JP2006038521A - Method of correcting magnification in radiographic examination digital image, and method of evaluating defect therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an index capable of judging an outline dimension of a defect at one glance, in digitalization. <P>SOLUTION: In a radiographic examination using a digital image acquired by irradiating a transmittance meter for the radiographic examination and an examining object with a radiation, by sensitizing a film with the radiation transmitted through the transmittance meter for the radiographic examination and the examining object (procedure 64), and by scanning the film with a scanner, for determining a radiographic examination result, a resolution confirmation chart is scanned together with the film as the same image data (procedure 68) when scanning the film, an image magnification when observing the digital image is determined from a line pair image by a plurality of line pair charts comprising different in dimensions printed on the resolution confirmation chart (procedure 76), and an image by a scale worked in four sides of the resolution confirmation chart is also observed on the digital image together with the examined object, to evaluate the outline dimension of the defect (procedure 78). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radiation transmission test apparatus used for a transmission test using radiation, and a method for correcting a magnification of a radiation transmission test image, wherein the magnification is corrected at the time of observing a digital image of an inspection film obtained by imaging a specimen in a radiation transmission test. The present invention also relates to a defect evaluation method capable of determining at a glance the approximate dimensions of defects present in a radiation transmission test object.

  At present, in the radiation transmission test (hereinafter also referred to as RT), the inspection film obtained by photographing the test body with the radiation transmission test apparatus is visually judged by the inspector, and the presence or absence of the defect of the test body copied in the inspection film. (Hereinafter referred to as a film method), and a method for directly acquiring a digital image of a radiation transmission test image and confirming the presence or absence of defects on the test specimen on the digital image (hereinafter referred to as a filmless method) It has been. In recent years, a radiation transmission test film is scanned using a digitizing apparatus to obtain digital image data, and the image data acquired here is observed to determine the presence or absence of a defect in the specimen (hereinafter referred to as “defects”). (Semi-filmless method) may be performed.

  In the radiation transmission test, it is the most important point from the viewpoint of ensuring the quality of the radiation transmission test to confirm that the resolution of the acquired film image or digital image is sufficient to detect defects. However, the index for judging this is the transmission meter for radiation transmission test. When the specimen is photographed, the transparency meter for radiation transmission test is simultaneously copied in the inspection film and image, and its appearance is visible. This clarity is used as an index for evaluating the resolution of film and digital images.

  The general permeability meter for radiation transmission test used in the above test is standardized by JIS Z 2306-2000 “Transmission meter for radiation transmission test”. There are two types of permeation meters. The wire-type permeability meter is further classified into two types, a general type and a band type. The general wire-type transmissometer has a structure in which seven wires having different diameters are embedded in a plastic or the like with little X-ray absorption. The band-shaped wire permeability meter has a structure in which nine wires of the same diameter are embedded, and is mainly used for photographing a circumferential welded portion of a pipe. On the other hand, there are two types of perforated penetrometers: square and circular. The square and circular plates have a thickness corresponding to 2% of the thickness of the discriminating specimen, and on the plate, It is a shape with a through hole with a dimension related to the plate thickness, such as a circular hole having a diameter equivalent to the thickness, a circular hole having a diameter that is half the plate thickness, or a circular hole having a diameter twice the plate thickness. .

  For example, in the case of steel, these transmissometers for radiation transmission test are as follows, as shown in JIS Z 3104-1995 “Radiation transmission test method for steel welded joints”. It is required to be able to clearly identify the lines and holes in the inspection film by imprinting an image of a wire or a circular hole in the inspection film. Also, in recent years, for the quasi-filmless radiation transmission test, when acquiring and confirming the radiation transmission test result as a digital image, the transmission used for film shooting is used to quantitatively evaluate the resolution of the acquired image. The shape of a multimeter with a rectangular slit through-hole having a slit width equal to, twice, or four times the slit thickness of the penetrometer and a slit interval having the same width as the slit width. The transmission meter for radiation transmission test (referred to as a line pair type transmission meter) is used. Then, at the time of film photographing of the radiation transmission test, the radiation transmission test permeability meter is copied together with a test body into an inspection film, and then the inspection film is scanned with a scanner to obtain digital image data, and the digital image data Based on the above, the MTF values relating to the light and darkness arranged in the slit width direction of the image of the transmissometer for radiation transmission test are obtained, the resolution of the image in the inspection film is quantified, and the digital image data relating to the inspection film is obtained. A method of acquiring and storing in an electronic storage device has also been proposed, and the use of a transmissometer having a shape different from that of a conventional wire shape or perforated shape is being advanced.

  Further, in the quasi-filmless RT, when a photographed inspection film is converted into a digital image by the digitizing device in the conventional RT film digitizing resolving power confirmation method and film digitizing device, the resolving power having a plurality of line pairs is used. By digitizing with a confirmation chart (also called a line pair type resolution confirmation chart), the line width and pitch width of the line pair captured in the film image are measured, and the deviation of the line width and pitch width of the resolution confirmation chart is allowed. A method that can quantitatively guarantee the resolution of digital image data by comparing with (see, for example, Patent Document 1) is proposed.

  In the radiation transmission test using a digital image by the above method, a judgment index for guaranteeing that the resolution of the acquired image is equivalent to visual observation by using a line pair type transmissometer and a line pair type resolution confirmation chart. Has been established.

In addition, as a method for determining the defect size of a radiation transmission test specimen, in the conventional film system, a rough ruler is directly applied to a portion where a defect image is confirmed during film observation, and an approximate size has been evaluated. However, when an image is enlarged or reduced on a digital image, a complicated procedure such as calculating by multiplying the measurement result by the enlargement or reduction magnification is required when directly measuring with a ruler. As one of the methods for solving this, a scale is processed by slit processing on one side of a rectangular plate material of a perforated permeability meter for a radiation transmission test, and a specimen is observed in the image when observed on a digital image. There has been proposed a method in which a scale is captured together with an image and an approximate defect size is evaluated on a digital image (see, for example, Patent Document 2).
JP 2003-209654 A JP 7-218240 A

  When observing a radiographic test digital image acquired by the above-mentioned method and having a guaranteed resolution on a computer display, a clear index for determining how much magnification is appropriate to observe is currently clarified. Not. Therefore, there is a possibility that the visual observation conditions vary depending on the person observing the image, and the inspection determination result is affected.

  In addition, regarding the sizing of defects when a defect is found in the image by observing a digital image, as described above, in the conventional film-type radiation transmission test, the ruler is adjusted to the defect detection site in the film. The rough dimensions of the defect could be determined instantly.

  However, in a radiation transmission test using a digital image, when magnifying and observing the image, or when observing the image by changing its size on the display, the above ruler is applied to the display. Thus, it is necessary to divide the dimensions obtained by the predetermined magnification of the image, and it is very difficult to determine the defect dimensions instantaneously.

  On the other hand, with regard to defect sizing, the method of processing and using a scale slit in the above-mentioned transmissometer may vary the density of the scale image depending on the thickness of the transmissometer, making it difficult to see the scale as an index for defect dimension evaluation. There is sex. In particular, in a quasi-filmless radiation transmission test in which a film is digitized to obtain a digital image, this becomes prominent if a film having a high density is digitized.

  The present invention has been made in view of the actual situation of the prior art as described above. The purpose of the present invention is to observe an image by scanning an inspection film photographed in a radioactive transmission test, or to directly digitally convert a radiation transmission test result. An object of the present invention is to provide an index that can keep the magnification of an image constant when observing the image.

  Another purpose is to record on a film, and simultaneously read and digitize the film image and the reference film. In other words, in a quasi-filmless radiation transmission test, what conditions are used when sizing defects on digital data? It is another object of the present invention to provide an index that allows the defect size to be estimated or recognized instantly even when the specimen is photographed.

In order to achieve the above object, the present invention is directed to a radiation transmission test apparatus used for a transmission test using radiation, wherein a radiation meter for a radiation transmission test and a test body are irradiated with radiation, and the transmittance for the radiation transmission test is measured. The image on the image recording medium of a plurality of slits provided in the transmissometer for radiation transmission test, which is exposed to the radiation transmitted through the meter and the test body, is converted into digital image data and converted into the digital image data. And a control means for setting an enlargement magnification suitable for observing an image on the image recording medium using the line pair image as an index. The specimen was irradiated with radiation, an image was recorded on the image recording medium with the radiation penetrometer for radiation transmission test and the radiation transmitted through the specimen, and recorded on the image recording medium. Using a line pair image formed by a plurality of slits processed in the transmissometer for radiation transmission test as an index, an enlargement magnification suitable for observing the image recorded on the image recording medium is determined, and the radiation transmission test image is enlarged. It is characterized by correcting the magnification.

  Further, the present invention irradiates a radiation meter for a transmission test and a test body with radiation, sensitizes the film with the radiation transmitted through the transmission meter for the transmission test and the test body, and scans the film with a scanner. In this case, the resolution confirmation chart is read together with the film as the same image data, digitized into digital image data, and the approximate defect size of the test object is determined from the scale image based on the resolution confirmation chart.

  More specifically, the digital image of the radiation transmission test is used as a transmission meter for the radiation transmission test, and the slit through-holes processed in the transmission meter for the radiation transmission test are each equal to the plate thickness, half or double. Various types of transmissometers for radiation transmission tests having three types of dimensions of 4 times and 8 times, and having a plurality of pairs of slit intervals having the same width as each of the slit widths. Line pair type transmissometers) are photographed simultaneously, and multiple pairs of line pairs are imprinted in the digital image that is the test result. However, the image of the line and space of the line pair smaller than the line pair of the above dimensions can be inspected by enlarging the digital image according to conditions that are difficult to confirm by visual inspection. So as to correct the magnification of the radiographic examination film image by using a constant.

  In addition, in the quasi-filmless type radiation transmission test, when the captured film is converted into digital data, as a resolution confirmation chart that guarantees the resolution of the acquired image by simultaneously capturing it in the image, a rectangular line, the line width, A line pair of a shape having a plurality of pairs with the same width interval as a pair, using a resolution confirmation chart printed with a plurality of different dimensions, among the line pairs displayed on the acquired image, three lines having different dimensions For a pair, the maximum dimension line pair and the middle dimension line pair can be confirmed by disassembling (separating) as different filaments, but only the smallest dimension line pair cannot be confirmed by disassembling (separating) The image enlargement magnification is adjusted and observed, and the image enlargement magnification is corrected.

  Furthermore, during the quasi-filmless radiation transmission test, the resolution check is performed by printing the millimeter scale on the two sides and the inch scale on the other two sides of the four sides of the rectangular film on the resolution confirmation chart. When digitizing a film using a chart, a scale image is imprinted in the digital image obtained by digitalizing the film at the same time as the film. To be evaluated.

  In the embodiment described later, the computer 61 corresponds to the control means, the scanner 60 corresponds to the reading means, the display 62 corresponds to the display means, and various processes are performed by a CPU (not shown) provided in the computer 61. The program is executed using a RAM (not shown) as a work area according to a program stored in a ROM (not shown). The program is loaded from a recording medium (not shown) or loaded from a server via a network (not shown).

  According to the present invention, it is possible to obtain an index that makes the magnification level constant during image observation when correcting the magnification of a digital image in a radiation transmission test. In addition, when observing an image in a quasi-filmless radiation transmission test, in which an inspection film taken in a radiation transmission test is converted into digital data, it is possible to provide a scale image that serves as a standard for evaluating defect dimensions in the digital data. . Further, when scanning the film with a scanner, the resolution confirmation chart is read together with the film as the same image data, and digitized into digital image data. Therefore, the approximate defect dimensions of the test object based on the scale image of the resolution confirmation chart Can be determined.

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

  In this embodiment, as a transmission meter for a radiation transmission test used at the time of filming for a radiation transmission test, the slit through holes processed in the transmission meter for the radiation transmission test are each equal to the thickness T, Has three types of dimensions: half, double, quadruple and eightfold. In addition, a variety of transmission meters for radiation transmission tests having a plurality of pairs of slits having the same width as each of the slits are used, and a line formed by the slits and the slits in the inspection film during radiation transmission. Photograph the pair and the specimen at the same time. And after digitizing the photographed inspection film, the minimum line pair image cannot be distinguished for the light and dark line pair images by the slit pairs of the three types of dimensions in the inspection film image, but the intermediate and maximum dimension The line pair images are standardized by correcting the magnification at the time of image observation under conditions that can be clearly distinguished by visual observation, and image data is stored and acquired under these conditions. At that time, a filmless inspection method capable of directly acquiring a radiation film image as digital data may be used.

  As the filmless system, for example, a system called digital radiography is generally adopted. Digital radiography includes systems such as computed radiography (CR), film digitizing, or flat panel image sensor (FPD). Computed radiography (CR) uses an imaging plate (IP) coated with an illuminant that exhibits a photostimulable luminescence phenomenon to store the amount of irradiated radiation, and then scans the surface of the imaging plate with a laser beam. Thus, light emission from the stimulable substance is promoted and the light is read. Film digitizing is a system that digitizes a photographic image of a film scanned by a dedicated film scanner. Flat panel image sensors have millions of photodiode elements (pixels) on an amorphous silicon or amorphous selenium substrate, and each element stores a charge proportional to the radiation dose or more. The radiographic image can be displayed on the CRT in real time by directly transferring the charge amount as a density value to the computer.

<First Embodiment>
FIG. 1 is a front view of a transmissometer 100 for radiation transmission test according to the first embodiment of the present invention. Specifically, as shown in FIG. 1, a transmission meter 100 for radiation transmission test used in a radiation transmission test is formed on a rectangular plate material 1 having a plate thickness T of 2% of the thickness of a test body. Equal (T), 0.5 times the plate thickness (0.5T), 2 times the plate thickness (2T), 4 times the plate thickness (4T) and 8 times the plate thickness (8T) Various types of transmission meters for radiation transmission tests (hereinafter referred to as line pair type transmission meters), which are slit-formed and have a plurality of pairs of slit intervals S each having the same width as each slit width W. Call). In FIG. 1, a slit 2 having a width W equal to the plate thickness T, a slit 4 having a width 2W, a slit 4 having a width 4W, a slit 6 having a width 4W, and the slit intervals S, 2S, 4S (3, 5, 7). 2 shows an example of a permeability meter in which a plurality of pairs are processed.

  This is because the conventional line pair type overmeter has through-holes 2, 4, and 6 with a hole diameter of 2% or 4 times the same as the plate thickness on a plate material of 2% of the specimen thickness. Considering that the transmission images of the specified through holes 2, 4, 6 are required to be visible on the film according to the test conditions, the transmittance meter 100 for radiation transmission test according to the embodiment of the present invention is used. In addition, following the characteristics of the dimensions described above for a plurality of pairs of slits to be processed into a transmission meter, in addition to this, the slit dimensions of the current line-pair type transmission meters are set as indicators for determining magnification. It is possible to process a dimension that is half or twice the thickness of the transmission meter.

  Using the line pair type transmissometer 100, bright and dark line pair images 9, 10, 11 formed by the slits 2, 4, 6 and the slit intervals 3, 5, 7 in the inspection film 200 of the radiation transmission test. As shown in FIG. 2, the line pair image 9 having a minimum 1T width among the light and dark line pair images 9, 10, and 11 by the slit pairs having the three types of dimensions in the inspection film image 8 is shown in FIG. However, there is a condition that the intermediate 2T width image 10 and the maximum 4T width dimension line pair image 11 can be clearly distinguished by visual observation (so that the separation state of the slits can be grasped). . Therefore, in accordance with this condition, standardization is performed by correcting the magnification at the time of image observation, and image data is stored and acquired under this condition. At that time, by making the shape of the through holes into rectangular slits 2, 4, 6, from the rectangular slit through holes 2, 4, 6 and the slit intervals 3, 5, 6 to the inspection film 200 after the radiation transmission by the radiation transmission test A pair of equal width lines 9, 10, 11 can be imprinted.

  Similarly, a millimeter scale line 13 and a 0.1 inch scale line 14 are linearly printed on two adjacent sides on a plate 12 on a film as shown in FIG. , 17 is used to obtain a digitized image (digital image data) 400 together with the radiation test film 200. At that time, paying attention to the line pair images 22, 23 and 24 shown in the film image as shown in FIG. 4, the line pair image 22 having the minimum width is decomposed as in the case shown in FIG. However, there is a condition that the image 23 having the intermediate width and the line pair image 24 having the maximum width can be clearly distinguished by visual observation. Therefore, in accordance with the conditions, the magnification is standardized by correcting the magnification at the time of image observation, and the image data is stored under these conditions. At this time, in order to easily evaluate on the digital image 18 the approximate size of the defect 19 that is imprinted on the digital image 18 of the inspection film 200, the scale images 20, 21 that are imprinted by the graduation printing lines. Is used. That is, by printing the scale, the approximate defect size can be estimated in comparison with the scale images 20 and 21 that have been copied. In FIG. 4, reference numeral 20 is formed as, for example, a millimeter memory line, and reference numeral 21 is formed as a 0.1 inch memory line.

Here, the dimension requirements of the line pair type transmissometer are summarized as follows. The relationship between the slit width W of the slit-shaped through-holes 2, 4, 6 and the slit interval S is as follows.
When the slit width W is 0.5T 1T = W = S (1)
When the slit width W is 1T slit 1T = W = S (2)
When the slit width W is 2T, 2T = W = S (3)
When slit width W is 4T slit 4T = W = S (4)
In the case of a slit having a slit width W of 8T, 8T = W = S (5)
Also, the relationship between the slit width W and the slit length L is
L> 7 * W (6)
It becomes. (2) (3) Each formula of (4) indicates that, as described above, the current perforated permeability meter 100 applies a thickness of a plate corresponding to 2% of the thickness of the test body 22 to the plate thickness. Considering that it is required that the specified through-hole image be visible on the inspection film according to the radiation transmission test conditions. This is a dimensional requirement that follows the above characteristics. In formula (1), the size of the through hole is smaller than the size of formula (2), and in formula (5), the slit size is set for the purpose of giving a larger slit size than that of formula (4). .

  Thus, in the formulas (2), (3), and (4), the width of the slit of the line pair type transmissometer 100 and the hole diameter of the perforated type transmissometer are set to the same size, so that the conventional perforated transmission The image of the line pair type transmissometer can be evaluated according to the discriminating degree requirement specification of the photometer, and there is an advantage that it can be used as an alternative to the conventional transmissometer.

  Also, as shown in the equation (6), the slit length L1, L2, L3 is sufficiently larger than the slit width W1, W2, W3 (here, larger than 7 times), so that the slit is formed in the inspection film after transmitting radiation. It becomes easy to see a line pair image captured in a bright and dark state by the dark image by 2 and the bright image by the slit interval 3.

  For the transmissometer 100 to be used, a line pair value determined by a standard or the like as an index of film resolution quality is set to the median value, and half of the line pairs are selected.

  In the film photographed with the transmissometer 100 and the digital data obtained by digitizing the film, the dark portion and its surroundings as shown by the line pair images 9, 10, 11 (see FIG. 2) by the transmissometer 100 of this embodiment. A pair of light and dark with the bright part is an image of a plurality of line pairs. Thus, when the film 200 having a plurality of pairs of images is digitized and observed as digital data, the magnification of the image is not increased unnecessarily, but the minimum width of the line pair images of the transmissometer 100 is not increased. The line pair image 9 is in a state where it is difficult to recognize the line as a line that has been decomposed (separated), but the middle line pair image 10 that is a resolution determination index can be confirmed after being decomposed (separated). When the resolution index MTF value measured from the contrast is 20% or more and the maximum line pair image 11 is clearly in a state where the filaments can be clearly decomposed and confirmed, the expansion is stopped.

  FIG. 5 is a flowchart showing a test procedure of the radiation transmission test in the present embodiment. In this test procedure, first, in step 25, the material and type of the line pair type transmissometer 100 to be used are determined in accordance with the material of the test body based on the material and thickness of the test body having a weld in the center. At that time, since the radiation transmission power varies depending on the material, the material of the line pair type transmissometer is selected and used as the material of the specimen.

  Next, film shooting is performed in step 26 using the selected line pair type transmissometer 100. As an example of film photography in a radiation transmission test using the line pair type transmissometer 100, as shown in FIG. 6, a radiation source 44 is placed at a position where radiation can be applied to the test body 46, and further a line pair. The permeation meter 45 is placed on the surface of the test body 46 on the radiation source 44 side. Further, the inspection film 47 is disposed on the surface of the test body 46 facing away from the radiation source 44, and the gradation meter 48 is disposed between the inspection film 47 and the test body 46 to perform film photographing. Film photographing is performed by irradiating radiation from the radiation source 44 toward the test body 46 and transmitting the radiation through the test body 46 including the welded portion 50, the gradation meter 48, and the line pair type transmissometer 45. This is done by exposing the film 47 and imprinting the transmitted image on the inspection film 47. Three line pairs 56, 57, and 58 as shown in FIG. 7 are imprinted on the inspection film 47. In addition, in FIG. 6, (a) The front view which shows the state at the time of a test, (b) is the figure which looked at the test body of (a) from the upper surface. In FIG. 6, l1 represents a distance between the test body 46 and the radiation source 44, l2 represents a distance between the line pair type transmission clock 45 and the inspection film 47, and l3 represents a reading width.

  In such a radiation transmission test, attribute data such as a management number, a test product name, and a registration date as shown in FIG. 8 is obtained in step 27 for each inspection film 47 having a line pair image photographed by the above-described method. Keep aside. In addition to the management number, test product name, and registration date, the attribute data includes, for example, test product name, number of gradation bits, customer name, film reading pitch, film reading density, film size, and transmission meter serial number. Numbers are also included.

  Here, FIG. 9 shows the tools used from the scanning of the inspection film 52 after photographing to the defect determination and their roles. In step 28, scanning conditions are set for converting the photographed inspection film 52 into digital image data using the scanner 60. Next, in step 29, the inspection films 52 to be converted into digital image data are set one by one in the scanner 60, and scanning processing is performed in step 30. The digital image data obtained by the scanning process of the procedure 30 is taken into a memory such as a hard disk of the computer 61 in the procedure 31, and an image based on the digital image data is displayed on the display 62. The data structure of the digital image data includes grayscale data indicating the degree of lightness and darkness at each coordinate position in the inspection film 52.

  FIG. 7 is a diagram showing an outline of an image based on digital image data of the inspection film 52 after photographing displayed on the display 62. Among the film images 53 taken on the inspection film 52 after photographing, line pair images 56, 57, 58 visualized through a line pair type transmissometer 45, an image 54 of a gradation meter 48, Images 55 of the welds 50 are respectively imprinted. Since these images are imaged on the film as visible images, the status of the line pair images 56, 57, 58, the image 54 of the gradation meter 48, and the image 55 of the welded portion 50 can be visually confirmed.

  Therefore, the concept of the MTF value widely used for the purpose of ensuring the resolution of the optical device is applied to the digital image data of the image displayed on the display 62. Here, in step 32, the resolution of the line pair image 57 having an intermediate dimension among the three line pair images 56, 57, and 58 is measured. This measurement is performed by obtaining the MTF value using the computer 61. Do.

  That is, in step 31, the digital image data of the image of the inspection film 52 after photographing is taken into the computer 61 and set as target data for measuring the MTF value. Next, in step 32, a coordinate symbol indicating the position of the measurement position of the MTF value of the line pair image 57 in the slit width direction of the line pair image 57, that is, in the direction perpendicular to the line pair of the bright and dark lines. x11, x12, and x13 are determined and set, and the measurement lines K1, K2, and K3 corresponding to these are determined in the direction of the slit width W of the slit 4 (see FIG. 1). The direction of the slit width W of the slit 4 means the direction of the arrangement of the three dark portions of the line pair image 57 on the screen of FIG. 6 displayed on the inspection film or the display. As in the present embodiment, by setting the shape of the slit 4 to be rectangular, the concentration distribution is measured for a plurality of positions, for example, measurement lines K1, K2, and K3, in a cross section perpendicular to the longitudinal direction of the slit 4. It becomes possible. Then, the density distribution in the direction P1 → P2 → P3 along the measurement lines K1, K2, and K3 perpendicular to the image of the slit 4 is separately measured at the coordinates X11, X12, and X13, that is, the measurement lines K1, K2, and K3. The density distribution at the coordinates X11, X12, and X13 measured separately for each of the lines K1, K2, and K3 is integrated for each position in the direction P1 → P2 → P3 perpendicular to the image of the slit 4, and as shown in FIG. A histogram is created in which the vertical axis indicates density and the horizontal axis indicates the position P1 → P2 → P3 perpendicular to the slit.

  Here, the density maximum value (= maximum value) that is the darkest image at the center of each of the dark lines P1, P2, and P3 that are images of the slit 4 is obtained, and the average value is B, that is, the center of the line pair interval, , A is the average value of the two brightest parts between P1 and P2, and between P2 and P3, and the density of the reference value C is the average value of the reference brightness parts such as both ends of the transmittance meter image. Are calculated respectively. In this way, by integrating or averaging the density obtained in the longitudinal direction of the dark lines P1, P2, and P3 of the line pair image and the direction perpendicular to the longitudinal direction, the influence of noise in the image data is reduced, and more An accurate MTF value can be calculated.

  In step 32, the MTF value of the line pair image is calculated using the value obtained by the above method. The MTF (Modulation Transfer Function) value is a value indicating the degree of contrast between light and dark images, and is expressed by the following equation, where I is the intensity level of light and dark.

MTF value = (I (bright) −I (dark)) / (I (bright) + I (dark)) (7)
Here, I (bright) is the highest intensity level value, and I (dark) is the lowest value. The larger the value, the higher the contrast. Generally, if this value is 0.2 or more, it is considered that identification is possible. Therefore, when the resolution of a line pair image is evaluated, 0.2 or more is set as a threshold value for discrimination.

Therefore, in the case of this example, the MTF value is calculated by the following equation.

MTF value = {(BC)-(AC)} / {(BC) + (AC)}
= (BA) / (B + A-2C) (8)
If this is 0.2, that is, 20% or more, the digitized film image is sufficiently identifiable, and an appropriate resolution can be obtained as a result of the radiation transmission test. Determine whether or not. The digital image data that has been determined to have an MTF value of 0.2 or more proceeds to the defect identification evaluation after step 34. If it is determined that the MTF value is less than 0.2, in step 33, the digital image data having the line pair image data that has been determined is discarded.

  The confirmed data of the visual equivalent resolution required as the inspection data is then enlarged on the display 62 in step 34. At this time, the image enlargement function of the computer 61 is used to slowly enlarge the image, and in step 35, it is visually confirmed whether or not the largest line pair image 58 in the image can be resolved and identified. Here, if the line pair image 58 can be decomposed and identified, it is determined in step 36 by visual observation whether or not the line pair image 57 having an intermediate size can be identified. In the resolution evaluation, the line-pair image 57 is guaranteed to have a resolution equivalent to visual observation. Therefore, if the image is enlarged, the line pair image 57 is surely adjusted to a state in which the filaments can be decomposed and confirmed.

  When the line pair image 57 can be identified by being decomposed, the image is further enlarged, and the boundary of whether or not the smallest line pair image 56 can be identified as the decomposed line in step 37 and step 44 is visually determined. The image enlargement is stopped in the state (step 38). Here, if the smallest line pair image 56 can be clearly decomposed and identified, the image is once reduced and the enlargement magnification correction procedures 34 to 37 are performed again.

  In this way, only digital image data whose resolution at the stage of the inspection film 52 is guaranteed and which is made constant based on an index with an enlargement magnification is stored as an inspection target image in step 39. Thereafter, in step 40, the digital image is observed on the display 62 and compared with a preset allowable value, thereby determining the presence / absence of a defect and evaluating the dimensions. The preset allowable value is set based on, for example, each piece of information such as a dimension and shape related to a defect defined in a standard standard in each industry. As a result, when it is determined that there is an unacceptable defect, it is determined that the product that has become the test body needs to be repaired and remanufactured. Therefore, in step 41, the test body is classified as a target for repair and remanufacturing.

  If an unacceptable defect is not recognized, it is determined in step 42 that the specimen has passed the radiation transmission test, and an inspection report is created. Here, attribute data such as the above-mentioned digital image data and test conditions are collected, and stored in the memory of the computer (PC) 61 as information for assuring the quality of the specimen in step 43. Since these pieces of information are stored electronically, when data disclosure is required depending on the situation, information disclosure using WEB or the like is also possible. This leads to improved searchability and advanced information management.

  The digital image data relating to the inspection film of the radiation transmission test digitized by the present embodiment quantitatively evaluates the identification resolution of the line pair image, thereby quantitatively guaranteeing the resolution of the film image data. The magnification at the time of observing a digital image can be made constant by using the difference in the degree of discrimination between the line pair images having two different dimensions. As a result, it is possible to reduce the risk of extremely different test observation conditions depending on the individual examiner, and to provide test results without variations. At the same time, the inspection film after photographing can be converted into a digital image, thereby simplifying the test result management in cooperation with IT technology, rationalizing the test process such as remote radiation test result judgment support, image processing technology It is possible to realize advanced inspection such as defect determination support that makes the best use of.

In FIG. 9, the scanner 60 can be seen from the above procedure.
1) Scanning condition setting 2) Scanning 3) Each function of temporarily storing scanning data. The computer PC
1) Scanning image capture 2) MTF measurement software activation 3) MTF measurement, determination 4) MTF measurement image, determination result data storage 5) Image recall 6) Image enlargement / reduction tool 7) Determination result image, determination result data storage 8) Attribute data registration, determination result and link 9) Each function of starting the examination report authoring software is provided. Further, the display 62 is
1) MTF measurement screen display 2) Enlargement magnification correction screen display 3) Defect evaluation screen display 4) Attribute data registration screen display 5) In addition, each processing function display function on the PC is provided.

  The above-described magnification correction can be adjusted in the same manner by using three different line pair images in the resolution confirmation chart shown in FIG. 3 instead of the line pair type transmissometer. Further, if a resolution confirmation chart with a scale as shown in FIG. 3 is used, an approximate value of the dimension of the defect projected on the digital image can be confirmed at a glance.

  In this embodiment, the RT film taken in steps 29 to 31 is scanned and converted into digital data, and the processing after step 32 is executed. As described above, the digital radiography technique is used. Needless to say, the digital image data may be acquired and the processing after step 32 may be executed.

<Second Embodiment>
FIG. 11 is a flowchart showing the procedure of the magnification correction method and the defect size evaluation method using the resolution confirmation chart of FIG.
In the resolution confirmation chart 300 used here, as shown in FIG. 3, three pairs of line pairs 15, 16, and 17 having different dimensions are printed. A line pair (hereinafter referred to as 5LP) having a line width of 0.1 mm and a line interval of 0.1 mm (hereinafter referred to as 5LP) is located at the center, and a line pair having a line width and line spacing that is half that of 5LP at the upper part ( In the lower part, a line pair (hereinafter referred to as 2.5LP) having a line width and line spacing twice that of 5LP is printed. 5LP is an index used to evaluate the performance of a digitizer when digitizing a radiation transmission test film. It is a general requirement for a film digitizer that 5LP can be read.

  In this processing procedure, first, the permeability meter used in procedure 63 is selected, and in step 64, the radiation transmission test film is photographed. At that time, the shape of the permeability meter 100 to be used is not limited. Next, the attribute information of the radiation transmission test film 200 obtained in step 64 is registered in step 65. The attribute information is, for example, as shown in FIG. When the attribute information is registered in step 65, scanning conditions for the film 200 are set in step 66. When the scanning condition is set in step 66, the radiation transmission test film 200 and the resolution confirmation chart 300 are simultaneously set in the scanner in step 67, and taken in the same image in step 68. The acquired digital image data 400 is taken into the computer 61 in step 69.

  Next, based on the line pair image (5LP) having an intermediate dimension in the resolution confirmation chart, the MTF value is calculated in step 70 in the same manner as the resolution evaluation using the transmissometer line pair image, and the image resolution evaluation is performed. Do. The image having the requested resolution is enlarged on the display 62 in step 72, and it is determined in step 73 whether 2.5LP can be confirmed as a line that is visually resolved by the inspector. If it can be confirmed as a disassembled line, it is confirmed in step 74 whether 5LP can be identified visually. In step 71, since the resolution of 5LP is guaranteed, the condition that the line pair can be decomposed and identified is always obtained if the image is enlarged. In this state, the enlargement magnification is gradually increased, and in step 75 and step 82, the enlargement condition is set within a range in which 10LP composed of the smallest dimension line cannot be decomposed and discriminated, and the enlargement is stopped in step 76. Under this condition, the image data is stored in the memory on the hard disk in the computer 61 as the inspection target image, and is set as the inspection determination required image.

  Next, in step 78, the presence / absence of a defect is determined by visual observation, and when the defect can be identified, the image of the scales 13 and 14 provided in the resolution confirmation chart of FIG. The scale image is compared with the defective part, and an approximate value of the defect size is measured.

  If it is determined in step 78 that there is an unacceptable defect, measures such as repair are performed in step 79. If no particularly unacceptable defect is found, an inspection report is created in step 80, and step 81 is performed. The report is saved at

  Using a resolution confirmation chart 300 having three types of line pairs provided with scales 13 and 14 and processing as described above, the magnification ratio at the time of observing the acquired image is corrected and dimension evaluation of the defect is performed. Can also be done easily.

  Other parts that are not particularly described are configured in the same manner as the first embodiment and function in the same manner.

  The present invention, for example, inspects internal defects in pipes and equipment welds in a non-destructive manner by shooting radiation on pipes and equipment welds in various plants and the surrounding area and shooting the pipes and equipment welds on a film. It can be used for

It is the upper side figure and elevation which show the line pair type permeability meter used for the 1st embodiment of the present invention. It is the observation image which digitized after film photography the line pair type permeability meter used for the 1st embodiment of the present invention. It is a conceptual diagram of the resolution confirmation chart used for the 1st Embodiment of this invention. It is a digital image schematic diagram at the time of digitizing simultaneously the resolution confirmation chart used for the 1st Embodiment of this invention, and a radiation transmission test film. It is a flowchart which shows the test procedure of the radiation transmission test in the 1st Embodiment of this invention. It is a figure which shows the state at the time of the test of the radiation transmission test in the 1st Embodiment of this invention. It is the figure which showed the display content on the display of the digital image data in the 1st Embodiment of this invention. It is a figure which shows the attribute data registration item of the radiation transmission test in the 1st Embodiment of this invention. It is explanatory drawing which showed the tool used from the scanning of the inspection film in the 1st Embodiment of this invention to defect determination, and its role. It is a histogram of the density | concentration of each position of the line pair image in the 1st Embodiment of this invention. It is a flowchart which shows the test procedure of the radiation transmission test in the 2nd Embodiment of this invention.

Explanation of symbols

1 Line pair type transmissometer plate material 2, 4, 6 Slit 3, 5, 7 Slit spacing,
13 Film as a basis for the resolution confirmation chart 13, 14 Scale of the resolution confirmation chart 15, 16, 17 Line pair printed on the resolution confirmation chart 44 Line source 45, 100 Line pair type transmissometer 46 Specimen 47, 200 Inspection film,
48 gradation meter 60 scanner,
61 Computer (PC)
62 Display 300 Resolution Confirmation Chart 400 Image (Digital Image Data)

Claims (17)

In a radiation transmission test apparatus used for a transmission test using radiation,
A plurality of radiation transmission test permeability meters and test specimens that are irradiated with radiation and that are exposed to the radiation transmission test permeability meters and the radiation transmission test permeability meters that are exposed to radiation transmitted through the test specimens. Control means for converting an image on the image recording medium of the slit into digital image data, and setting an enlargement magnification suitable for observing the image on the image recording medium using the line pair image converted into the digital image data as an index A radiation transmission test apparatus comprising:   2. The radiation transmission test apparatus according to claim 1, wherein the image recording medium is made of a film sensitive to radiation.   The radiation transmission test apparatus according to claim 1, wherein the image recording medium is made of a stimulable fluorescent film, and digital image data is acquired from the stimulable fluorescent film.   The radiation transmission test apparatus according to claim 1, wherein the image recording medium includes an image sensor, and digital image data is directly acquired from the image sensor. Comprising reading means for reading an image on the image recording medium,
4. The radiation transmission test apparatus according to claim 1, wherein the control unit converts image data read by the reading unit into digital image data. The image recording medium comprises a film sensitive to radiation,
Read means for reading the resolution confirmation chart as the same image data together with the film,
The radiation control apparatus according to claim 1, wherein the control unit converts image data read by the reading unit into digital image data.   The resolving power check chart includes a plurality of line pairs each having a plurality of pairs of lines each having a plurality of rectangular lines having different dimensions and a pair of intervals between lines having the same width as the line width of the lines. The radiation transmission test apparatus according to claim 6. Further comprising display means for displaying an image of the image recording medium output from the control means,
The control means visually confirms the line pair image in the digital image data displayed on the display means, and the slit part of the line pair image captured by a slit having a predetermined size among the line pair images. The radiation transmission test apparatus according to claim 1, wherein the digital image data is enlarged until it can be visually confirmed that an image between the slit portion and the slit portion is separated.   The control means enlarges the digital image data so as to meet a condition that it is difficult to visually confirm the separation state of the line pair image by a slit having a predetermined width smaller than the specified dimension. The radiation transmission test apparatus according to claim 8.   The radiation transmission test apparatus according to claim 9, wherein the predetermined small width is a half of the specified dimension.   The slit has a width equal to the plate thickness, 1/2 the plate thickness, 2 times the plate thickness, 4 times the plate thickness, and 8 types of the width of the plate thickness. The transmissometer for radiation transmission test has a plurality of pairs of slits each having a width and a pair of slit intervals having the same width as the slit width of the slit adjacent to each slit. The radiation transmission test apparatus according to claim 1.   12. A scale image is formed as information relating to dimensions on the resolution confirmation chart, and image data read together with the scale image is displayed on the display means. The radiation transmission test apparatus described.   The radiation transmission test apparatus according to claim 12, wherein the scale image is formed on at least one side of a rectangular film in units of millimeters and / or inches.   Radiation is applied to a transmission meter for a radiation transmission test and a specimen, and an image is recorded on the image recording medium with the radiation transmitted through the transmission meter for the radiation transmission test and the specimen, and recorded on the image recording medium. A radiation transmission test image for determining an appropriate magnification for observing an image recorded on the image recording medium, using as an index line pair images formed by a plurality of slits processed in the radiation transmission test permeability meter. Magnification correction method.   15. The method for correcting a magnification of a radiation transmission test image according to claim 14, wherein the image recording medium comprises any one of a film sensitive to radiation, an imaging plate, and an image sensor.   Radiation is transmitted to the transmissometer for the radiation transmission test and the test body, the film is exposed to the radiation transmitted through the transmissometer for the radiation transmission test and the test body, and the film is scanned with the scanner together with the film. A defect evaluation method for reading a resolution confirmation chart as the same image data, digitizing it as digital image data, and determining a rough defect dimension of the test object from a scale image based on the resolution confirmation chart. The defect evaluation method according to claim 16, wherein the scale image is formed on at least one side of a square film in units of millimeters and / or inches.

Images