addition signal enters another printed board through the jumper wiring 8. The reason is that the size of a printed board having a limited area (usually about 30 cm ² ) fills up the digital delay line section. One of the inputs enters a TFC filter (bandpass filter with variable passband) 9. This TFC
(Time Frequency Control)
The filter 9 works as follows. That is, the frequency of the signal reflected from the subject diagnostic unit 3 decreases in proportion to the depth of the subject diagnostic unit 3. Therefore, the center frequency of the passing frequency is changed according to the change in the frequency of the received RF echo signal. By doing so, an accurate RF echo signal at the received frequency can be obtained. The RF echo signal that has passed through the TFC 9 is logarithmically compressed by the log converter 10 and then subjected to processing such as envelope detection and is displayed as a B-mode image on a display unit (not shown).

On the other hand, the RF echo signal input via the jumper wiring 8 enters the quadrature detection section 20. Quadrature detector 2
At 0, the multiplier 21 multiplies the input signal by cos ωt, and the multiplier 22 multiplies the input signal by sin ωt. In this way, the signals multiplied by the sin wave and the cos wave which are 90 ° out of phase are respectively filtered by the filter 2
It is output after being filtered by 3, 24. Here, the output of the filter 23 is in-phase (INPHAS
E, hereinafter abbreviated as I) signal, and the output of the filter 24 becomes a quadrature (QUADRATURE, hereinafter abbreviated as Q) signal. These I signal and Q signal are subjected to Doppler processing to extract phase information.

FIG. 7 is a configuration block diagram showing another embodiment of the conventional device. The same parts as those in FIG. 6 are designated by the same reference numerals. When an ultrasonic wave is transmitted from the transmitting unit 1 to the subject diagnostic unit 3 via the ultrasonic probe 2, an RF echo signal is obtained from a region of the subject diagnostic unit having different acoustic impedance. This RF echo signal is obtained for each sound ray. Here, as many RF echo signals as the number of sound rays (the number of transducers of the probe) n are amplified by each amplifier 4, then enter the A / D converter 5, and are converted into digital data.

The output of each A / D converter 5 enters the quadrature detector as it is. That is, they enter the multipliers 41 and 42, respectively, and are multiplied by cos ωt and sin ωt. The multiplied echo signal is output from the low pass filter 43 as an I signal and from the low pass filter 44 as a Q signal. Therefore, in the case of this embodiment, the quadrature detector 40 drops the signal to the baseband frequency region, and the subsequent signals are low frequency signals. The outputs of the low-pass filters 43 and 44 enter the digital delay line 6 for phase adjustment.

The phase-adjusted delay line output for each sound ray is added by adders 45 and 46 for each I line segment and Q component.
Enter and get added. Here, the configuration of each of the adders 45 and 46 is the same as that of the adder 7 of FIG. The addition results of the adders 45 and 46 enter the TFC unit 30. The outputs of the adders 45 and 46 enter the phase shifter 31 for phase shift, and the frequency is adjusted. The RF echo signal whose frequency has been adjusted by the phase shifter 31 is passed through low pass filters 32 and 33, which are I signal and Q signal, respectively.
It is output as a signal. Here, the phase shifter 31 moves the pass band of the filter as the frequency of the reflected echo signal decreases, as described in the TFC 9 of FIG. As a result, the optimum RF echo signal in which only the target frequency component has passed can be obtained from the filters 32 and 33.

[0010]

In the conventional example shown in FIG. 6, the entire system must operate with the sampling clock of the A / D converter 5. At that time, the TFC filter 9 must also operate at high speed, and it is necessary to use an element capable of operating at high speed, which increases cost and complicates the configuration. Furthermore, the part of the adder 7 and the TFC filter 9
Since the wiring is connected to the portion by the jumper wiring 8, there is a problem that this jumper wiring operates as an antenna and picks up electromagnetic wave noise in a circuit in which high-speed signals fly, and is weak against noise.

Further, in the conventional example shown in FIG. 7, since the conversion data by the A / D converter 5 is directly put into the quadrature detection section 40 and dropped in the baseband frequency range, it is less susceptible to noise. Since it is necessary to provide circuits for I and Q systems for each channel, there is a problem that the circuit configuration becomes complicated and the cost becomes high.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultrasonic wave reception processing method and an ultrasonic diagnostic apparatus having a simple circuit configuration and low cost.

[0013]

According to the present invention for solving the above-mentioned problems, a received signal corresponding to each vibrating element of a probe is converted into digital data (step 1), and the converted digital data of each channel is converted. It is characterized in that the phases are adjusted and added (step 2), the added digital data is quadrature detected, and the frequency is dropped to the baseband frequency region (step 3).

[0014]

First, the RF echo signal converted into digital data is passed through a delay line to perform phasing addition. Then, the RF echo signals subjected to the phasing addition are subjected to quadrature detection to drop the frequency down to the baseband frequency region. With this configuration, the digital delay lines for the I component and the Q component are not required for each sound ray, and the circuit is simplified. In addition, since the baseband is converted first, the frequency to be handled becomes a low frequency, so that it is not necessary to use a high-speed element. Further, high frequency noise is not generated and the noise characteristic is improved. As described above, according to the present invention, it is possible to provide an ultrasonic wave reception processing method and an ultrasonic diagnostic apparatus that have a simple circuit configuration and are inexpensive.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a flow chart showing the principle of the method of the present invention, and FIG. 2 is a block diagram of the principle of the present invention. 2, the same parts as those in FIGS. 6 and 7 are designated by the same reference numerals. In the figure, 1 is a transmitter that emits ultrasonic waves, 2 is an ultrasonic probe that transmits and receives ultrasonic waves, and 3 is a subject diagnostic unit. Reference numeral 5 is an A / D converter that receives an RF echo signal of each ultrasonic transducer and converts it into digital data, 6
Is a digital delay line for adjusting the phase of each output of these A / D converters 5.

Reference numeral 47 is an adder for adding the outputs of the respective digital delay lines 6, and reference numeral 50 is a baseband detector for receiving the output of the adder 47 and performing quadrature detection. The specific configuration of the adder 47 is the same as that of the adder 7 shown in FIG. The baseband detection unit 50 uses, for example, an RF echo signal having a center frequency of 3.5 MHz as a center frequency of 0 (direct current).
Convert to baseband.

In the baseband detector 50, 51 is a multiplier for multiplying an input signal by sin ωt, and 52 is a multiplier for multiplying an input signal by cos ωt. 53 is a low pass filter (LPF) for receiving the output of the multiplier 51,
Reference numeral 4 is a low-pass filter that receives the output of the multiplier 52. The output of the low-pass filter 53 becomes the Q component, and the output of the low-pass filter 54 becomes the I component. The operation of the apparatus configured as described above will be described below.

When an ultrasonic wave is transmitted from the transmitting unit 1 to the subject diagnostic unit 3 via the ultrasonic probe 2, an RF echo signal is obtained from a region of the subject diagnostic unit having different acoustic impedance. This RF echo signal is obtained for each sound ray. Here, RF of the number of sound rays (the number of transducers of the probe) n
The echo signal enters the A / D converter 5 and is converted into digital data. Depending on the device, the cross point switch and the phasing primary delay line, etc.
The F echo signal may be less than n.

The RF echo signal converted into digital data is delayed by a predetermined amount by each digital delay line 6. Then, from the output of each digital delay line 6, signals with uniform phases are obtained. The outputs of these digital delay Latins 6 are added by the adder 47. The specific configuration of the adder 47 is
The configuration is the same as that of the adder 7 shown in FIG. The output of the adder 47 enters the baseband detector 50.

In the baseband detector 50, the adder 47
The outputs of the two inputs to the multipliers 51 and 52, respectively. Multiplier 51
In, the input signal is multiplied by sin ωt, and in the multiplier 52, the input signal is multiplied by cos ωt. The output of the multiplier 51 is output as a Q component from the low-pass filter 53,
The output of the multiplier 52 is output from the low pass filter 54 as an I component. Here, the RF echo signal output from the baseband detection unit 50 is dropped to the baseband frequency whose center is DC. As a result, the bandwidth can be reduced to about twice the bandwidth of the echo signal.

FIG. 3 is an explanatory diagram of baseband detection.
(A) is a frequency spectrum centered on 3.5 MHz, and this frequency spectrum is converted into the baseband region as shown in (b). Therefore, the information component is included around the origin 0 and the frequency is lowered.

According to the present invention, since the frequency of the RF echo signal becomes low, even when the jumper wirings 55 and 56 are provided at the output of the baseband detecting section 50 as shown in FIG. Since it has a low frequency, it is not affected by electromagnetic noise. That is, it is resistant to noise. Further, since the quadrature detection is performed after passing through the digital delay line 6, there is no need for a digital delay line for each I component and Q component, and the circuit is simplified. 3 (I ² + Q ² ) from the obtained I and Q components
^1/2 calculation is performed, logarithmic compression is performed, and B mode image is displayed. In the case of Doppler information, MTI processing or the like is performed using the I and Q components as they are.

FIG. 4 is a block diagram showing the configuration of an embodiment of the present invention. The same parts as those in FIG. 2 are designated by the same reference numerals. In the figure, 4 is the RF received by each ultrasonic transducer
It is an amplifier that amplifies the echo signal to a predetermined amplitude. The outputs of these amplifiers 4 are input to the A / D converter 5. The output of each A / D converter 5 enters the corresponding digital delay line 6 and is data-delayed.
And in the output of each digital delay line 6,
The phases will be perfectly aligned.

The RF echo signals whose phases are aligned are added by the adder 47, and then enter the baseband detector 50. Here, the multiplier 51 uses the input signal and sin ((ωt)
.Multidot.t), and the multiplier 52 multiplies the input signal by cos ((ω
Multiply t) · t). Here, ωt of these trigonometric functions
Is a correction term for the variation from the center frequency, and t is the time component of normal quadrature detection. With such a configuration, even when the center frequency fluctuates up and down around 3.5 MHz, for example, it is possible to perform frequency conversion into a base band in which the fluctuation is corrected. These converted RF echo signals are output to the subsequent low pass filters 53, 54.
After entering and noise is removed, it is output as a Q component and an I component, respectively.

FIG. 5 is a block diagram showing another example of the configuration of the baseband detecting section 50. Here, ω (t) = ω +
Let us consider it as Δω (t).

The outputs of the adders 47 are the multipliers 6 respectively.
1, 62 and multiplied by cos ωt and sin ωt. The output of the multiplier 61 enters the multiplier 63, and the variation s
It is multiplied by inΔωt, and also enters the multiplier 64, and is multiplied by the fluctuation component cosΔωt. The output of the multiplier 62 enters the multiplier 65 and is multiplied by cos Δωt, and the multiplier 66
And is multiplied by sin Δωt.

Then, the output of the multiplier 63 and the output of the multiplier 65 are added by an adder 67 to form an I component. Further, the output of the multiplier 64 and the output of the multiplier 66 are added by the adder 68 to form a Q component. The outputs of the adders 67 and 68 are output via the low pass filters 53 and 54, respectively. Even with such a configuration, the conversion to the base band can be performed while considering the influence of the frequency decrease in the depth direction of the diagnostic unit.

As described in detail above, according to the present invention, since the delay addition is performed as the RF system, a compact system can be realized. Further, since the baseband detection is performed after the delay addition, the transfer speed of the data bus between the print boards can be suppressed to some extent low. Further, TFC can also be realized by a low-pass filter that has a fixed frequency shift.

[0029]

As described above, according to the present invention, an ultrasonic wave reception processing method and an ultrasonic diagnostic apparatus having a simple circuit configuration and a low cost are provided by performing quadrature detection on the delayed and added RF echo signals. be able to.

[Brief description of drawings]

FIG. 1 is a flow chart showing the principle of the method of the present invention.

FIG. 2 is a principle block diagram of the present invention.

FIG. 3 is an explanatory diagram of baseband detection.

FIG. 4 is a configuration block diagram showing an embodiment of the present invention.

FIG. 5 is a configuration block diagram showing another embodiment of the baseband detection unit.

FIG. 6 is a block diagram showing a configuration example of a conventional device.

FIG. 7 is a block diagram showing another configuration example of a conventional device.

[Explanation of symbols]

 1 Transmitter 2 Probe 3 Subject Diagnosis Unit 5 A / D Converter 6 Digital Delay Line 47 Adder 50 Baseband Detector 51,52 Multiplier 53,54 Low-pass Filter 55,56 Jumper Wiring

Claims (2)

[Claims] 1. A received signal corresponding to each vibrating element of a probe is converted into digital data (step 1), the phase of the converted digital data of each channel is adjusted and added (step 2), and added. An ultrasonic wave reception processing method characterized in that quadrature detection of digital data is performed and the frequency is dropped to the baseband frequency region (step 3). 2. An ultrasonic diagnostic apparatus in which an ultrasonic wave is applied to a subject, and a reflection signal from the subject is received and displayed as an ultrasonic image. Add the A / D converter (5) that converts the wave signal to digital data, the digital delay line (6) that adjusts the phase of the converted digital data of each channel, and the outputs of these digital delay lines (6) And an adder (47) for performing a quadrature detection to reduce the frequency to a baseband frequency region by receiving the output of the adder (47). Diagnostic device.