JPS60207041A - Radiation tomography examination apparatus - Google Patents

Abstract

PURPOSE:To remove the noise component in an image without a large amount of memories and without imparing image quality and processing time, by judging a picture element having the different value from the value of a picture element, which is adjacent to a picture element noted in a reconstructed image, as the noise. CONSTITUTION:Data from a memory 8 undergoes preprocessing by a preprocessor 15 of a high speed operating device 9 and then undergoes convolution by a convolver 16. Thereafter, the result is reversely projected on an image memory 18 by a reverse projector 17 and an image is reconstructed. The noise component is removed from the data of the recondtructed image by a noise remover 19. Its function is as follows: the value of the picture element at each picture element position in the reconstructed image is compared with the value of each picture element in a predetermined area around said picture element; the value of the picture element is intactly adopted when the different is smaller than the predetermined threshold value; and the average value of the values of the picture elements in the comparing areas is used as the value of said picture element when the picture element, whose value is smaller than the threshold value, is not present.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Insertion of the Invention) The present invention utilizes construction lines to obtain an image of a cross section of an object to be inspected by 1q(
This is J, the inspection of the object to be inspected.

[The aim of the technique of invention is to create internal defects in objects, etc., in a non-destructive manner.

1 piece of equipment that can measure the durability well
There is an radial fault inspection device called C-1 (abbreviated as C-1).

This device can be used as an analogy (as a direct emission copper ray source, which spreads out in a 5P fan shape), an X-ray beam that covers the X-rays, and a 2:1 beam to this commercial radiation source via the object to be inspected. Arrange the copper wires facing each other and place them facing each other in the direction of the spread of X-rays. For example, source and detector in the same direction.

X-ray absorption data from multiple directions of the surface to be inspected (Alli) was collected while rotating sequentially at 1800 to 3600). The image of the IIi layer is formed on each section of the tomographic plane.
J also D gradation C image reconstruction C monkey σ), tomographic IIJi
It is possible to know (・kiru,.

This is called the 31! vessel.

Set C-+, move this X-ray source and detector along the cross-sectional edge of the object to be inspected from 1 to Lahasskin 1, and at the end of the 11-Tubers scan, rotate at a predetermined angle at γ10,000, rotate C+Tj and 1
~ Lovers 4- Yang? Uh, the so-called 1111th generation,
Pencil Him
and test jJ1. Using a detector with a large number of elements (P)
It is also called an improved version of the 1111th generation, so-called 21st+, which has 7p-)(
CT 2 :, l(・)
There is.

However, in general, there is always a noise component in the obtained image (,1).And, by using these box height lJ X-ray scans, the obtained reconstructed image has (J When looking at the image of a defect, there is a possibility that it may be distorted, overlooked, or mistaken for a defect, so it is necessary to remove noise components from these images.

Various studies have been conducted in the past regarding the removal of noise components contained in this image. The representative ones are:
Averaging of 18 components by a low-pass filter and image Φ combination for high-frequency filtering and removal. On the other hand, the correction using []] Corvus Noil results in the abrupt change in the spatial frequency of the image actually being distorted, making it impossible to obtain a reliable tomographic image. In addition, multiple images are required including Φ, and devices that handle digital data such as CT scanners require a huge amount of memory to store image data, and data collection is difficult. A lot of time is spent on overlay processing.

Therefore, without compromising image quality or processing time.

It also requires a huge amount of memory! It would be desirable to have a fj'i IA line pgI layer inspection device that can remove noise components included in images without any noise.

1 of the Invention 1 In view of the circumstances of 1 and 1j, the present invention has been devised to improve the image quality without impairing the C11 image quality processing and without requiring a huge amount of memory. It is an object of the present invention to provide an fj9.lIJ wire breakage sound inspection device capable of removing noise components contained therein.

[Summary of the Invention] In order to achieve the distribution method, the present invention is directed to a specific cross-section of an object to be inspected, in which the radiation transmitted through the specific cross-section is irradiated from each direction. In the apparatus, the amount of radiographic radiation is collected as one data, and the collected radiographic data is subjected to image reconstruction processing to obtain a reconstructed image of a specific cross section of the object to be examined. , if there is a smaller pixel at each pixel position in the reconstructed image, the number of the pixel is used as the value of the pixel, and if there is no smaller pixel than the threshold value, the pixel is compared. A means for replacing the average height of the pixels of the region with the ratio of the pixel is constructed together, and the C'I image is X-ray focused and phosphorus 51 rubits.

The spatial frequency of the image is limited by interpolation.
5 of a certain frequency vlLll cannot appear C゛.

Also, the sharp changes in the reconstructed image (below the system frequency limit) are considered to be a sign of re-creation. For the pixel at the position (predetermined 11.
Compare the values of each pixel in the comparison area.

If the difference 1 is smaller than the 1st threshold value, the value of the selected pixel is used as the value of the pixel, and write 1.
For ribs that do not have anything smaller than the image, the average grain of the pixel in the comparison area of the pixel is changed to the value of the pixel by Cβ, without degrading the image quality or processing time, and without requiring a huge amount of 4J memory. The noise components included in the image can be removed without causing any damage.

[Embodiments of the Invention] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows the structure of Kimonao's ribs [This is a cock diagram, and here C is an example of the 2111th generation C [Sukigo・)] (Explanation is reversed. In the figure, 1 is narrow) 7, an X-ray tube for emitting -IXX-rays XR, and 3 a radiation detector e disposed opposite to the Xta tube 1. 1 This detector 3 is 7 no 7: nobby
1. In the direction of spread of X-rays 2 is an imaging area C, and this imaging area 2 is provided with a daple (not shown) that holds the object to be inspected. The direction of the arrow 5 is +-]-j i1~ so that it can be avoided. There is a configuration in which X-ray absorption filters from various directions can be collected for a predetermined cross section of the body.

In this embodiment, the detector 3 has an 8-tunnel 'C-.

Rotate the rotation in 6''increments'C- (if you take uhb).

1 Suki [Shinr-240 Prosiction, 1 Noroshi 1
480 points of data were collected per action.

In short, Databi 2 Sochi is 05#C-. In addition, the required X-ray beam size per radiation detection element is 3m.
There is X3m'r.

6 integrates the detection current corresponding to the required radiation intensity output from the detector 1 for each X-ray exposure, converts it to Δ/D (7] 1 Cogu Digitano 1.), and converts it to complete γ. If so, it is a data collection system that interrupts the central processing unit 7. The central processing unit 7 reads the data from the data collection device 6, stores it in the memory 8, and uses this j' data.
C part:
This function controls the flow of data up to reconstruction using back projection.

In addition, the memory 8 plays the role of main memory as a temporary storage location for the control program of the central processing unit 7 and the X-ray absorption data obtained by the X-ray projection that can be transferred to the data acquisition device 6. .9 is pre-processing for X-ray absorption, in addition to pre-processing for linear radiation fluctuations, processing for beam hardening, etc., and performing correction W.
'This prequel L'l' Performance data Q; J L (]
There is a high-speed arithmetic unit C that performs symbol symbol, back no. 1o is a fixed disk device for storing a large number of images, X-ray absorption data, etc. reconstructed by this high-speed calculation device 9;
11, and 1 a system L including a display device for displaying an image etc. reconstructed by the high-speed calculation equipment 9 and also controlling the system;
There is a console C. 12 is a low-speed pass line for detecting system commands and device status, and 13 is a high-speed Cy
There is a high-speed pass line C for the flow layer. .

Next, details of the high-speed arithmetic unit 9 including the Il and M removal functions according to the present invention will be explained with reference to FIG. 2. In the figure, 1/l is a control section; In addition to controlling the flow of data within the system,
It has a function to set parameters for the 1i Riru Eichō removal equipment. 15 is a preprocessing device, and this preprocessing device 15 sequentially performs dose hardening correction on the X-ray absorption data sent from the control unit 14, and also performs processing such as OG<logarithm) conversion. conduct. 16 is a convolver C, and this convolver 6 saves the data (projection pig) processed by the preprocessing device 15 and stores the filter function and convolution result to the back projection device 17. The back projection device 17 directs this data in the 1-image memory 18 in the angular direction based on the angular information f=J l-1 (). (Since the image is reconstructed using back projection,
be. Ma] Hey, 19 is! [There is a sound removal function C that removes chords in the reconstructed image obtained in the 1st image menu 18F based on the setting parameters from the 1st stroke side. 2Q is the terminal 1 in the high-speed arithmetic unit 9, and 21 is the data bus.

Next, the operation of this device having the configuration described in 1- will be explained.

First, place the object to be inspected on a table (not shown).
Next, generate X-ray XR from the X-ray tube. Then, the X-rays XR pass through the object to be inspected and reach a detector 3 arranged opposite to the X-ray tube 1. Then, each detection element of this detector 2 outputs an electric low mowing signal corresponding to the strength of the required teaching line. 1. To this electrician. The data collection device 6 manually integrates this electrical signal for each C1 detection channel, and converts it into digital data through A/D conversion. '1, the data collection device 6 interrupts the medium-heat calculation device 7M, and thereby the medium-fire calculation device 7 stores this gas data in the mail 8. Next, the medium-fire calculation device 7 gives a command to the Chidal 1 drive device (not shown) to move the t-pull at a predetermined pitch.
Nzuru. Then, the movement as mentioned above (11 is (+I).

Data collection is 4! (Yuri,, Ishi + (, 1 to Lovers in the predetermined range ↓ When the yang is finished, the [1-Dage 1-n of the predetermined angle (in this case, the pitch of 8 melons) is 1 to rubber sequence 1:11 is completed and C data is collected.

In this way, in the range of 380'')ρ)(i゛-
When the data collection is completed, the medium-heat calculation device 7 then uses this memory 8.
The data stored in the C is read out and sent to the high-speed arithmetic unit 9, which is then received by the high-speed processing unit 9, which performs preprocessing on the retrieved data.

Then, after filling in the prefix, the image was reconstructed by back-projecting the data that had been created, and the image was reconstructed. The chord component of f:l is removed.This image is reconstructed in a fixed manner and is stored in the fixed image display unit 10, and also displayed on the system console 11 (its image display device). (12 or more displayed in 2) is a general operation explanation of this device.

Next, the main parts of the apparatus of the present invention will be explained.

)Mere-(The incoming data is pre-processed by the pre-processing device 15 of the high-speed arithmetic unit 9, and then convolved with the image data by the image memory 181 by the projector 17.) projected (reconstituted 3, then C
1. Does the box height removal device 1C,) remove chord components from this reconstructed image data? UU.

This carp sound component is removed as follows: C7 Uu.

However, the present invention has (1) a CT image with X-ray focus rise, inter-detector roll rise,
Linnor pip, interpolation, J, -) is limited to one frequency, and a certain frequency cannot reproduce 1 quintillion images.

(2) Reconstructed image ζ, cis''7j, a sharp change exceeding the frequency limit is considered to be a chord of re-H6 formation.

It is based on the dream called "Mom", and theoretically, from the Book of L, there is a method that calculates the local frequency and eliminates the power by that restriction, but in reality, it is not worth paying attention to. If the value of a pixel is significantly different from the value of a pixel adjacent to the pixel, it is considered to be noise. The plant used for the first judgment is determined depending on the system and the subject to be examined.

The first effect will be explained below.

Now, let us consider an object to be inspected, which is a circular + J-shaped object with a plurality of large and small holes drilled along the axis of the object, as shown in Fig. 3. When the image profile is taken along a line passing through the center of the name tag of this object to be inspected, the profile, which should actually look like a dotted line, is distorted as shown by the solid line in FIG.

Then, it can be seen that the difference in the reconstructed data C/C T' (iffl) that affects the LJ and X-ray absorption coefficient becomes smaller for a hole with a small diameter.For example, f is 241IJ at level A.
If you transform, you can only see the 5th hole, but if you lower the level from B to C, you can see the 0.5 Anchor 1 hole. However, in reality, as shown in Figure 5, there is noise, so if you lower the level, the noise will also be recognized as a hole. In this way, noise areas in an image may be obvious by looking at the profile.

Further, since noise is usually a high frequency component, the noise part shows a more rapid change. Therefore, a limit of rapid changes will be used to identify the ode & iE standard signal, and that limit is determined by the above-mentioned clause fj(t). In actual case, the value M is set to 0 between adjacent pixels.
You can see that it only changes by a minute. , Noko I Doshi, C
The detection depends on the set of trl gs in the system, so sufficient knowledge is required and at the same time it can be determined empirically. FIG. 6 shows a comparison area when focusing on pixel IM (3, 3). This comparison area is here C? 'The pixels of both adjacent cars of JII Ryoju are 8 pixels, and j5 is a diagonal line (horizontal line). l-”C
Yes 3, Rimuwa 15. For example, if the number of pixels in the actual reconstructed image increases to 240x240, the first pixel (J) of this pixel, and the "N11" pixel are centered in order, and the data of this pixel and the data of this pixel are placed in the comparison area around this fourth pixel. Calculate the difference between each pixel of the pixels and use The average of (iQ) of the pixels in the comparison area (ii: j is > iF pixel (1) Ki Toshi (
1, which is 17), J is selectively applied to process 1 in Fig. 7, and low bass fill is applied! Various effects 1
', 1 line. .

As a result, the detection ability and processing of the C1 image +1. 'l listen to 4
Without being a member, there is also a 1J Yu person's mail [Rira Necessary and J t
J” is a forceps held in the image?) component removed IC-Saru J
, Unanu.

The present invention is described in 1-1 and is not limited to the embodiments shown in the drawings, but may be modified within the scope 111 (and may be carried out in an appropriate form). There is.

For example, in the above Example C, second generation X-ray 01 is used as Example Lm and -
) (I will explain this, but I can apply it to other /j expressions and transform each of them), and can also apply to other general 'eh I'''I images. (From the knowledge of the monk removal (gotsui), system 11, the threshold 110M
If you decide r knee, there is use 111 function C, ma]ko, -1
- In the case of the eight-point embodiment, the comparison area L is 8 adjacent points of 11 pixels and 1. However, as shown in FIG. 8, four points touching 11g of A centering on J, ox 2d, both fF, 1-)1< are drawn so as to take the pixel RC of the comparison area.

In addition, in the present invention, if there is a difference between the pixel at the comparison point and the pixel in the comparison area A, and there is a difference smaller than the threshold M, the average of 410 of the 8 pixels in the comparison area. (i+: + is the pixel of the second point (1θ, but as shown in Figure 9, 3111 pixel 1) [centered at 1
) 8 pieces (for example, 2 /lOX 2401iji+
(7) J using ψ average 110 may also be used.

[Effect of the invention] As described above, the present invention has the advantage that λ
・Collect the 40 rays that pass through the specific front surface from each of the devices and each of them as radiation QA ray transmission data, and add the radiation transmission data to this collected The device performs image reconstruction processing to obtain a reconstructed image of a specific cross section of the object combination: At 1°1, each pixel of the C1 corner image (11ii@ image, +, 1 and 2 Compare each stroke in the comparison area 1 with 11- of +3, and the difference between each of them is 4ji, which is smaller than Koshikii-e. If there is, the corresponding pixel's (
Set C6 as the base of the pixel; 1. The threshold (less than IQ is 'fF IjL/ /, 't aid, 1
This image is equipped with a means for replacing C with the average value of 1ifj of the pixels in the comparison area of +□ as 11C of the pixel, and the C1 image is
(The spatial frequency of the elephant is limited, and at a certain frequency
The fact that the internal regulations cannot be established, and the mountain composition image e system j
Based on the fact that a sharp change exceeding the frequency limit is considered to be 41 tones at the time of composing the image (using an appropriately set shisai tone, it is possible to Compare the value of each pixel in the defined comparison area, and if there is a value smaller than the threshold value, set the edge of the pixel as it is to 110, and - , I+='1, where there is no smaller value, means that the average value of the pixel values of the 11 branches of the comparison of the pixel is replaced with
In order to eliminate the rooster component contained in the image without wasting time or requiring a large amount of memory, we have developed an IP 1-ray tomography inspection system that takes into account the features of the image. There are things you can offer.

[Brief explanation of the drawing]

FIG. 1 shows the schematic configuration of the device of the present invention, and FIG.
Fig. 2 is a four-dimensional diagram showing the main structure of the present invention, Fig. 3 is a sectional view of an example of a test object, Fig. 4 is an example of a protease of the image, Fig. 1, and Fig. 5 are images. An example of a signal and a chord signal is shown in FIG. -1~, 8th period,
FIG. 9 is a diagram showing another example of the pixel of interest and the comparison area. 1...XvA! Tube, 3...Radiation detector, 6...Data collection device, 7...Central communication device 8...Memory, 9...High-speed i-hanging device, 10...Human store record 1 meaning・
equipment, 11...] system, 12...manpower output,
14...High-speed display device'2 controller, 15...
Pre-processing device, 16... product-sum device (two-litter), 1
7...Back projection device, 18...Imeshinushiri (music color scheme 1.1), 1≦)...! Fl? O1i removal device. Applicant's agent

Claims (1)

[Claims] One section of the apricot to be tested is placed in a fixed cross section of each section.
The line h3 is collected as the transmitted radiation data, and the collected radiation data is subjected to the image ↓1 composition processing. 1,
In the apparatus designed to obtain both constituent images of the '11 cross section (
, ijj 101c mountain ring formation masterpiece? ? , (For both cars at 3' / position (when the surroundings are planned, the pixel of the pixel is left as it is, and the image is set at !'8. 11. 31 The pixel in the comparison area of the pixel is 11
``1'' is the setting for the pixel, (1 is equipped with a means for placing the pixel, 1, 'west attack/1 (QiJ line tomographic detection f1 device.