JPH03143432A - Dispersion compression type ultrasonic diagnostic apparatus - Google Patents

Abstract

PURPOSE:To perform an imaging wherein unnecessary components due to time side rope etc., are sufficiently suppressed by analyzing a specified watching range of a wave receiving signal, obtaining tentatively a responding characteristics of a constituting system, calculating an optimum charp signal and a kernel for compression and measuring a wave receiving signal. CONSTITUTION:A probe 8 is driven by means of a signal having a specified step function to obtain a wave receiving signal as an output of an amplifying part 9 and it is input in a CPU 1 through an A/D converter 10 and a buffer memory 11 and the CPU 1 performs a frequency analysis on the watching range of the signal. The wave shape of the transmitted wave is a wave shape obtd. on the original time axis by 1FFT wherein a complex spectrum in a selected frequency range, as the result, with a length obtaining a required TB product is multiplied with a reciprocal of an amplitude and a phase characteristics. However as this does not include avodization, it is furthermore, for example, multiplied with an avodization on a time axis of COS<2> type.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ultrasonic diagnostic apparatus, and particularly to dispersion compression thereof.

[Prior art] Conventional distributed compression type ultrasound diagnostic equipment uses linear FM
The only way to obtain an image of the subject was by sending and receiving chirp signals and compressing them.

However, the system of the structure of the round-trip signal including the echo source when viewed from the probe terminal has frequency characteristics and phase characteristics, and under these constraints, obtaining the optimal compression result requires a more complicated system. Processing is required.

For example, amplitude avoidization on the time-frequency axis is essential for reducing time side lobes, but its functional form is such that it is reduced from time side lobes with respect to the characteristics of the entire system including the probe and echo source. Must be set.

However, in the conventional design policy, processing has been carried out from the viewpoint that it is sufficient to simply equalize the frequency characteristics and phase characteristics of the system.

[Problems to be Solved by the Invention] In the conventional dispersion compression type ultrasonic diagnostic apparatus as described above, as described above, according to the conventional design policy, the time sidelobes are minimized or There is a problem in that the time side lobe may be deteriorated depending on the characteristics of the target area or the echo source therein because it is not optimized.

This invention was made in order to solve these problems, and it performs abodization that is optimized by incorporating the characteristics of the entire system such as the probe, medium, echo source, etc. The purpose of this invention is to obtain an ultrasonic diagnostic apparatus using a dispersion compression method that can reduce time side lobes using such a method.

[Means for Solving the Problems] The distributed compression type ultrasound diagnostic apparatus according to the present invention analyzes the attention section of the received signal to determine the response characteristics of the component system for obtaining the image of the subject. It is equipped with means for experimentally determining the optimum chirp signal and compression kernel based on the response characteristics, and means for measuring the received signal using the chirp signal and the compression kernel. be.

Further, the received signal is measured for each depth according to the depth of the echo source from the subject.

In addition, the center frequency and bandwidth of the component system are calculated, the chirp width on the frequency axis is determined according to the calculated center frequency and bandwidth, and the time of the chirp signal that has a predetermined TB product according to the chirp width is determined. After calculating the width, the frequency characteristics and phase characteristics of the constituent system are removed from the necessary avodization to perform predetermined avodization.

[Operations] In this invention, a predetermined section of interest of the received signal is analyzed, the response characteristics of the constituent system are determined on a trial basis, and the optimal chirp signal and compression kernel are calculated based on the response characteristics. .

Then, the received signal is measured using the calculated chirp signal and compression kernel.

In addition, depending on the depth of the echo source from the subject, the section of interest of the received signal is analyzed for each depth, the response characteristics of the component system are determined on a trial basis, and based on the response characteristics, the optimal Calculate the chirp signal and compression kernel.

Then, the received signal is measured using the calculated chirp signal and compression kernel.

In addition, the center frequency and bandwidth of the component system are calculated, the chirp width on the frequency axis is determined according to the calculated center frequency and bandwidth, and the time of the chirp signal that has a predetermined TB product according to the chirp width is determined. After calculating the width, the frequency characteristics and phase characteristics of the constituent system are removed from the necessary avodization to perform predetermined avodization.

Embodiment FIG. 1 is a schematic diagram of a distributed compression type ultrasonic diagnostic apparatus showing an embodiment of the present invention.

(1) is a CPU having a memory, is equipped with a frequency analysis means, and executes a predetermined process to be described later. (
2) is a display that displays images based on signals from CPU (1).

(3) is a realfim controller that drives a predetermined circuit section based on instructions from the CPU (1);
4) is a buffer memory that stores and outputs the transmission signal output from CPU (1), and (5) is a D/D converter that converts the transmission signal from buffer memory (4) into an analog signal.
A converter, (6) is an amplification unit that amplifies the transmission signal from the D/A converter (5), and (7) is a real-time controller (
3) is a transmitting/receiving switching unit that outputs a transmitted signal or receives a received signal based on the signal from.

<8) is a probe that emits a transmitting signal according to a signal having a predetermined step function from the transmitting/receiving switching unit (7), receives the echo, and converts it into an electrical signal as a receiving signal and switches the transmitting/receiving. It is output to section (7). (9) is an amplification unit that amplifies the reception signal output from the transmission/reception switching unit (7);
((0) is an A/D converter that digitally converts the received and transmitted signals output from the amplifier (9), and (11) stores and outputs the digitized received and transmitted signals from the A/D converter. It is buffer memory.

FIG. 2 is a waveform diagram illustrating the received signal, in which the echo is received by the probe (8), the transmission/reception switching section (7) and the amplification section (9).
) is the received signal obtained through.

The operation of the distributed compression type ultrasonic diagnostic apparatus configured as described above will be described below.

The probe (8) is driven with a signal having a predetermined step function to obtain the received signal shown in FIG. (11) to CPU (1), CPU
In (1), assume that the frequency analysis of the section of interest shown in FIG. 2, for example, of the signal is performed to obtain, for example, the spectrum characteristics described below.

Figure 3 is a diagram explaining the spectrum characteristics, which means the transmission characteristics including all the frequency characteristics of the system due to the probe (8), the transmission/reception switching section (7), and the echo source in the area of the target object. It is something to do.

Further, the dotted line indicates the phase characteristic, and the phase characteristic is calculated in addition to the frequency characteristic, the linear component is removed, and the curved component is indicated.

Using the spectrum characteristics shown in FIG. 3, the section in which the frequency is used (hereinafter referred to as the section in use) is determined.

However, the section (a) in FIG. 3 is too narrow, resulting in the loss of an unused section.

Further, equalization cannot be easily achieved in the section (C). In other words, the amplitude modulation component of the bri-equalized transmission signal becomes too large, resulting in poor efficiency.

Therefore, it is most efficient to divide the round trip loss by approximately 6 dB, for example, as in the section (b) of FIG. 3.

Alternatively, it is also good to create a pre-equalized transmission signal on a trial basis, make a determination, and then try again.

FIGS. 4(a) and 4(b) are pre-equalized linear chirp signals.

This transmitted waveform is of the selected frequency interval and as a result (the maximum value is planned, and the time width within it)
Prepare a complex spectrum with a length to obtain the desired TB product (or prepare a signal in the form of such a spectrum), multiply it by the reciprocal of the amplitude and phase characteristics of the system obtained above, and then use IFFT to obtain the original signal. This is a waveform obtained on the time axis.

However, this does not include avodization, so avodization on the time axis of CO52 type, for example, is further applied.

FIG. 5 is a diagram showing the waveform of an avocized FM chirp, which is a wave that has been subjected to avocization on the time axis of the linear C082 type.

This is simply an ideal kernel for sliding convolution integration of the echo signal received via the probe (8) during reception, etc. This is the same CO32 type avodization as the near FM chirp signal. You can use the one that has been done.

Furthermore, the above noted sections are performed separately for each depth of the object,
It would be even better if the resulting image could be edited into a single completed image.

Further, the waveforms shown in FIGS. 4 and 5 are stored in the memory of the CPU (1).

[Effects of the Invention] As described above, according to the present invention, a predetermined attention section of the received signal is analyzed, the response characteristics of the component threads are determined on a trial basis, and the optimal chirp signal is determined based on the response characteristics. Since the received signal is measured by calculating the compression kernel and the compression kernel, the effect of imaging is obtained in which unnecessary components such as time side lobes are sufficiently suppressed.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a distributed compression type ultrasonic diagnostic apparatus showing an embodiment of the present invention, FIG. 2 is a waveform diagram explaining a received signal, FIG. 3 is a diagram explaining spectrum characteristics, and FIG. 4
Figures (a) and (b) are diagrams showing pre-equalized and near-chirp signals, and Figure 5 is a diagram showing the waveform of an avocized FM chirp. In the figure, (1) is a CPU with memory. (2) is the display, (3) is the real-time controller, (4) is the buffer memory, (5) is the D/A converter, (6) is the amplifier, (7) is the transmit/receive switch, and (8) is the detector. Tentacle, (9) is the amplification section, (10) is the A/D converter, <II
) is the buffer memory.

Claims (3)

[Claims] (1) In an ultrasonic diagnostic apparatus that drives a probe to emit ultrasonic waves to a subject, converts the echoes into electrical signals, and compresses a received signal to obtain an image of the subject, the received signal means for experimentally determining response characteristics of a constituent system for obtaining an image of the subject by analyzing the attention section of the object; and means for calculating an optimal chirp signal and compression kernel based on the response characteristics. , means for measuring the received signal using the chirp signal and a compression kernel. (2) The dispersion compression type ultrasonic diagnostic apparatus according to claim 1, wherein the received signal is measured for each depth according to the depth of the echo source from the subject. (3) Calculate the center frequency and bandwidth of the component system, determine the chirp width on the frequency axis according to the calculated center frequency and bandwidth, and create a chirp signal that has a predetermined TB product according to the chirp width 2. The dispersion compression type ultrasonic diagnostic apparatus according to claim 1, wherein after calculating the time width, the frequency characteristics and phase characteristics of the component system are removed from the necessary avodization to perform predetermined avodization.