JPH024346A - Ultrasonic measuring device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention transmits ultrasonic waves into a subject, receives reflected waves from within the subject, converts them into received signals, and converts the received signals into received signals. The present invention relates to an ultrasonic measuring device that measures acoustic characteristics within a specimen.

2. Description of the Related Art Conventionally, there is an ultrasonic diagnostic apparatus as a method of obtaining information inside a living body using ultrasonic waves. Most of these ultrasound diagnostic devices use the pulse reflection method, which transmits ultrasonic waves into the living body, receives reflected waves from the living body, and obtains information about the inside of the living body from the reflected waves. There is. This pulse reflection method collects and displays in-vivo information two-dimensionally from the reflected echo intensity from an interface with a difference in acoustic impedance, that is, the amplitude, and the propagation time of the ultrasonic waves. It's worth it. However, in recent years, there has been an increasing demand for ultrasonic diagnostic apparatuses that mainly diagnose the shape of living tissues to obtain information other than the shapes of living tissues. Such information regarding the quality of living tissue can be obtained, for example, by measuring the magnitude of attenuation of ultrasonic waves, the speed of sound, etc., which have specific values in various organs within the living body. As a method for measuring the frequency dependence of the attenuation coefficient of ultrasonic waves, for example, Proceedings of the IEE (
PROCEEDINGS OF THE IEgg
).

VoL 73. N [17, 1985, 1159-11
5D (Sp
ectral difference) method is known.

Below, the conventional SD method will be explained with reference to FIG. FIG. 4 shows an example of an ultrasonic reflected signal. The SD method extracts the different propagation distances of the reflected signal, for example, Dl and D2, using a certain interval window function, such as the No-Mink window, as shown in Figure 4, and analyzes the difference between Dl and D2. This is to find the frequency dependence of the attenuation coefficient between. Assuming that the distance d between the region D1 and the region D2 is constant, and the attenuation characteristic between them is constant, and the frequency dependence of this attenuation coefficient is β (d B / MHz / cm ), the power transfer between the region D1 and the region D2 is Function H
(f) +2 can be expressed as a function of β as shown in equation (1) below.

H(f)12=10-02βfd...
(1) Let Pl(f) and P2(f) be the power spectra calculated from the data extracted by the window of area D1 and area D2, respectively, then the power spectra Pl(f), P2(f) and the power transfer function IH (f)
+2, there is a relationship expressed by the following equation (2).

)((f) +2=P2(f)/PI(f)...
(2) From the above equations (1) and +2, the logarithmic spectrum of the power transfer function IH(f)+2 is as shown in the following equation (3).

101og1o IH(f)12=101ogtoP2
(f)−101ogloPt(fl=−2βfd
...(3) And 101og1oP2101o 101ogto
By determining the slope of P101o with respect to frequency 1, the frequency dependence β of the damping coefficient can be determined.

Problems to be Solved by the Invention As shown in FIG. 4, an ultrasonic received signal attenuates as it propagates through a propagation medium with an attenuation coefficient frequency dependence β (dβ/MHz/(m). For example, In a medium with a frequency dependence β of 0.7 dB /MHz/cm, an ultrasonic signal of /MHz is attenuated by 5.5 dB while reciprocating over a distance of 4 cm.If this linearity is processed only by an amplifier, the signal becomes even deeper. The reflected signal from there becomes weak, and quantization errors in the A/D converter become a problem.

For this reason, conventional ultrasonic diagnostic apparatuses amplify data in a region far from the ultrasonic transducer using logarithmic compression, a variable gain amplifier, etc. that depends on the propagation distance. However, when analyzing a received ultrasonic signal to measure the acoustic characteristics of a propagation medium, the analysis must take into account complex logarithmic compression and the characteristics of a variable gain amplifier.

The present invention solves the above-mentioned problems of the conventional technology, and the quantization error of the A/D converter increases even if amplified by a nonlinear amplifier, in contrast to the decrease in the amplitude value of the ultrasonic reflected signal due to the attenuation medium. It is an object of the present invention to provide an ultrasonic measuring device that can reduce the amount of noise and improve the measurement accuracy of acoustic characteristics in an attenuating medium.

Means for Solving the Problems The technical solution of the present invention for achieving the above object is as follows:
An ultrasonic transducer that transmits ultrasonic pulses to a subject and receives reflected echoes from the subject, a preamplifier that amplifies the received signal of this ultrasonic transducer, and a preamplifier that transmits the output of this preamplifier to multiple propagation regions. a plurality of amplifiers with different amplification factors, at least two A/D converters that perform A/D conversion on the outputs of the plurality of amplifiers; a plurality of memories that store outputs of the plurality of A/D converters; an acoustic characteristic calculation unit that calculates acoustic characteristics from data stored in the plurality of memories; a timing control unit that generates write control signals for the plurality of memories so that areas corresponding to window widths used by the acoustic characteristic calculation unit are stored in an overlapping manner when storing; and displaying the output of the acoustic characteristic calculation unit. The device is equipped with a display section for displaying information.

For production The present invention has the following effects due to the above configuration.

That is, the reflected echo from the object is received by an ultrasonic transducer and converted into a received signal, this received signal is amplified by a preamplifier, and the output of this preamplifier is sent to multiple linear amplifiers corresponding to multiple propagation regions. The signal is amplified by the A/D converter, A/D converted by the A/D converter, and stored in a plurality of memories. At this time, areas corresponding to the width of the window used when analyzing the acoustic characteristics of the propagation medium are stored in an overlapping manner. Therefore, when analyzing the acoustic characteristics between different propagation regions, the effects of linear amplifier switching are not included within the window. Further, data of received signals in a region far from the ultrasonic transducer can also be amplified to an appropriate amplitude by a linear amplifier.

EXAMPLE μ Below, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an ultrasonic measuring device in one embodiment of the present invention. In FIG. 1, l is an ultrasonic transducer that transmits and receives ultrasonic pulses, 2 is a subject whose acoustic characteristics are to be measured, and 3 is a drive that generates a signal to drive the ultrasonic transducer 1. A signal generator 4 is a preamplifier that amplifies the received signal from the ultrasonic transducer 1, 5a and 5b
are first and second amplifiers that linearly amplify the output of the preamplifier corresponding to two propagation regions, and 6a is the first amplifier 5a.
6b is a second A/D converter that A/D converts the output of the second amplifier 5b, and 7a is the first A/D converter. 7b is a second memory that stores the output of the second A/D converter 6b; 8 generates the timing for generating the drive signal of the drive signal generator 3; , 1st. A timing control section 9 generates write and read timings for the second memories 7a and 7b, and a timing control section 9 for generating write and read timings for the second memories 7a and 7b. Second memo 1J73
．． 7b is an acoustic characteristic calculation unit that calculates acoustic characteristics from the data stored; 10 is a storage unit for storing the output of the acoustic characteristic calculation unit 9;
A scan conversion section 11 performs scan conversion, and a display section 11 displays the output of the scan conversion section 10.

There may be three or more sets of linear amplifier 5, A/D converter 6, and memory 7, but since their operations are the same, the first
As shown in the figure, the operation will be explained below for the case where two of each are used.

First, the drive signal generator 3 generates a drive signal to drive the ultrasonic transducer 1. The ultrasonic transducer 1 converts the drive signal into an ultrasonic pulse and transmits the pulse to the subject 2 . The ultrasound pulse propagating through the object 2 is successively scattered while propagating in accordance with the acoustic properties of the tissue, and some of the pulses travel backwards along the propagation path, that is, the acoustic scanning line, and reach the ultrasound transducer 1. and is converted into a received signal. In this process, the ultrasound pulse is influenced by the ultrasound attenuation characteristics and ultrasound scattering characteristics of the tissue of the subject. The received signal, which is the output of the ultrasonic transducer 1, is amplified by the preamplifier 4 and becomes, for example, the received signal waveform shown in FIG. The signal is input to second amplifiers 5a and 5b. In the first amplifier 5a, the signal in the region A, which is a shallow region within the subject 2 in the received signal shown in FIG. is amplified to the extent that it can be used effectively. This amplified received signal is converted into a digital value by the first A/D converter 6a and stored in the first memory 7a. On the other hand, as shown in FIG. 2, the received signal in the region B, which is deeper than the region B, overlaps the region A by the width W of the window used in the acoustic characteristic calculating section 9, and is transmitted to the region A by the second amplifier 5b in the same manner as above. The signal is amplified, converted into a digital value by the second A/D converter 6b, and stored in the second memory 7b. At this time, the amplification factor of the second amplifier 5b is made larger than the amplification factor of the first amplifier 5a, so that the reception level in the region B is about the same as that in the region A, so that each A/D converter 7a , 7b. Further, a write start signal and a write end signal when storing the received signal of area A in the memory 7a and the second memory 7a are also provided.
The timing control unit 8 generates write start and end signals when storing the received signal of area B in area B. These memory control signals are determined by a time relationship synchronized with the drive signal of the drive signal generator 3.

Next, referring to FIG. 3, the first step when calculating the acoustic characteristics in the acoustic characteristics calculating section 9. A method of extracting the received signals stored in the second memories 7a and 7b will be explained.

Figure 3 is 1. Second note IJ7a.

This is a diagram in which the horizontal axis represents the propagation distance of data in area A and area B stored in area 7b, which overlap by window width W. Now, a case will be described in which the acoustic characteristics between a signal extracted with a window width W and a signal separated by a minute distance d are analyzed using, for example, the SD method described in the above-mentioned section of the prior art. First, the acoustic characteristic calculating section 9 sequentially calculates the acoustic characteristics from the shallow region using the received signal of the region A stored in the first memory 7a. For example, D n -2 and D
Dn-2 and Dn-2 using the data in the area n-1
The acoustic characteristics between 1 and 1 are determined, and then the acoustic characteristics between 1 and Dn are determined using the data of Dn-1 and Dn. next D
When determining the acoustic characteristics between n and Dn+1, the area A K
: Since all the data of the part Dn+1 is not included, the part corresponding to Dn and Dn'4-1 is extracted from the received signal of area B stored in the second memory 7b and used, and further data of Dn+1 and Dn+2 is used. Similarly, Dn+1 and Dn+2 are extracted from the received signal of area B stored in the second memory 7b and used when determining the acoustic characteristics between the two.

The propagation distance dependence of the acoustic characteristics thus obtained by the acoustic characteristic calculation section 9 is converted and stored in the scan conversion section 10 and displayed on the display section 11.

As is clear from the above description, according to the present embodiment, two sets of linear amplifiers 5a and 5b and their corresponding A/D
It has converters 6a, 6b and memories 7a, 7b, and stores the received signals in the respective memories 7a, 7b in duplicate by the width of the window used. In order to reduce the quantization error,
Acoustic characteristics can be determined with high accuracy by eliminating the effects of amplifier switching.

In the above explanation, when comparing Dn and Dn+1 shown in FIG. 3, both data are extracted from the received signal of area B, but if the amplitude information is not compared, D, even if extracted from area A. good. In addition, the data section d extracted in the window W is explained as d(W in FIG. 3, but d>W may also be used.
Three or more sets of D converters and memories may be used; in this case,
The number of A/D converters may be two, and the first A/D converter and the second A/D converter may be divided into odd-numbered and even-numbered regions and switched and operated.

Effects of the Invention μ As described above, according to the present invention, a received signal is linearly amplified corresponding to a plurality of propagation regions, and a plurality of linear amplifiers with different amplification factors are used, and the outputs of the plurality of amplifiers are A/D-amplified. at least two A/D converters for converting, and a plurality of memories corresponding to the plurality of propagation regions and storing outputs of the plurality of A/D converters, and receiving amplified and digitally converted. When storing signals in each memory, areas corresponding to the widths of the windows used to calculate the acoustic characteristics in the acoustic characteristic calculation section are made to overlap. As a result, when analyzing the acoustic characteristics between different propagation regions, the effects of linear amplifier switching are not included within the window.

Further, data of received signals in a region far from the ultrasonic transducer can also be amplified to an appropriate amplitude by a linear amplifier. Therefore, the influence of quantization errors of the A/D converter can be reduced, and the accuracy of measuring acoustic characteristics can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an ultrasonic measuring device according to an embodiment of the present invention, FIG. 2 is a diagram showing the waveform of the received signal amplified by the preamplifier of the above embodiment and the propagation region stored in the memory, and FIG. The figure is an explanatory diagram of the calculation operation of the acoustic characteristic calculation unit of the above embodiment, and FIG. 4 is an ultrasound reflection signal waveform diagram for explaining the conventional ultrasound measurement device. DESCRIPTION OF SYMBOLS 1... Ultrasonic transducer, 2... - Subject, 3... Drive signal generation part, 4... Preamplifier, 5a, 5b... Linear amplifier, 5a, 5b --- A/D conversion Vessel, 7a, 7b
-Memory, 800. Timing control unit, 9...Acoustic characteristic calculation unit, 10,...Scan conversion unit, 11...Display unit. Name of agent: Patent attorney Toshio Nakao (1 person) Figure Figure J Ni! It's me t 1 power and 3 ot, tiger and beast rogu l th; Kuyumi 2-
Memo force 2 power / pηru 41 danger rai〉) 7 width ε

Claims (1)

[Claims] An ultrasonic transducer that transmits ultrasonic pulses to a subject and receives reflected echoes from the test waves, a preamplifier that amplifies the received signal of this ultrasonic converter, and a preamplifier that transmits the output of this preamplifier to multiple propagation regions. a plurality of amplifiers with different amplification factors, corresponding to the plurality of propagation regions, at least two A/D converters that A/D convert the outputs of the plurality of amplifiers; a plurality of memories that store outputs of the plurality of A/D converters; an acoustic characteristic calculation unit that calculates acoustic characteristics from data stored in the plurality of memories; and a timing control unit that generates a write control signal for the plurality of memories so that areas corresponding to window widths used in the acoustic characteristic calculation unit are stored in an overlapping manner when storing the ultrasound. Measuring device.