JPH05332953A - X-ray inspection instrument - Google Patents

Abstract

PURPOSE:To accurately collect sectional projection data for a CT image of an object to be inspected from a two-dimensional X-ray detector. CONSTITUTION:X-rays emitted from an X-ray generating device 3 pass through an object to be inspected, and received by a two-dimensional X-ray detector 4. The fluoroscopic image of the object, thus picked up, is displayed on a monitor 5. A rectangular bar 2 having a surface 2a perpendicular to the axis of rotation of the object is mounted on a rotary stage 1 provided for rotating and vertically moving the object, and the position at which sides 2b, 2c of the surface 2a are superposed is found by vertically moving the bar 2. The position is stored. To form a clear CT image of the object, picture element data on the object is always taken in this position. The image is of a section of the object perpendicular to the axis of rotation of the object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an X-ray inspection apparatus,
In particular, non-destructively see through the inside of various industrial products, or observe fault planes to inspect and evaluate them X
It is suitable for use in a line inspection device.

[0002]

2. Description of the Related Art Conventionally, nondestructive inspection by X-ray fluoroscopy has been widely used for quality control and quality assurance of various industrial products. Recently, due to advances in semiconductor technology and computer technology, real-time two-dimensional X-ray detectors such as an X-ray image intensifier (hereinafter referred to as X-ray II) and an X-ray vidicon, and an image processing apparatus are provided. The combined real-time X-ray fluoroscope was commercialized,
It is becoming popular as an online quality inspection device on the production line.

For example, by using a micro-focus X-ray tube, an X-ray fluoroscopic image is magnified at a magnifying power determined by the arrangement of a subject and an X-ray detection device, thereby achieving high resolution and IC.
An X-ray fluoroscopy system capable of obtaining a fluoroscopic image with a resolution of several tens of μm is commercially available as an inspection apparatus for microelectronic components such as capacitors and capacitors. However, in such an apparatus, it is difficult to analyze a perspective image if the internal structure is complicated because a three-dimensional object is projected in two dimensions.

To solve such a problem, X
A line CT device may be used. Since it is possible to obtain an image of a tomographic plane without cutting or breaking the subject, it is being used as a very excellent nondestructive inspection device. However, in the case of industrial products, unlike the X-ray CT apparatus for the human body, the position of the subject is not fixed, so it is necessary to observe the entire area of the subject with the X-ray CT apparatus.

Further, at this time, since it is necessary to image with a slice width that matches the spatial resolution of the CT image, there is a problem that it takes too much time to image the entire subject with CT. Therefore, attempts have been made to improve the measurement accuracy of an X-ray fluoroscopic examination and shorten the examination time by combining a real-time X-ray fluoroscopic apparatus and an X-ray CT apparatus.

For example, in a document (Kenji Okuma, Junichiro Sekida: Nondestructive inspection, Vol.39, N.9A, 763), CT imaging is performed while observing a fluoroscopic image of a subject using an existing real-time X-ray inspection apparatus. Is feasible.
This is an X-ray I.D. I. Using the X-ray I.D. I. It is realized by A / D converting the X-ray fluoroscopic image by and extracting the projection data of the tomographic plane of the subject necessary for CT image reconstruction.

By the way, since A / D conversion of a perspective image in a general image processing apparatus is performed according to the order of scanning lines, it is easy to extract projection data in units of scanning lines. That is, instead of the one-dimensional array X-ray detector generally used in the X-ray CT apparatus, the X-ray I.D. I.
The object projection data necessary for performing the CT image reconstruction processing is acquired by utilizing the pixel rows on one or several scanning lines at certain positions.

However, when the subject is rotated to collect the projection data, it is necessary to always obtain the projection data of the same tomographic plane. To do so, it is necessary to make the rotation axis and the plane including the tomographic plane to be observed orthogonal to each other. Therefore, when collecting projection data, it is important to position the scanning line of the two-dimensional detector so as to be orthogonal to the rotation axis of the subject.

However, in the existing X-ray inspection apparatus, X-ray CT is used.
There is a possibility that the scanning line and the subject rotation axis are not orthogonal to each other with the accuracy required by the apparatus, or even if they are set accurately at first, they may not be orthogonal due to aging.
There are problems such as.

[0010]

As described above, the existing real-time X-ray inspection apparatus or X-ray I.D. I. Like 2
When the tomographic plane projection data of the subject is taken out from the pixel array on the scanning line using a dimension detector or the like and the CT image is reconstructed from the projection data, with the accuracy required by the X-ray CT apparatus. In some cases, the scanning line and the subject rotation axis are not exactly orthogonal.

Even if the orthogonal state can be set with high accuracy at first, there are cases where the orthogonal state disappears due to aging. In such a case, the tomographic plane of the projection data obtained by rotating the subject is different for each projection data, and there is a problem that a clear CT image cannot be obtained. In view of the above problems, the present invention provides a two-dimensional X
An object of the present invention is to enable accurate acquisition of tomographic plane projection data for a CT image of a subject from a line detector.

[0012]

An X-ray inspection apparatus according to the present invention includes a two-dimensional X-ray detector for detecting X-ray fluoroscopic images by receiving X-rays emitted from an X-ray generator and transmitted through a subject. , The X-ray fluoroscopic image detected by the two-dimensional X-ray detector is A /
An image processing device for D-converting and outputting, a monitor device for displaying the X-ray fluoroscopic image output from the image processing device, and a device for rotating or vertically moving the subject. And a subject rotating stage that rotates or moves a square rod having a plane orthogonal to the subject rotation axis in the vertical direction, and a vertical stage that moves the square rod. Means for reading the coordinates of the line of intersection between the plane including the X-ray generation source orthogonal to the sample rotation axis and the fluoroscopic image plane detected by the two-dimensional X-ray detector, and the line of intersection in synchronization with the rotation of the subject. An X-ray inspection apparatus comprising: means for reading the tomographic plane projection data for the CT image of the subject from the coordinates.

[0013]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a plan view of a schematic configuration when collecting projection data for correcting image data, and FIG. 2 is a side view of the same. As is apparent from FIGS. 1 and 2, when the X-ray inspection apparatus according to the present embodiment is used, the rectangular rod 2 having the surface 2a perpendicular to the rotation axis is placed on the object rotation stage 1 in the X-ray irradiation direction. And square bar 2
Place them so that their longitudinal directions are orthogonal to each other.

When the X-ray tube 3 irradiates the square rod 2 with X-rays,
The perspective image of the square rod 2 is detected by the two-dimensional X-ray detector 4 and displayed on the monitor TV 5. An example of this display is shown in FIG. The perspective image of this FIG.
Since the lines do not hit in parallel, the sides 2b and 2 of the square bar 2
It shows that both c are observed.

Therefore, the subject rotary stage 1 is moved up and down in a direction parallel to the rotation axis so that X-rays parallel to the surface 2a can be obtained. That is, as shown in FIG. 4, the subject rotating stage 1 is moved up and down so that the sides 2b and 2c of the square bar 2 are seen through each other as shown in FIG. In FIG. 4, 3a indicates a line parallel to the scanning line, and 3b indicates a deviation angle between the scanning line and the rotation axis.

As a result of performing such an operation, the position where the sides 2b and 2c of the square rod 2 overlap shows the position where the X-ray radiation plane orthogonal to the rotation axis of the subject is obtained. The detected perspective image is A / D converted by the image processing device 6 and sent to the computer 7 as a digital image. The image sent to the computer 7 is subjected to binarization processing and edge detection processing, and the coordinates on the image at the position where the edges 2b and 2c of the square bar 2 on the image overlap are read and the computer 7 Memorized in.

When reading the tomographic projection data of the subject, the computer 7 always reads the pixel data at this position and uses them as CT image reconstruction data to obtain a clear CT image. To

[0018]

EXAMPLE An example of the X-ray inspection apparatus of the present invention will be described below. In this embodiment, the square rod 2 has a cross section of 5 mm square, a length of 200 mm, and is made of aluminum, and the two-dimensional X-ray detector 4 is an X-ray I.D.
I. Is used.

Further, as the image processing device 6, X-ray I.D. I.
A device capable of converting an analog image signal from the above into a digital image having 512 × 512 pixels was used. With these, a perspective image of the square rod 2 is taken, and when the two sides of the square rod 2 overlap, the image signal is digitized, and
Binarization processing was performed to detect edges, and then the coordinates of the edges on the image were stored in the computer 7.

Next, a test piece 8 having a structure as shown in FIG. 5 was placed on the object rotating stage 1 and projection data for CT image reconstruction was collected. At this time, the CT image based on the projection data obtained according to the side coordinates obtained by the above method and the C based on the projection data obtained from the scanning line passing through the left end of the side coordinates.
The image quality of T images was compared.

From these images, the line profile of the pixel density level at the position shown in FIG. 6 was read. The result is shown in FIG. 7. In FIG. 7, the horizontal axis represents the position on the image, and the vertical axis represents the value normalized by the maximum value of the read image density. As can be seen from this, it is possible to obtain a clear image with less blur when the projection data collection is corrected.

[0022]

Since the present invention is constructed as described above,
It is possible to obtain the projection data on the tomographic plane of the subject orthogonal to the rotation axis of the subject. As a result, a clear CT image can be obtained, and the tomographic plane of the subject can be satisfactorily observed while observing the fluoroscopic image of the subject. Further, adjustment with respect to a secular change that is orthogonal to the rotational axis of the subject can be easily performed, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a plan view of a schematic configuration for collecting a corrected image of projection data.

FIG. 2 is a side view of a schematic configuration for collecting a corrected image of projection data.

FIG. 3 is a diagram showing alignment of correction image collection, and is a diagram showing a state in which the positions are displaced.

FIG. 4 is a diagram showing alignment of correction image collection, and is a diagram showing a state where the positions are aligned.

FIG. 5 is a perspective view showing the shape of a subject used for explaining the effect of the present invention.

FIG. 6 is a diagram showing the positions of line profiles used to explain the effect of the present invention.

FIG. 7 is a diagram showing a line profile used for explaining the effect of the present invention.

[Explanation of symbols]

 1 specimen rotating stage 2 square bar 2a square bar surface 2b square bar side 2c square bar side 3 X-ray tube 4 two-dimensional X-ray detector 5 monitor TV 6 image processing device 7 computer 8 test piece

Claims (1)

[Claims] 1. A two-dimensional X-ray detector for detecting an X-ray fluoroscopic image by receiving X-rays emitted from an X-ray generator and transmitted through a subject, and X detected by the two-dimensional X-ray detector. A perspective image
An image processing device for performing D / D conversion and output, a monitor device for displaying the X-ray fluoroscopic image output from the image processing device, and a device for rotating or vertically moving the subject. The subject rotation stage that rotates or moves the square rod having a plane orthogonal to the subject rotation axis in the vertical direction, and by moving the square rod in the vertical direction, A plane including an X-ray generation source orthogonal to the rotation axis of the subject and a two-dimensional X
Means for reading the coordinates of the line of intersection with the fluoroscopic image plane detected by the line detector, and reading the tomographic plane projection data for the CT image of the subject from the coordinates of the line of intersection in synchronization with the rotation of the subject. An X-ray inspection apparatus comprising: