JPS635481A - X-ray picture processor - Google Patents

Abstract

PURPOSE:To correct the edge blurring of a picture by executing a linear density conversion so as to divide the density of picture data at both side areas of the edge of an object into a positive and a negative and forming a spatial digital filter based on conversion density data. CONSTITUTION:The picture data collected by irradiating X rays on the object applying an edgeless response through an A/D converter 8 is stored in a data memory part 40 and supplied to an arithmetic processing part 55 provided with a density converting part 55. The linear density conversion is performed so as to divide the density in the picture data at both side areas of the edge of the object into the positive and the negative. A blurring correction filter forming part 60 forms the spatial digital filter based on the conversion density data in which the blurring in the edge part is corrected. The picture data thereafter is processed by such a filter and the blurring in the edge of the picture is corrected.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention corrects image blur based on image data obtained by irradiating and collecting X-rays on a subject that gives an edge response. The present invention relates to an X-ray image processing device having a function of creating a spatial digital filter.

(Prior Art) The causes of spatial blurring in X-ray images of objects used for medical diagnosis include the focal point size of the X-ray tube and the magnification of the object.・I)-In equipment using a TV system, 1-I, image carrier tube, etc. can also be a cause.

One way to find a spatial digital filter to correct the blur in this image is to apply XP to a subject that gives an edge response. A method is to create an ideal image based on the image data obtained by irradiating I, and then use the gradient method to find a blur repair filter using the sum of squares of the differences between each image data and the ideal image data as an index. Are known. A case in which, for example, a one-dimensional blur repair filter is obtained using this method will be briefly described below.

Let Bi,j be the density of the blurred image data, and let Ti,j be the density of the ideal image data created by an appropriate method.
It is assumed that the number of calculations is T, and the estimated repair filter at the time when the calculation is repeated T times is fk(T).

Here, i and J represent the addresses of each image data, and k represents the relative position of each filter coefficient of the estimated repair filter from the center filter coefficient.

Therefore, if the filter size is 2+1, -≦≦.

Then, the density of the image data obtained by applying the estimated restoration filter fk (sharpness) to the image data including the blur is Fi.

j (density of processed image data) is expressed by the following equation (1).

The ideal image data I i,j and the processed image data Fi,
The difference (difference image data) for each image data with jm is Ei,j
(T), this difference image data Ei,j(T) can be expressed by the following equation (2).

E i, j (T) = F i, j (season - 1i, j
...(2) Then, as an index (■) indicating the degree of similarity between the ideal image data I i,j and the processed image data Fi,j (T), the difference image data 2 in a certain region R including the edge of the subject is If a multiplicative sum is used, this index V can be expressed as the following (3).

Here, E i,j (season is divided by t;,j because normalization is taken into account.

If the gradient method is adopted as the image data convergence method, the estimated repair filter fk(D+1) at the next stage of the estimated repair filter fk(T) can be expressed by the following equation (4).

By substituting the above equations (1), (2), and (3) into equation (4), the following equation (5) is obtained.

(Margin below) ...(5) Here, a is the 7JO speed coefficient.

Therefore, it is possible to obtain a blur repair filter based on equation (5).

The density profiles corresponding to one line of the blurred image and the ideal image are shown in Fig. 6 (A>, (B)). The concentration profile corresponding to the line is shown in FIG. 6(C).

In the process of iterative calculation to obtain filter coefficients, the filter has the effect of changing the DC component of the image, but if the change in the DC component is large enough, the index V will not become small.

Therefore, the amount of change in the filter coefficients at each stage must be small.

Since the purpose is not to change the DC component but to approximate the shape of the edges, it is preferable that the DC component in region R be close to Q for this purpose.

(Problems to be Solved by the Invention) Therefore, in view of the above-mentioned shortcomings of the conventional device, the present invention creates a spatial digital filter without errors by removing DC components from image data used for creating a spatial digital filter. The object of the present invention is to provide an X-ray image processing device that can produce high-quality images without blur.

[Configuration of the Invention (Means for Solving Problems) The X-ray image processing device of the present invention emits X-rays to a subject that gives an edge response. Create a spatial digital filter to repair image blur based on the image data collected by the device, and apply the spatial digital filter to other image data collected by this device to obtain an image with the blur removed. In the line drawing@processing device, the image data of the area corresponding to both sides of the edge with respect to the image data used for creating the spatial digital filter! ! The present invention has a density conversion section that performs linear density conversion in which degrees are divided into positive and negative values, and the obtained density conversion data is used to create a spatial digital filter.

(effect) The operation of the image processing apparatus having the above configuration will be explained below.

First, this device irradiates X-rays onto a subject giving an edge response to obtain its image data, and the obtained image data is taken into a density conversion section to perform linear density conversion. As a result, image data of areas corresponding to both sides of the edge of the subject are separated into positive and negative regions, that is, temperature conversion data from which DC components are removed is obtained. This density conversion data is subjected to data processing to obtain a spatial digital filter for blur correction.

(Example) Examples of the present invention will be described in detail below.

The embodiment shown in FIG. 1 includes an X-ray tube 1 that emits X-rays toward a subject, and an X-ray aperture 2 that determines the X-ray irradiation field.
, an X-ray transmissive member 3 that supports an object and an X-ray shielding substance, which will be described later, an X-ray detector 7 that detects X-ray information of the object, and converts the output signal of the X-ray detector 7 into a digital signal. An A/D conversion section 8, a data storage section 40 that stores output data of this A/D conversion section 8, and this data storage section 4
Image data is taken in from 0 and a predetermined density conversion is performed, and the average value of the image density is calculated and linear calculations are performed.

an arithmetic processing unit 50 that performs various operations such as correction of scattered X-ray components and subtraction between multiple image data; and a blurring repair filter that takes in the processing results of the arithmetic processing unit 50 and performs blurring correction on the processing results. A blur correction filter creation section 60 that creates a blur correction filter, a D/A conversion section 27 that converts the output data of the blur correction filter creation section 60 into analog data, and a display means such as a CRT that captures and displays the analog data. 28, two arithmetic control sections including a CPtJ and controlling the entire device, and a bus 30 for transferring various data and control signals.

The data storage unit 40 includes first to sixth memories 9 to 14.
The output data of the A/D converter 8 is stored respectively.

The arithmetic processing unit 50 includes first to third arithmetic units 22 to 24.
and seventh to twelfth memories 15 to 20, of which the second calculation section 23 and the eighth memory 16 constitute a density conversion section 55.

The first arithmetic unit 22 is connected to the third to sixth memories 11 to
17!1, the average value of a specific density area of each image data is calculated, and the result is sent to the seventh memory 15.

The seventh memory 15 also stores in advance parameters necessary for calculations in the second calculation unit 23, such as coefficients (α, β) for one-dimensional scattered X-ray data correction.

The second calculation unit 23 extracts the coefficient (α
, β) and performs a linear operation represented by αx1+β on the input image data (this is referred to as [xi J), and stores the result in the eighth memory]6 or the first
The data is sent to the memory 20 of No. 2.

The third calculation unit 24 takes in the image data taken in from the first memory 9 or the second memory 10 and the image data taken in from the eighth memory 16 and subjected to linear calculation, and processes these images. A subtraction process is executed between the data and the result is stored in the ninth memory 17. Tenth memory 18. The data is sent to one of the eleventh memories 19.

The blur repair filter creation section 60 is configured to use the thirteenth memory 2.
1 and 4th. It is configured to include fifth calculation units 25 and 26. Then, the fourth calculation unit 25 takes in the image data from the twelfth memory 20, performs predetermined data processing on the image data, and performs blur correction 1! A filter is created, and the data of this blur repair filter is sent to the thirteenth memory 21 and stored therein. .

The fifth calculation unit 26 uses the blur correction filter data stored in the thirteenth memory 21 for the input image data that is taken in separately from the image data for creating the blur correction filter described above. A filter operation is executed and the result is sent to the D/A converter 27.

The D/A converter 27 converts the image data subjected to the filter operation into analog data and sends it to the display means 28.

Next, a subject including the X-ray transmitting member 3 will be explained.

The object to be photographed is a thin thin plate-shaped X-ray absorbing member 4 made of aluminum, copper, iron, etc., as shown in Figure 2 (A).
．． 5. An X-ray shielding member made of a thin thin plate of lead or the like to obtain scattered X-ray data in one-dimensional direction as shown in FIG. 2(B). In order to correct the scattered X-ray data as shown in FIG. 2(C), a small piece-shaped X-ray shielding member 6 that can obtain scattered X-ray data in a minute area is used.

Then, the X-ray absorbing member 4 and the X-ray shielding member 5.6 are placed on the X-ray transmitting member 3 in FIGS.
), (F) as shown in FIG.
0G, 70e.

70f and 70d.

Next, the operation of the apparatus having the above configuration will be explained.

First, each of the subjects 708 to 7 shown in FIGS. 3(A) to 3(F)
X-rays are irradiated from the X-ray tube 1 at each point 0f, and data of these X-ray images is collected.

The obtained X-ray image data of each of the subjects 70a to 70f is stored in the second memory 10. Fourth memory 12, sixth memory 14. First memory9. Third memory 11. The data is stored in the fifth memory 13.

Next, the first arithmetic unit 22 reads the X-ray image data of the subject 70f from the fifth memory 13 under the control of the arithmetic control unit 29 and addresses the The image data (this is referred to as "scattered X-ray component data f") is obtained, and the obtained image data and its address are sent to the seventh memory 15 and stored therein.

Furthermore, under the control of the calculation control unit 29, the first calculation unit 22 calculates the scattered X-ray component data C using the same procedure for the image data of the subject 70c stored in the sixth memory 14. The scattered X-ray component data C and its address are sent to the seventh memory 15 and stored therein.

Next, the first arithmetic unit 22 executes the process as shown in FIG. 3(E) stored in the third memory 11 under the control of the arithmetic control unit 29.
The image data of the subject 70e shown in FIG.
1 line of direction e.

-ei is selected, and the image data at the address closest to the addresses of the two X-ray shielding members 6, 6 in the scattered X-ray component data f in this line eO-el (this is referred to as "scattered X-ray data e ) are determined and sent to the seventh memory 15 to be stored therein.

Roughly speaking, the first calculation unit 22 also refers to the address of the scattered X-ray component data C for the image data of the subject 70b shown in FIG. 3(B) stored in the fourth memory 12. Obtain scattered X-ray component data b.

Now, regarding the image data stored in the third memory 11 and the fourth memory 12, the profiles of the image data of each line of eo-et and bo-bl in FIGS. 3(E) and 3(B) are shown. For example, it becomes as shown in FIG. 4 (A>, (B)).

In Fig. 4 (A>), Fo and Fl are two image data (X-ray intensity) of scattered X-ray component data f, and E2
, E3 are two image data (X
line strength).

Similarly, in FIG. 4(B), Go and C1 are two image data (X-ray intensity) of scattered X-ray component data C,
Bt and B2 are two image data (X-ray intensity) of scattered X-ray component data b.

As shown in Figure 4 (A>), Fo and Fl are E2
, E3, and as shown in FIG. 4(B), co,
C1 has larger values than Bt and B2, respectively.

This means that for the subject 70e shown in FIG. 3(E),
X measured at the point corresponding to E2 on eo-e1
Since the radiation shielding member 5 occupies a larger area within the X-ray irradiation field than the X-ray shielding member 6, the scattered X that should originally be measured
This is due to part of the line being cut.

Therefore, it is not appropriate to use the scattering x line component data for one line of eo-el as it is, and correction thereof is required.

Such correction is performed as follows.

Ratio between scattered X-ray component data f and scattered X-ray component data b,
That is, FO/E2 in FIGS. 4(A) and (B)
, Fl /E3. Go/B1. Calculate C1/B2, and calculate the average value of FO/E2 and F1/E3 (this is referred to as 1 correction coefficient E) and the average value of Co/B1 and C1/B2 (this is referred to as ``correction coefficient B''). .) and store these values in the seventh memory 15.

3 (E) stored in the third memory 11.
) The image data of the subject 70e shown in
, the above correction coefficient F is taken into the above α, and the above correction coefficient O is taken into the above β.
is given, linear density conversion is performed on the captured image data based on these values, and the result is stored in the eighth memory 16.

Next, the image data of the subject 70d shown in FIG. The image data is taken into the arithmetic unit 24 of No. 3, where a subtraction process is executed between both image data, and the result is stored in the ninth memory 17.

Similarly, the image data of the subject 70b shown in FIG. is given O@, linear density conversion is performed on the captured image data based on these values, and the result is stored in the eighth memory 1.
6.

Next, FIG. 3 (A>
The image data of the subject 70a shown in and the corrected one-line scattered X-ray component data stored in the eighth memory 16 are taken into the third calculation unit 24, and subtraction processing between both image data is executed here. and stores the result in the tenth memory 18.

By these series of operations, the subject 7 shown in FIG. 3(D) can be photographed.
The image data obtained by removing one line of scattered X-ray components from the image data of 0d and the image data obtained by removing one line of scattered X-ray components from the image data of the subject 70a shown in FIG. 9. 10th memory 17.18
is memorized.

Roughly speaking, the third arithmetic unit 24 is connected to the ninth memory 17 and the first
The image data stored in the 11th memory 18 is taken in, a subtraction process is performed between the two image data, and the result is stored in the 11th memory 19. By this operation, it is possible to eliminate the influence of the positional dependence of the sensitivity of the X-ray detector 3 on the image data.

By the way, among the image data stored in the eleventh memory 19, only the data corresponding to one line is valid. The profile of this effective one-line image data is shown in FIG. 5(A).

Furthermore, FIG. 1B shows a profile of image data corresponding to one effective line among the image data stored in the tenth memory 18.

When using a plurality of lines as image data for determining a blur correction filter, the X-ray shielding member 3 is moved spatially while the X-ray shielding members 5 and 6 and the X-ray absorbing member 4 are fixed. By converging the image data again using methods such as
Since another line of valid data can be obtained, this process can be repeated as many times as necessary to obtain multiple lines of valid image data. At this time, in collecting both meeting data for the second time and thereafter, there is no need to collect the image data of the subjects 70a and 70b shown in FIG. 3 (A>) and FIG. 3 (B).

Next, correction of the non-uniformity of the image 'a degree based on the fluctuation of the voltage applied to the X-ray tube 1 and the N flow will be explained.

Even if the X-ray tube conditions (voltage, current) are set the same, the subject is not necessarily exposed to a constant amount of X-rays due to fluctuations in the applied voltage and current, and as a result, the overall displayed image The HW level often becomes non-uniform, but this can be solved by using the first calculation unit 22 immediately after collecting the image data to detect a specific density region in which density variation between image data is considered not to occur. Among the image data detected first, a certain density based on one image is used as a standard, and a second calculation unit is applied to all the remaining image data so as to match this base Q''h-a degree. Correction can be made by executing density conversion in step 23.

Now, the image data with one or more valid lines is the first one.
When the information is stored in the memory 19 of No. 1, the next step is performed.

The first arithmetic unit 22 takes in the image data stored in the eleventh memory 19, and calculates R1 and R2 in FIG.
, R3, the image density is determined in areas where there is almost no change in density on both sides of the edge of the object.

That is, if the concentrations in the regions R1, R2, and R3 are respectively Dl, D2, and D3, then the concentration D1
, D3 and the average value of the density D2 are calculated.

Since the density D1 and the density D2 are almost equal, the density D1
The average value of and the density D2 may be taken as L.

Alternatively, a region including all the etches of the subject may be assumed, and the linear components within that region may be averaged.

Next, the second arithmetic unit 23 takes in the image data stored in the eleventh memory 19, and for this, α=1. β=
-L, density conversion data is obtained by subtracting the average value from each image data, and the result is stored in the twelfth memory 20. Among the image data stored in the twelfth memory 20, an effective one-line profile has positive and negative densities on both the upper and lower sides of the edge with the 0 level as the border, as shown in FIG. 5(C). Become.

That is, the density conversion data having the profile shown in FIG. 5(C) has a density level lowered by the average value from the blurred image data shown in FIG. 6(A>) described above.

Further, the density conversion data corresponding to the ideal image data shown in FIG. 6(B) is as shown in FIG. 5<D>. Note that the profile of the density conversion data of the difference image data shown in FIG. 6(C) is the same as that shown in FIG. 6(C) described above.

When performing this operation, the concentration D1. It is sufficient that D3 and the density D2 are positive or negative, and the value of the average value is not required to be very precise.

Through the operations described above, the density conversion data, which is a prerequisite for determining the blur correction filter, is stored in the twelfth memory 20.

Next, the operation for obtaining a blur repair filter will be explained.

The fourth calculation unit 25 takes in the density conversion data stored in the twelfth memory 20, performs predetermined calculation processing on the data as described above to create a blur repair filter, and as a result is sent to the thirteenth memory 21. At this time, since the density conversion data is used, the above (5)
It becomes possible to perform calculations based on formulas more quickly than in the case of conventional devices.

The data of the blur correction filter is stored in the thirteenth memory 21 under the control of the calculation control section 29.

The blurring repair filter obtained in this way is used for all image data collected by this device. That is, the target general image data and the blur correction filter are taken into the fifth calculation unit 26, where filter processing is executed, and the result is sent to the D/A conversion unit 27, where it is converted into an analog signal. After that, it is sent to the display means 28 and displayed. This makes it possible to obtain high-quality images without blur.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the invention.

For example, in the above embodiment, the X-ray absorbing member 4 was described as providing two edge responses, but it is also possible to provide a larger number of edge responses by using a plurality of X-ray absorbing members 4. Can be implemented.

Alternatively, one edge response may be provided. In this case, the width of the X-ray absorbing member 4 is widened so that the shadow of the subject due to X-ray exposure covers half of one side of the X-ray detector 3. You can achieve your goal.

Furthermore, although the case where two X-ray shielding members 6 are used has been described, one or three or more X-ray shielding members 6 may be used, and the scattered X-ray component data measured by one of the X-ray shielding members 6 may be This can be implemented by arranging the X-ray shielding members 6 at such intervals that they are hardly affected by the presence of the radiation shielding members 6.

Roughly speaking, we have explained that when multiple lines of image data are required, the collection of image data and its processing are repeated, but by increasing the memory for storing image data, it is possible to Collect image data of
Data processing may be executed after that.

In addition, in image data processing, there is also a memory (eighth memory 16) that stores image data including one line of scattered X-ray component data that has undergone density correction, and one effective line from which scattered X-ray components have been removed. A large number of memories (9th memory 17, 10th memory 18) etc. are prepared to store image data including , and all the image data to be processed at each stage is processed before proceeding to the next stage. It can also happen.

In addition, the eighth memory 16 to the tenth memory 18
Since the valid part of the image data is for one line, it is also possible to replace it with a memory having a storage section (2) for one line. If multiple lines of image data are not required as a result, the eleventh memory 19. The same applies to the twelfth memory 20.

[Effects of the Invention] According to the present invention described in detail above, by providing a density conversion unit that performs density conversion on image data, spatial digital data is created using density conversion data from which the influence of DC components has been removed. It becomes possible to create a filter, and it is possible to provide a double-view processing device that is uniquely capable of providing high-quality images without blur.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example device of the present invention, and Fig. 2 (A>, (B), and (C) respectively show an X-ray absorbing member and an X-ray shielding member constituting a subject used in the same device. A perspective view, Figures 3 (A) to (F) are plan views showing the configuration of the subject in the same device, and Figure 4 (A> is Figure 3 (E)).
Figure 4 (B) is the X-ray intensity profile determined from the subject shown in Figure 3 (B), and Figures 5 (A) and (B) are the X-ray intensity profile determined from the subject shown in Figure 3 (B). The density profile of the image data sent to the density conversion section, FIG. 5(C) is the density profile of the density conversion data created by the density conversion section of the same device, and FIG. 5(D) is the density profile of the density conversion data created by the density conversion section of the same device. FIG. 6 (A) is the density profile of the density conversion data for the created ideal image data; FIG. 6 (B) is the density profile of the blurred image data used in the conventional device; FIG. 6 (B) is the density profile of the ideal image data used in the conventional device. The profile, FIG. 6(C) is the density profile of the difference image data of both the image skeleton data shown in FIGS. 6(A) and (B). 28... Display means, 40... Data storage unit, 50・
... Arithmetic processing section, 55 ... Density conversion section, 60 ... Blur repair filter creation section. (A) (B) Funeral diagram 2 (A) (B) (C) Figure 6

Claims (1)

[Claims] A spatial digital filter that restores image blur is created based on image data collected by irradiating X-rays onto a subject that gives an edge response, and the spatial digital filter is applied to other image data collected by this device. In an X-ray image processing device that obtains an image from which blur has been removed, the temperature of the image data in the area corresponding to both sides of the edge is divided into positive and negative values with respect to the image data used for creating the spatial digital filter. An X-ray image processing device comprising a density conversion unit that performs conversion, and uses density conversion data obtained by the density conversion unit to create a spatial digital filter.