JPH0512424A - Scattered beam tomographic image photographing device - Google Patents

Abstract

PURPOSE:To provide the scattered beam tomographic image photographing device which can accurately display the material distribution of a reagent to a transmitted X ray direction as a two-dimensional image. CONSTITUTION:X rays outputted from an X-ray tube 15 are turned to pencil X ray beams 20 to be scanned in the shape of a fan by a linear collimator 16 and a rotary collimator 17. This pencil X ray beam 20 is abutted to a reagent 21, scattered X rayed are generated and detected by a scattered X ray quantity detector 23. Since the reagent 21 is continuously rotated by a turn table 22 while being irradiated with the pencil X ray beams 20 during scanning, the scattered X ray quantity detector 23 outputs scattered X ray data for a half circle. The outputs of the scattered X ray quantity detector 23 are A/D converted by a scattered X ray quantity data collector 24 and turned to scattered X ray projection data to produce the scattered X ray tomographic image of the reagent 21. These projection data are recomposed by an image recomposer 25, and the tomographic image is displayed on a CRT display 26.

Description

Detailed Description of the Invention

[Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates an object to be inspected with radiation and measures scattered rays from the object to be inspected, thereby obtaining a scattered ray tomographic image of the object to be inspected and performing a fluoroscopic inspection. The present invention relates to an image capturing device.

[0002]

2. Description of the Related Art As one of the apparatuses for performing a fluoroscopic inspection of an object to be inspected using radiation, there is a bag inspection apparatus for inspecting baggage to be brought into an aircraft at an airport. The outline of the conventional X-ray inspection apparatus for baggage inspection will be described below with reference to the drawings.

In FIG. 4, an X-ray tube 1 irradiates a conical X-ray 2. Reference numeral 3 is a linear collimator, which collimates the conical X-ray 2 to be irradiated onto a fan-shaped X-ray beam 4. Reference numeral 5 denotes a rotary collimator, which transforms the fan-shaped X-ray beam 4 into a fan-shaped flying spot pencil X-ray beam 6 which is vertically scanned. An inspected object 7 is conveyed by a conveyor 8 at a constant moving speed, and the pencil X-ray beam 6 is vertically scanned on the inner surface of the inspected object 7. Reference numeral 9 denotes a transmission X-ray dose detector, which detects the transmission X-ray dose transmitted through the inspection object 7 and outputs a transmission X-ray dose signal. 10 is scattered X
It is a dose detector that detects the scattered X-ray dose of the backscattered X-rays 11 from the inner surface of the inspection object 7 and outputs a scattered X-ray dose signal. Reference numeral 12 is a transmission X-ray dose data collector, which is a spot position signal of the pencil X-ray beam 6 detected by a position detector (not shown) and a transmission X-ray at that spot position.
The dose signal is A / D converted to collect spot position data and transmitted X-ray dose data. A scattered X-ray dose data collector 13 A / D converts the spot position signal of the pencil X-ray beam 6 detected by a position detector (not shown) and the scattered X-ray dose signal at the spot position. Collect the spot position data and scattered X-ray dose data. 14 is C
RT display, transmission X-ray dose data collector 12
1 frame of transmitted X-ray dose data is image-processed and a transmitted X-ray image is displayed in red on the screen, and scattered X-ray dose data from collector 13 is scattered by 1 frame. The dose data is image-processed and the scattered X-ray image is displayed in green on the screen.

In the X-ray inspection apparatus for inspecting luggage thus constructed, the conical X-ray 2 from the X-ray tube 1 is vertically scanned in a fan shape by the linear collimator 3 and the rotary collimator 5. Collimate to a flying spot pencil X-ray beam. Since the inspected object 7 continuously moves on the conveyor 8 so as to cross the pencil X-ray beam 6, the pencil X-ray beam 6
The line beam 6 raster-scans the inner surface of the object 7 to be inspected. In this way, the transmitted X-ray dose and scattered X-ray dose from the entire inner surface of the inspection object 7 are detected, and the CRT display 14
The transmitted X-ray image in red and the scattered X-ray image in green are superimposed and displayed.

In the transmitted X-ray image, a dangerous metal object such as a pistol or a knife inside the object 7 to be inspected can be detected. Non-metals such as plastic bombs and narcotics, which cannot be detected by transmission X-ray images in scattered X-ray images, can be detected.

[0006]

In the conventional apparatus, the X-ray transmission inside the inspection object is performed by raster-scanning the inspection object.
The line integral value information of the scattering coefficient distribution according to the dose is displayed as the concentration value according to the information value.

Therefore, in such a scattered X-ray image of a plane perpendicular to the transmitted X-ray direction, even if the substance distributions in the transmitted X-ray direction are different, it is possible to distinguish the substances if the line integral values are the same. There is a problem that you cannot do it. Therefore, an object of the present invention is to provide a scattered radiation tomographic imaging apparatus capable of accurately displaying the substance distribution in the transmitted X-ray direction. [Constitution of Invention]

[0008]

In order to achieve the above object, in the first invention, a radiation generating means for generating a radiation and a radiation generated by the radiation generating means are used as a pencil radiation beam. To the fan-shaped surface showing the scanning range when the pencil radiation beam is scanned in a fan shape, which has a scanning means for collimating and scanning in a fan shape and a rotation axis orthogonal to the pencil radiation beam. A means for rotating the inspected object with respect to the pencil radiation beam having parallel planes of rotation, and a rotational movement of the inspected object with respect to the pencil radiation beam scanned in a fan shape by this rotating means. Then, scan the pencil radiation beam on the inspected object,
Scattered radiation detecting means for detecting scattered radiation scattered from the inspection object, and the scattered radiation data detected by the scattered radiation detection means are subjected to reconstruction calculation processing to obtain a scattered radiation tomographic image of the inspection object. Reconstruction calculation processing means for reconstructing and outputting a video signal of the image, and image display means for displaying a scattered ray tomographic image of the object to be inspected by the video signal output from the reconstruction calculation processing means. It is characterized by that.

Further, in the second invention, a radiation generating means for generating the radiation, and a scanning means for collimating the radiation generated by the radiation generating means into a fan-shaped radiation beam and scanning the object to be inspected. , Having a rotation axis orthogonal to the fan-shaped radiation beam surface scanned by the scanning means and having a rotation surface parallel to the fan-shaped radiation beam surface, the object to be inspected with respect to the fan-shaped radiation beam. The rotating means for rotating and the longitudinal direction of the fan-shaped radiation beam surface are arranged in parallel,
A slit for passing scattered rays generated by the fan-shaped radiation beam on the object to be inspected, a multi-channel type scattered ray detecting means having a detection surface parallel to the slit, and a scattered ray detector detected by this scattered ray detecting means. -Reconstruction calculation processing means for reconstructing a scattered ray tomographic image of the inspection object by performing reconstruction calculation processing on the data and outputting a video signal of the image, and a video signal output by the reconstruction calculation processing means. And an image display unit for displaying a scattered ray tomographic image of the object to be inspected.

[0010]

Embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 15 denotes an X-ray tube, which irradiates a conical X-ray. Reference numeral 16 is a linear collimator having a slit provided in the horizontal direction, and collimates a conical X-ray 17 with a fan-shaped X-ray beam 18. A rotating collimator 19 collimates the fan-shaped X-ray beam 18 onto a flying pencil X-ray beam 20 which is horizontally scanned on the horizontal plane. Reference numeral 21 is a cylindrical inspection object, which is a circular table 2 rotating at a constant speed.
It is mounted on top of 2 and has a rotating motion. A scattered X-ray dose detector 23 is provided between the circular collimator 19 and the rotary table 22 to detect the backscattered X-ray dose from the inspection object 21 and output a scattered X-ray dose detection signal. . 24
Is a scatter X-ray dose data collector. The scatter X-ray detection signal is A / D converted and the scatter X-ray image data is accompanied by a scanning position signal of a pencil beam X-ray from a position detector (not shown). Output to. An image reconstructor 25 reconstructs a scattered X-ray tomographic image from the collected scattered X-ray dose data and outputs a video signal thereof. Reference numeral 26 is a CRT display, which displays a scattered X-ray tomographic image of the object 21 to be inspected on the screen from the video signal.

The operation of the embodiment thus constructed will be described. A conical X-ray 17 emitted from the X-ray tube 15 has a parallel fan-shaped field of view through a linear collimator 16 and a circular collimator 19, and has a flying pencil X-ray beam 20 for scanning left and right. Becomes The flying pencil X-ray beam 20 which is scanned in a fan shape is applied to the rotating inspection object 21 on the rotation table 22. The inspection object 21 is rotated 360 °, and at this time, the inspection object 2 is rotated at a constant angle.
The backscattered X-ray dose reflected from 1 is a scattered X-ray dose detector 2
Detect with 3. In this way, the scattered X-ray dose data collector 24 collects the scattered X-ray dose data from the entire circumferential direction of the horizontal tomographic plane of the inspection object 21. Scattered X-ray dose data collector 24
Then, each scattered X-ray dose data is A / D converted,
The scattered X-ray projection data is output. With the image reconstructor 25,
The scattered X-ray projection data is used to reconstruct a scattered X-ray tomographic image of the horizontal tomographic plane of the inspection object 21, which is the inspection surface, and the image signal thereof is output to the CRT display 26. The scattered X-ray tomographic image for the inspection surface of the inspection object 21 is displayed on the CRT display 26. In this way, information obtained by integrating scattered X-rays in the transmission direction of the flying pencil X-ray beam 20 can be obtained from the scattered X-rays generated by the flying pencil X-ray beam 20 hitting the inspection object 21. . Therefore, by processing this scattered X-ray dose data as projection data by the tomographic image reconstruction algorithm of the CT scanner,
A tomographic image is obtained by scattered X-rays.

According to this embodiment, the flying pencil X-ray beam 20 is horizontally fan-shaped scanned on the rotating inspected object 21, and the scattered X-ray dose from the inspected object 21 causes
A scattered X-ray tomographic image of the inspection object 21 can be obtained.
Therefore, a two-dimensional distribution image of a substance that scatters X-rays well and a substance that does not scatter X-rays can be obtained. Although the object to be inspected is rotated in the present embodiment, the same effect can be obtained by rotating the X-ray tube, collimator system, and X-ray detection system.

Next, FIG. 2 shows another embodiment. In the drawing, a horizontal collimator 28 provided in front of the X-ray tube 27 and provided with slits in the horizontal direction causes a horizontal beam to be emitted.
Create Mu 29. The transmission X-ray dose detector 30 is arranged so as to face the slit of the linear collimator 28 in parallel, and detects the fan-shaped X-ray beam 29. Between the X-ray tube 27 and the transmitted X-ray dose detector 30, a rotary table 31 is mounted with an object 32 to be inspected, and rotates around a rotation axis perpendicular to the fan-shaped X-ray beam 29. A scattering X-ray slit 33 is fixed on the rotating table 31 in parallel with the fan-shaped X-ray beam 29.
An X-ray television 34 is arranged above the scattered X-ray slit 33 with its detection surface parallel to the beam 29. The transmission X-ray dose detector 30 is sequentially connected to the transmission X-ray dose data collector 35, the image reconstructor 36, and the CRT display 37. The X-ray television 34 uses the scattered X-ray dose data collector 3
8, the image reconstructor 39, and the CRT display 40. A fan-shaped X-ray beam 29 formed by an X-ray tube 27 and a collimator 28 is scanned by a rotating table 31 on a rotating inspection object.

A transmission X-ray dose detector 30 composed of a 512-channel line sensor, and a transmission X-ray of each channel to be inspected are incident. At the same time, a part of the fan-shaped X-ray beam 29 irradiated on the inspected object 32 is scattered in all directions, and a part of the scattered X-rays thus scattered passes through the scattering X-ray slit 33, so that the X-ray television It is incident on the detection surface 34.

The rotation table 31 has a data collection start point (0 °
Incident transmission X while rotating 1 ° from the moment of passing position)
The lines are measured and collected as a set of data called a view. The transmission X-ray dose detector 30 has 1 view data for 1 channel each and 512 data items for 512 channels.
It is The data of one view of the X-ray television 34 is as follows.

A set of parallel lines A ... B on the fan-shaped X-ray beam 29.
A part of the scattered X-rays scattered on C pass through the scattered X-ray slit 33, and a set of parallel lines a ... B on the detection surface.
... becomes a scattered X-ray image of c. The scanning direction of the X-ray television 34 is the direction of parallel lines, and scanning is performed in the order of a ... b ... c, and the output of the X-ray television is output. The scattered X-ray dose data collector 38 integrates the output during each scan a ... b ... c,
Collect 512 sets of data proportional to the scattered X-ray intensities corresponding to each of the sets of parallel lines a ... B ... C. Rotation tee
During the next minute rotation 1 ° to 2 ° of the bull 31, one view of data is similarly collected.

When the rotary table 31 is rotated up to the 180 ° position, a total of 180 views of data are collected, the scan is completed, and when the scan is completed, 512 for each of the transmitted X-rays and scattered X-rays. × 180 pieces of data are collected.
The data of the transmission X-ray dose detector 30 is obtained by the conventional method.
The X-ray tomographic image is reconstructed and displayed.

The data of the X-ray television 34 is the inspection object 32.
Is proportional to the integrated value of the scattered X-rays emitted from the respective lines of the parallel lines a ... B ... C on the measurement surface, and the angle of the parallel lines is 0 ° to 180 ° with respect to the inspection object 32. It is data that spans a period. If the X-ray absorption by the device under test 32 is small, these data are a method of traversing and rotating one radiation source and one channel detector with respect to the device under test, so-called first generation CT. It has the same format as the data obtained by the scanner and reconstructs the scattered X-ray tomographic image by the same algorithm. In the embodiment configured as described above, the measurement surface of the object to be inspected can be inspected by two kinds of images, the scattered X-ray tomographic image and the transmitted X-ray tomographic image. With the scattered X-ray tomographic image, it is possible to pattern the distribution of substances such as non-metals that were not visible in the transmitted X-ray tomographic image.
Further, the scattered X-ray tomographic image uses the conventional first generation reconstruction algorithm and can be reconstructed relatively easily as compared with the third generation reconstruction algorithm.

In this embodiment, an X-ray television was used as a detector for scattered X-rays, but a visible light line sensor 41 consisting of a photodiode array shown in FIG. 3 and a linear scintillator attached thereon. It may be a detector composed of 42. Aluminum 43 is vapor-deposited on the surface of the scintillator 42 of this detector to reflect and shield light. It can be applied if the sensor surface of each channel is long and made parallel to each other.

[0020]

According to the present invention, it is possible to obtain a tomographic image of the object under inspection by scattered radiation. Therefore, it is possible to provide a scattered ray tomography apparatus capable of obtaining a distribution of a substance that easily scatters radiation and a substance that does not scatter radiation as a two-dimensional image, and that enables highly accurate measurement and inspection.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a scattered X-ray tomographic imaging apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a scattered X-ray tomographic imaging apparatus according to another embodiment of the present invention.

FIG. 3 is an external view of a scattered X-ray dose detector that can be used in another embodiment.

FIG. 4 is a configuration diagram of a conventional fluoroscopic inspection apparatus.

[Explanation of symbols]

1 ... X-ray tube, 2 ... Conical X-ray, 3 ...
Linear collimator, 4 ... fan-shaped X-ray beam, 5 ... rotating collimator, 6 ... pencil X-ray beam, 7 ...
Inspection object, 8 ... Conveyor, 9 ... Transparent X
Dose detector, 10 ... Scattered X-ray dose detector, 11 ... Backscattered X-ray, 12 ... Transmitted X-ray dose data collector,
13 ... Scattered X-ray dose data collector, 14 ... CRT display, 15 ... X-ray tube, 16 ... Linear collimator, 17 ... Conical X-ray, 18 ... Fan-shaped X-ray beam
Mu, 19 ... Rotating collimator, 20 ... Pencil X
Line beam, 21 ... Inspected object, 22 ... Circular table, 23 ... Scattered X-ray dose detector, 24 ... Scattered X-ray dose data collector, 25 ... Image reconstructor, 2
6 ... CRT display, 27 ... X-ray tube,
28 ... Linear collimator, 29 ... Fan-shaped X-ray beam,
30 ... Transmission X-ray dose detector, 31 ... Rotation table,
32 ... Inspected object, 33 ... Scattered X-ray slit,
34 ... X-ray television, 35 ... Transmission X-ray dose data collector, 36 ... Image reconstructor, 37 ... CRT display,
38 ... Scatter X-ray dose data collector, 39 ... Image reconstructor, 40 ... CRT display, 41 ... Visible light line sensor, 42 ... Scintillator, 43 ... Aluminum.

Claims (2)

[Claims] 1. A radiation generating means for generating a radiation, a scanning means for collimating the radiation generated by the radiation generating means into a pencil radiation beam and scanning it in a fan shape, and a scanning means orthogonal to the pencil radiation beam. Means for rotating the object to be inspected with respect to the pencil radiation beam, having a rotation surface parallel to the sector surface showing the scanning range when the pencil radiation beam is scanned in a fan shape. The rotating means causes the inspected object to rotate with respect to the pencil radiation beam scanned in a fan shape, so that the inspected object is scanned with the pencil radiation beam and scattered from the inspected object. Scattered radiation detecting means for detecting scattered radiation, and the scattered radiation data detected by this scattered radiation detection means is subjected to reconstruction calculation processing to reconstruct a scattered radiation tomographic image of the inspection object, and Output video signal That a reconstruction processing means, the image signal output from the reconstructing arithmetic processing means, the scattered radiation tomographic imaging apparatus and an image display means for displaying a scattered ray tomographic image of the object to be inspected. 2. A radiation generating means for generating radiation, and the radiation generated by this radiation generating means is fan-shaped radiation beam.
A rotating surface parallel to the fan-shaped radiation beam surface, which has a scanning means for collimating the beam and scanning the inspected object, and a rotation axis orthogonal to the fan-shaped radiation beam surface scanned by the scanning means. And a rotating means for rotating the object to be inspected with respect to the fan-shaped radiation beam, and its length direction is arranged in parallel to the surface of the fan-shaped radiation beam. The multi-channel type scattered ray detecting means having a detection surface parallel to the slit and the slit for passing the scattered ray generated by the above, and the scattered ray data detected by this scattered ray detecting means are subjected to reconstruction calculation processing. The scattered radiation tomographic image of the inspected object is reconstructed by outputting the image signal of the image, and the scattered radiation tomographic image of the inspected object is generated by the image signal output from the reconstruction operation processing means. Image display means for displaying an image Scattered radiation tomographic imaging apparatus having a.