JPS6133647A - Brightness correction circuit of doppler display - 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 relates to a brightness correction circuit for performing Doppler display in an ultrasonic diagnostic apparatus having a Doppler mode display function.

FIG. 6 shows the principle of Doppler display in an ultrasonic diagnostic apparatus having a Doppler mode display function.

FIG. 6(A) is a block diagram showing a processing circuit for the Doppler display, and FIG. 6(B) is a diagram showing the processing process of the Doppler display at a certain time.

First, an echo signal (Doppler shift signal) from the blood flow at the Doppler measurement site received by the ultrasound probe 1 is converted into a multi-bit digital signal by an analog/digital converter (A/D) 2, This digital signal is used for FFT analysis to obtain a power spectrum data string for the frequency component of the echo signal.

In reality, for example, 64/128 ultrasonic pulse signals are emitted within a unit time, and 64/128 echo signals obtained are subjected to wave number analysis using an FFT analysis analyzer. A power spectrum data sequence for frequency components of an echo signal is obtained.

When converting this power spectrum data string to the luminance intensity of a display device (TV>6), human visual characteristics.

In accordance with the brightness characteristics of the cathode ray tube, the brightness converter 4 converts the power spectrum data string into a brightness data string using a conversion function such as logarithmic conversion, and converts the power spectrum data string into a brightness data string in the frame memory.
RAM) Write to 5.

Doppler measurement can be performed by reading out the digital value of the echo signal written in the frame memory (RAM) 5 using a standard television system and displaying it on the display device (TV) 6.

Note that the writing of the luminance conversion data string to the frame memory (RAM) 5 and the reading for display are performed in a time-division manner.

The above display process is shown in (b). In this figure, (a)
indicates the output data of the FFT analyzer 3, and the horizontal axis is the frequency f
, the vertical axis shows the power spectrum P, where Pi· is the peak value and P max is its maximum value. (b) shows an example of brightness conversion using a logarithmic curve, where the horizontal axis shows the power spectrum data; the axis shows the brightness level I; Pi, I
i is each peak value. (c) is a display example on the display device (TV) 6, in which the horizontal axis indicates time t, and the vertical axis indicates luminance-modulated power spectrum data f.

Doppler display at a certain time is obtained by frequency-analyzing 64/128 echo signals obtained within the above unit time using the FFT analyzer 3 shown in FIG.
→Displayed on the display device (TV) 6 in the order of (c).

As shown in FIG. 7, when the display brightness of the power spectrum data string obtained in this way is low overall [
There is a high case [see FIG. 7(b)] and a high case [see FIG. 7(b)].

If the overall brightness is low, the brightness will be displayed in a weak manner, and if it is high, the brightness will be displayed on the verge of saturation.In either case, there is a problem in that the brightness is difficult to see, and an effective display method has been desired.

[Conventional technology]

A conventional technique for solving the above problems is shown in FIG.

In this figure, 1 to 6 are the same as those explained in FIG. 6, and 7 is an automatic gain control unit (AGC) that is commonly used in the past. This method performs automatic gain control (ie, AGC) on the signal (analog signal) itself so that weak echo signals are strengthened and strong echo signals are suppressed.

[Problem that the invention seeks to solve]

The method using the automatic gain control unit (AGC) 7 involves analog processing, so it is generally difficult to control and requires adjustment of the gain level, which has disadvantages in terms of reliability and cost.

In view of the above conventional drawbacks, the present invention provides a method for performing brightness correction on a power spectrum data string obtained by, for example, an Ff'T analyzer after converting a Doppler echo signal at a certain time into a digital signal. The purpose is to

[Means for solving problems]

The purpose of this is: (1) In an ultrasound diagnostic apparatus having a Doppler mode display function, correct and display the power spectrum so that the peak value of the brightness data indicating the power spectrum of the Doppler display becomes the maximum brightness. .

(2) In an ultrasonic diagnostic apparatus having a Doppler mode display function, the power spectrum of the Doppler display is corrected and displayed so that the average value of the brightness data indicating the power spectrum becomes a constant brightness.

This is achieved by the method of the invention.

[Effect]

That is, according to the present invention, the blood flow velocity of the living body is Doppler measured, the echo signal is converted into a digital signal, the frequency analysis is performed with an FFT analyzer, the power spectrum of the echo signal is determined, and then the echo signal is directly or after performing luminance conversion such as logarithmic conversion, the peak value or average value of the digital signal is calculated, the digital signal stored in the frame memory is corrected, and the digital signal is input to the display device. Therefore, it is possible to relatively easily and economically perform a Doppler display that matches the strength of the Doppler echo signal.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1(a) is a block diagram showing one embodiment of the present invention, FIG. 1(0) is a block diagram showing another embodiment of the present invention, and FIG. It is the same as explained in.

First, the embodiment shown in FIG. 1(A) includes a peak detector 8 that detects the peak value (maximum value) Pi of the output of the FFT analyzer 3 or the output of the luminance converter 4 (indicated by a dotted line) P; Based on the detected peak value Pi, frame memory (RAM
) A brightness adjuster 9 is provided to correct the output data (digital value) from 5, detects the peak value Pi of the power spectrum data string (or the brightness converter output of the data string) at a certain time, and determines whether this value is Display device (TV) 6 displays the image at maximum brightness.

Details of the peak detector 8 are shown in FIG. 2(A).

゛ In this peak detector 8, the maximum value set register 82 is reset by a reset signal every 64/128 power spectrum data strings P, and input data is input every clock until the next reset signal arrives. A certain power spectrum data string P is input as B to the comparator 81 and the maximum value cent register 82, and the comparator 81 compares it with the output A of the maximum value set register 82, and A<B is detected. Then, set the value of B at that time as the maximum value in the maximum value set register 82, and repeat the same operation to detect the maximum data Pi among the 64/128 power spectrum data strings P. It functions as follows.

FIG. 2 (J is a time chart showing the above peak value detection operation; (a) is an input power spectrum data string P; FIG.

(b) is a clock.

(c) is a reset signal.

(d) is the output data Pi+ of the maximum value cent register 82
It shows.

In this figure, the third data among the 64/128 pieces of data P has a maximum value of 80, and this value is stored and held in the maximum value cent register 82, and is activated by the next reset signal to be described later. It operates so that the brightness is sent to the brightness adjuster 9.

Next, an example of the brightness adjuster 9 is shown in FIG. 3(A).

In the brightness adjuster 9, corresponding to a frame memory (RAM) 5 that stores output data of the brightness converter 4,
The peak value Pi, which is the output data of the peak detector 8, is transferred to another memory (RAM') by the aforementioned reset signal.
)91 and hold it.

Then, the conventional luminance-converted frame memory (RAM)
) The output data I of 5 and the maximum value Pi of the power spectrum data string P at that time are read out when displayed on the display device (TV) 6, and the data string 1 (64/128 pieces) is read out.
After the adjustment amount I'' for each data I is sequentially determined from the maximum value Pi and the adjustment amount I'' by the adjustment amount calculator 92, the adjustment amount l'' and the conventional luminance data I are added to the adder (+) 9.
3, the brightness is adjusted and the result is used as display data for the display device (TV) 6.

The relative relationship between the above adjustment amount Bi, the output data I of the frame memory (RAM) 5, and the peak value Pi is schematically shown as a three-dimensional graph shown in FIG. 3(b).

That is, the peak value Pi is the power spectrum data string P.
The adjustment amount I' is made smaller as the maximum value P max approaches, and as the peak value Pi becomes lower, the adjustment amount I' is made larger. When the peak value Pi is close to the "0" level, the power spectrum Since this means that the data value itself is low, the adjustment amount B should also be made small to avoid picking up noise, etc. Also, the frame memory (IIAM
) Even when the output data 5 is at a low level, the adjustment amount 1' needs to be small for the same reason.

By performing such correction, display data suitable for the value of the input cover-worth vector data string P can be obtained.

Note that the adjustment amount calculator 92 uses [frame memory (RA)].
It can also be realized with a read-only memory (ROM) in which the address is the output data of M) 5 + peak value Pi).

Next, another embodiment will be described with reference to FIG. 1(b).

In this embodiment, an average value calculator 10 for calculating the average value It of the output of the FFT analysis analyzer (indicated by a dotted line) or the output of the luminance converter 4 is used. A brightness corrector 11 is provided that performs brightness correction based on the average value rt, and when the overall brightness is too low, it is corrected to increase the brightness, and conversely, when the overall brightness is too high, the brightness is corrected. The display is performed so that the entire image has a constant brightness by lowering the brightness.

Details of the average value calculator 10 are shown in FIG. 4(a).

In the average value calculator 10, first, the addition value cent register 101 is reset by a reset signal, and then,
The power spectrum data string (64/128 pieces) that is the output of the PFT analyzer 3 or the data string I obtained by luminance conversion is input to the adder 102 for each clock, and the added value set register 101 is inputted for each data. Add with the output of
To set the result in the added value set register 101, so-called sequential addition is performed on all the data in the data string It operates to send the signal to the corrector 11.

A time chart showing the operation of the average value calculator 10 is shown in FIG.

(b) is a clock.

(c) is a reset signal.

(d) Adder cent register output Tt.

It shows.

As is clear from this figure, the successive addition result (average value) It is sent to the brightness corrector 11 at the next reset timing.

An example of the luminance corrector 11 is shown in FIG. In the brightness corrector 11, the average value It is written into another holding memory (RAM') 111 corresponding to the frame memory (RAM) 5 that stores the output of the brightness converter 4,
Retained.

Then, the conventional luminance-converted frame memory (RAM)
) When reading out the output data ■ of 5 and the average value It at that time for display on the display device (TV) 6, Ia >
Set thresholds Ia and Ib that are Ib, and if ■Ia > It > Ib, the correction value ■° is °0
゛.

■If It>Ia, the correction value I' is "negative" data.

■If Ib>It, the correction value I is correct data.

An appropriate correction (iI'' is made by the correction amount calculator 112 so that
and sends it to the adder (+) 113.

In the adder (+) 113, the frame memory (RA
The above correction value I' is added to the output data I of M) 5 and outputted to the display device (TV) 6 as display data.

Note that the correction amount calculator 112 uses [frame memory (RAM
) Output data ■ Ten average value It) is set as input address,
It may also be determined from a table stored in a read-only memory (ROM).

Thus, the frame memory (1?AM) according to the invention
In both the peak value method and the average value method, brightness correction for the output of It is distinctive in that it is performed on signals that have been converted into digital signals.

〔Effect of the invention〕

As explained above in detail, the brightness conversion circuit for Doppler display of the present invention measures the blood flow velocity of a living body by Doppler, converts the echo signal into a digital signal, and performs frequency analysis using an FFT analyzer. After determining the power spectrum of the echo signal, calculate the peak value or average value of the digital signal directly or after performing luminance conversion such as logarithmic conversion, and input the digital signal to the display device. Since the present invention is designed to correct the Doppler echo signal, it is possible to relatively easily and economically perform a Doppler display that matches the intensity of the Doppler echo signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing two embodiments of the present invention. FIG. 2 is a diagram showing the details of the peak detector 8 and its operation in the form of a time chart. FIG. 3 is a diagram explaining details of the brightness adjuster 9 and the concept of the adjustment amount I''. FIG. 4 is a diagram showing details of the average value calculator 10 and its operation in the form of a time chart. Figure 6 is a diagram explaining the principle of Doppler display. Figure 7 is a diagram explaining problems with conventional Doppler display. Figure 8 shows the problems. This is a block diagram showing the conventional technology for solving the problem. In the drawing, 1 is an ultrasonic probe. 2 is an analog/digital converter (A/D). 3 is an FFT analyzer, and 4 is a luminance. Converter. 5 is frame memory (RAM). 6 is display device (TV), 7 is automatic gain control unit (A
GC) 8 is a peak detector, 81 is a comparator. 82 is the maximum value cent register. 9 is a brightness adjuster, 91 is a holding memory (RAM'). 10 is an average value calculator. 101 is an addition value set register. 102 is an adder (+), 11 is a brightness corrector. 111 is a holding memory (RAM'). ). 112 is a correction amount calculator, 113 is an adder (+). P is a power spectrum data string. pmax is the maximum value of the power spectrum. Pi is the peak value of the power spectrum. ■ is a brightness conversion data string. It is brightness Average value of conversion data. I゛ indicates correction value or adjustment amount.

Claims (2)

[Claims] (1) An ultrasound diagnostic apparatus having a Doppler mode display function is characterized in that the power spectrum of the Doppler display is corrected and displayed so that the peak value of the brightness data indicating the power spectrum becomes the maximum brightness. Brightness correction circuit for Doppler display. (2) An ultrasound diagnostic apparatus having a Doppler mode display function is characterized in that the power spectrum of the Doppler display is corrected and displayed so that the average value of the brightness data indicating the power spectrum becomes a constant brightness. Brightness correction circuit for Doppler display.