JPH02134599A - Image pickup device - Google Patents

Abstract

PURPOSE:To enable a high quality image pickup with a short period irradiation of a radioactive radiation by making a target to receive a shock of an accelerated electron beam be of a disc concave against an object to be inspected and, by providing a slit between the target and the object. CONSTITUTION:An X-ray source 4 has a target 22 to be collided with an accelerated electron beam 21 and a slit 23 placed at an X-ray detector side of the target. An incident X-ray to a detector element 6a that is a certain specific channel of a detector 6 which consists of arcuately arranged detector elements, is an X-ray which a specific part 22a of the target 22 to which an element 6a faces through an opening of the slit 23, generates. In this way, detectors 6 correspond to whole area of the target 22. Therefore, even if a large sized target is used, the X-ray source corresponding to the element 6a can be treated as a point and thus a high resolution sectional image or projected image can be attained. Also, as the electron beam 21 collides with a whole area of the large sized target 22, a beam dose can be intensified without any local overheat.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an imaging device used for non-destructive testing, medical diagnosis, etc., which can obtain a tomographic image of an object to be inspected.

(Prior art) This type of imaging device irradiates radiation such as X-rays from the entire circumference of the object to a position where a tomographic image of the object is to be obtained, and then uses a radiation detector to irradiate radiation such as X-rays on the side facing the radiation source. The amount of transmission is measured to obtain projection data, and the tomographic image is constructed from this projection data. This imaging device is known as a CT scanner, and from the tomographic images obtained at each slice position, information regarding the measurement of the object to be inspected,
For example, it is widely used for medical and industrial purposes because it can obtain the dimensions, cross-sectional shape, presence or absence of defects, etc. of the object to be inspected.

Therefore, currently used CT scanners use an X-ray tube or linac as their radiation generating device. These radiation generating devices accelerate electrons to collide with a metal target, and generate X-rays by bremsstrahlung radiation. These radiation generating devices are general-purpose products that are also used for transmission imaging such as radiography, and are easily available.

In the above-mentioned general-purpose radiation generating apparatus, in order to increase the resolution of transmission imaging, the source of radiation is usually narrowed down to a point-like source as much as possible.

When using a point-like source as described above, local heat generation of the target due to electron collision increases, making it difficult to increase the radiation dose of the radiation generating device.

(Problem to be solved by the invention) As mentioned above, since the radiation generating device used in the conventional imaging device could not produce a large amount of radiation, the amount of radiation that is detected after passing through the inspected object is The S/N ratio of the data was low, and it was not possible to avoid deterioration in image quality due to the generation of image noise. Furthermore, in order to increase the S/N ratio in a conventional imaging device, the measurement time may be made extremely long. However, if the measurement time is made extremely long, changes in the position of the radiation generator due to changes in ambient conditions,
Fluctuations in the intensity of the generated radiation, fluctuations in detector characteristics, etc. affected the image quality, making it impossible to obtain good images.

The present invention was made based on the above-mentioned circumstances, and an object of the present invention is to provide an imaging apparatus that can obtain a tomographic image or a projection image of good image quality by irradiating radiation for a short time.

[Structure of the Invention] (Means for Solving the Problems) The imaging device of the present invention includes an X-ray source and an X-ray detection device disposed opposite to the X-ray source, and an X-ray detection device placed between them. In an apparatus for capturing a projected image or a tomographic image of an object to be inspected, the target receiving the accelerated electron beam of the X-ray source is a disc-shaped concave facing the object to be inspected, and the target A slit is arranged between the object to be inspected,
The X-ray detection device is characterized by comprising a plurality of detection elements arranged on a circular arc centered on the opening of the slit, with a detection axis matching the diameter of the circular arc.

(Function) In the imaging device of the present invention having the above configuration, each of the plurality of detection elements of the X-ray detection device corresponds to a specific portion of the target through the opening of the slit. Therefore,
Even when a large target is used, the X-rays that pass through the object to be inspected and enter each detection element can be considered as being emitted from a substantially point-shaped source. Since a large target is used as described above, it is possible to increase the dose of the X-ray source, and in combination with the substantially point-shaped X-ray source described above, it is possible to achieve good projection with high resolution and image quality. images or tomographic images can be obtained.

(Example) Fig. 1 is a schematic diagram showing the overall configuration of one embodiment of the present invention, and Fig. 2 is a schematic diagram showing the overall configuration of an embodiment of the present invention.
The figure is a schematic plan view showing the relationship between the X-ray source and the X-ray beam in the embodiment, and FIG. 3 is a schematic side view showing the relationship between the X-ray source and the X-ray beam. In these figures, an object to be inspected 1 is placed on a turntable 3 rotated by a drive mechanism 2, and an X-ray source 4 has a fan-shaped X-ray beam 5 whose limit touches the periphery of the turntable 3.
It is assumed that it radiates. Furthermore, on the opposite side of the X-ray source 4 with the turntable 3 in between, an arc-shaped X-ray detector 6 centered on the radiation point of the X-ray source 4 is installed. Note that this X-ray detector 6 is composed of a plurality of detection elements whose detection axis is directed toward the radiation point of the X-ray source, and has a built-in preamplifier that increases the detection output of each detection element. .

A data collection unit 7 that receives the output of the X-ray detector 6 includes:
Projection data based on the transmitted X-ray intensity detected by each detection element constituting the X-ray detector 6 is collected in all directions of the object 1 to be inspected, and the output of the preamplifier is integrated. It has a built-in integration circuit etc. The projection data obtained by the data collection section 7 is sent to the CPU 8.

The CPU 8 has an arithmetic circuit, a memory, a preprocessing function for performing correction calculations for adding various corrections such as offset correction to the projection data, and a specific cross section of the object 1 to be inspected according to a reconstruction algorithm. It has a reconstruction function that reconstructs a tomographic image based on the X-ray transmittance distribution.

The tomographic image reconstructed as described above by the CPU 8 is displayed on a CRT display 9 connected to the CPU 8. Further, the control console 10 connected to the CPU 8 controls the mechanism control section 11 or the X-ray control section 12 according to control commands from the CPU 8 or input information from the outside.
It is assumed that the controller has a function of outputting operation commands to the controller. The drive mechanism 2 is driven under the control of the mechanism control section 11 based on the command, and the XJ! 1liX4 is operated under the control of the X-ray control section 12 based on the command.

The pulse conversion unit 13 generates an X-ray generation pulse signal amount that instructs the emission timing of the X-ray beam 5 from the X-ray source 4 based on an encoder pulse P from a rotary encoder (not shown) provided in the drive mechanism 2; The data collection pulse signal N is used to direct the data collection operation timing in the data collection unit 7, and the amount of the X-ray generation pulse signal is directed to the X-ray control unit 12. They are each sent to section 7.

The configuration of the X-ray source 4, X-ray beam 5, X-ray detector 6, etc. and the positional relationship thereof in the embodiment will be explained with reference to FIGS. 2 and 3. The X-ray source 4 includes an accelerator (not shown) that accelerates an electron beam, a target 22 that is collided with the accelerated electron beam 21, and a slit 23 installed on the X-ray detector 6 side of this target. The X-rays generated at the target 22 are radiated toward the radiation detector side of the target 22 (hereinafter referred to as the front of the target), pass through the opening of the slit 23, and enter the X-ray detector 6. The slit 23 blocks X-rays emitted in a direction different from the front of the target 22, reduces background, and improves the S/N ratio.

Here, X,ill incident on the detection element 68 of a specific channel of the X-ray detector 6 is transmitted through the opening of the slit 23 to the target 2 which the detection element 6a faces.
2 specific portion 22a is generated. In this way, the detection elements of each channel constituting the X-ray detection device 6 have a corresponding specific portion of the target, and the X-ray detector 6 corresponds to the entire area of the target 22.

Therefore, even though a large target 22 is used, the X-ray generation source corresponding to the detection element of each channel can be regarded as a point, and a high-resolution tomographic image can be obtained. Moreover, in the X-ray source of the imaging device of the present invention, a large target is used as described above, and the accelerated electron beam is made to collide with the entire surface of the target. Large doses are possible without overheating problems.

As described above, since a substantially point-like and large-dose X-ray source is used, the imaging apparatus of the present invention improves the S/N ratio of X-ray projection data and reduces image noise. Therefore, a tomographic image with good image quality can be obtained.

Note that the present invention is not limited to the above embodiments.

That is, it is clear that the X@CT scanner described as an example can also be applied to a projection image imaging device using radiation.

[Effects of the Invention] As is clear from the above, according to the imaging device of the present invention, it is possible to obtain tomographic images and projection images with good image quality.
The accuracy of IP destructive inspection, diagnosis, etc. can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the overall configuration of one embodiment of the present invention, and FIG.
The figure is a schematic plan view showing the relationship between the X#I source and the X-ray beam in the embodiment, and FIG. 3 is a schematic side view showing the relationship between the Xm source and the X-ray beam. 1...Object to be inspected 2...Drive mechanism 3
...Turntable 4...X-ray source
5... X-ray beam 6... X-ray detection device 6a... Detection element 7. Old... Data collection section 8... CPtJ 9... ...CRT display frame 10, old control console section 11...
... Mechanism control section 12 ... X-ray control section 1
3...Pulse conversion fs M...xg
Generated pulse signal N... Data acquisition pulse signal P... Encoder pulse 21... Electron beam 22... Eye... Target 23... Slit

Claims (1)

[Claims] An X-ray source and an X-ray detection device disposed opposite to the X-ray source, which captures a projected image or a tomographic image of an object placed between the X-ray source and the X-ray source. A target that receives the impact of the accelerated electron beam is a concave disk-shaped target facing the object to be inspected, a slit is arranged between the target and the object to be inspected, and the X-ray detection device 1. An imaging device comprising a plurality of detection elements arranged on a circular arc centered on an aperture with a detection axis matching the diameter of the circular arc.