JP2015141142A - Transmission image pickup system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large-screen semiconductor detector capable of quickly picking up a transmission image by imaging an entire imaging sample at one time even if the imaging sample is a large-sized metallic structure.SOLUTION: A partial module 100 that constitutes a semiconductor detector includes detection elements 1 each generating a current in response to an incident X-ray; detection element substrates 2 each disposed in rear of the detection elements 1, elongated in the same direction as an X-ray radiation direction, and having the detection elements 1 disposed on both surfaces thereof; a circuit board 3 to which the plurality of detection element substrates 2 is coupled by a coupling member; and signal processing circuits 6 disposed on both surfaces of the circuit board 3 and coupled to wiring boards 5 withdrawn from the detection element substrates 2. A combination of a plurality of partial modules 100 constitute the semiconductor detector.

Description

  The present invention relates to a transmission image capturing system.

  X-ray transmission imaging has been widely used in the medical field for a long time. However, in the industrial field, it is possible to detect nondestructive defects inside the target equipment. Has been used for internal inspection. In these transmission imaging, an X-ray photosensitive film has usually been used as an X-ray detection device after passing through a subject. On the other hand, in recent years, devices capable of measuring the transmitted X-ray dose after passing through the subject as a digital value such as an imaging plate (IP), a flat panel detector (FPD), and a semiconductor detector have been developed and spread as X-ray detection devices. ing.

  The imaging plate (IP) is a film coated with stimulable phosphor (BaFBr: Eu2 +) microcrystals. When the surface of the film is irradiated with a laser beam by X-rays, light is emitted according to the exposure amount of the X-rays. Therefore, an X-ray transmission image proportional to the X-ray irradiation can be obtained by measuring the light emission amount with a digital value. Therefore, the IP main body does not require a signal processing circuit for measuring the radiation dose, and the signal processing circuit is incorporated in the light emission amount reading device.

  A flat panel detector (FPD) emits light with a thin film scintillator (CsI) by incident X-rays, and measures the amount of light emitted by converting it into charges with a photodiode to obtain an X-ray transmission image. The signal processing circuit exists behind the scintillator.

  Si, CdTe, etc. have been put to practical use as semiconductor detectors. Unlike medical use, X-ray transmission image apparatuses for industrial use often have a metal object as the object, and require X-ray energy having a strong transmission ability as compared with human use. The semiconductor detector is highly sensitive to high energy X-rays. Therefore, in industrial transmission image capturing, when the target object is a large metal structure, it is more effective than IP or FPD, and a higher-quality transmission image can be obtained. In addition, the Si semiconductor detector is highly effective for high energy X-rays in industrial high energy X-ray CT apparatuses.

  In the example shown in Japanese Patent Laid-Open No. 2012-83277, the X-ray light receiving portion made of a semiconductor is separated for each single detector and has a structure independent of adjacent channels including the FPC board. In addition, each detector is arranged at regular intervals in one direction to constitute a one-dimensional line sensor. In these detector array configurations, the signal processing circuit digitizes the current value due to the charges generated when the X-rays enter the detector. The signal processing circuit is behind the detector and is provided on one substrate for each detection element. Further, the signal processing circuit is mounted on a large substrate, and is connected to the line sensor by a wiring cable, and the line sensor and the signal processing circuit are separated by a certain distance.

JP 2012-83277 JP

  In X-ray transmission imaging in the industrial field, there are vehicle structures and steam turbines as imaging objects, and large metal structures may be imaging objects. Conventionally, in transmission image capturing for these large metal structures, partial region imaging is repeated, or an object is disassembled or cut to reduce the size. On the other hand, when the deformation state of the large subject is sequentially captured as a transmission image, it is necessary to image the entire large subject at a time because the entire image cannot be captured by the partial region imaging. In order to solve these requirements, a detector having a large screen that can fit the entire large subject in the field of view of imaging is required.

  Furthermore, in order to construct a detector with a large screen, it is necessary to install a signal processing circuit in a compact manner behind the detector. In the conventional signal processing circuit mounting method, the circuit mounting portion does not fit only in the space behind the detector element array, and the circuit is arranged in a wider space in the vertical and horizontal directions than the detection element surface.

  On the other hand, in order to construct a large screen, it is necessary to arrange a plurality of detector modules, and the circuit mounting portion that processes one detector module has the same size as the detection surface of the detector module, and the detection element. If it is not installed behind the large screen, it cannot be configured.

  The detector screen size of the aforementioned imaging plate (IP) and flat panel detector (FPD) is about 400 mm x 400 mm at the maximum due to restrictions on the manufacturing and manufacturing of the detector elements, and it is difficult to increase the size beyond that size. .

  In addition, in the transmission imaging of large metal structures, it is necessary to use a high-energy X-ray source with high transmission capability, and both the imaging plate (IP) and flat panel detector (FPD) use the energy of the X-ray source. As a level, ˜200 kV is an applicable range with significant sensitivity. This is because when the sensitivity of the detection element to X-ray energy exceeds 200 kV, it rapidly decreases. When using linear accelerators that allow X-ray energy levels in the MV range to penetrate industrial thick metal, imaging plates (IP) and flat panel detectors (FPDs) use high energy X-rays in the MV range. Since the sensitivity to is very low, a sufficient image cannot be obtained.

  In the semiconductor detector having high sensitivity to the above-mentioned X-rays in the high energy region, it is mainly used in a single line sensor, and there are only a few configuration examples of the detection surface as a two-dimensional plane. . CdTe detectors in practical use have a maximum detection surface size of about 50 mm × 50 mm, and it is difficult to increase the size of the current structure due to restrictions in manufacturing and manufacturing of detection elements, as in FPD.

  In addition, in order to obtain a transmission image by using a one-dimensional line sensor based on an Si semiconductor detector used in the industrial high energy X-ray CT apparatus described in the background art, the one-dimensional line sensor is referred to as the sensor arrangement direction. It is necessary to scan in the vertical direction and take an image. For this reason, when the subject becomes large, it takes time to scan in order to capture a transmission image of the entire subject, and it is difficult to obtain a transmission image continuously in a short time.

Therefore, the object of the present invention is made in the background as described above, and in a transmission image imaging system using an industrial high-energy X-ray source, the imaging subject is a large metal structure. The present invention also provides a large-screen semiconductor detector capable of rapidly capturing a transmission image of a whole subject with a single imaging.

  The partial module constituting the semiconductor detector of the present invention includes a detection element that generates current by incident X-rays, a detection element substrate that is longer in the X-ray incidence direction than the detection elements and that has detection elements disposed on both sides, A circuit board in which the detection element board is connected by a connecting member, and a signal processing circuit connected to a wiring board drawn from the detection element board on both sides of the circuit board, and semiconductor detection by combining multiple partial modules It constitutes a container.

According to the present invention, in a transmission image imaging system using an industrial high-energy X-ray source, even when the imaging subject is a large metal structure, the entire subject can be quickly transmitted by one imaging. Can be provided.

It is a figure showing an example of the circuit mounting structure for dense detectors which are one Example of this invention. It is a figure showing the basic composition of the signal processing circuit built in with the circuit mounting structure for dense detectors which is one example of the present invention. It is the figure showing the bird's-eye view of one detector module using the circuit mounting structure for dense detectors which is one Example of this invention. It is the figure which showed one part of the large screen detector which arranged and comprised two or more detector modules using the circuit mounting structure for dense detectors which is one Example of this invention. It is the figure which showed the whole image of the big screen detector which arranged and comprised two or more detector modules using the circuit mounting structure for dense detectors which is one Example of this invention. It is a figure showing the arrangement arrangement | positioning apparatus of the X-ray transmission image system using the large screen detector which arranged and comprised two or more detector modules using the circuit mounting structure for dense detectors which is one Example of this invention. .

  The present invention uses a X-ray to measure the amount of X-ray transmitted through the subject, thereby detecting the external shape and the internal shape of the subject in a nondestructive manner. It is related with the mounting technology of the signal processing circuit.

  Hereinafter, embodiments of the present invention will be described with reference to a configuration diagram of a detector.

  1 (a) and 1 (b) show the structure related to the partial module of the detector. The detection element 1 that generates a current by incident X-rays has a plurality of electrode configurations at constant intervals in a semiconductor having a constant thickness such as Si or CdTe. The detection element 1 is installed on the detection element substrate 2. The detection element substrate 2 extends in the depth direction (Z direction, that is, the X-ray incidence direction) more than the detection element 1, and is connected to the circuit board 3 via the connection member 4.

  Each detection element 1 is connected to the signal processing circuit 6 by a wiring cable on the detection element substrate 2 and the wiring board 5. The basic configuration of the signal processing circuit 6 is shown in FIG. The signal processing circuit 6 includes a first-stage amplifier circuit 7, a sample hold (S / H) circuit 8, an AD converter 9, a memory 10, and an external interface 11 for one detection element 1. In this embodiment, as shown in FIG. 1B, a plurality of detection elements 1 are installed on one detection element substrate 2, and a plurality of detection elements 1 on the one detection element substrate 2 are provided. The signal processing of FIG. 2 is integrated in the signal processing circuit 6.

  As shown in FIG. 1 (a), each detection element substrate 2 has an array of detection elements 1 on both the front and back surfaces of the tip. For this reason, the signal processing circuit 6 performs signal processing corresponding to the number of detector elements 1 arranged on the front surface of each detector element substrate 2 and the sum of the number of detector elements 1 arranged on the back side. Executed. In the embodiment shown in FIG. 1, four detection element substrates 2 are connected to one circuit substrate 3 via a connecting member 4 and connected to four signal processing circuits 6 via a wiring board 5. . In this embodiment, one signal processing circuit 6 is connected from one detection element substrate 2, but a plurality of detection element substrates 2 are connected to one signal processing circuit 6 by the processing capability of the signal processing circuit. Things are also possible.

  In addition, the signal processing circuits 6 installed on both surfaces of the circuit board 3 are arranged so as to be shifted in the front-rear direction (Z direction) of the circuit board 3, compared with the case where the circuit boards 3 are stacked vertically (X direction). Thus, the height of the partial module 100 of the detector is reduced.

  3 (a) (b), FIG. 4 (a) (b) and FIG. 5 (a) (b) () show the configuration of a large-screen semiconductor detector in a transmission image capturing system using the circuit mounting structure of the present invention. Shown in c). FIG. 6 shows a high energy transmission image system configuration using a large screen detector using the circuit mounting structure of this embodiment as a component.

  FIG. 3A shows the detector module 12 using the circuit mounting structure of this embodiment. A plurality of detection element substrates 2 shown in FIG. 3B are connected to each other to constitute the partial module 100 shown in FIGS. Specifically, in the partial module 100 shown in FIGS. 1A and 1B, four detection element substrates 2 are connected by a connecting member 4. Further, the detector module 12 of FIG. 3A is configured by combining a plurality of the partial modules 100. The circuit mounting portion of the present embodiment is disposed behind the detector module 12 in FIG.

  As shown in FIGS. 4 (a) and 4 (b), a plurality of detector modules 12 using the circuit mounting structure of this embodiment are arranged in a fixed arrangement and integrated to form a large screen. The plurality of detector modules 12 are held by a frame 14 for constituting a large screen. Further, as shown in FIG. 4 (a), the X-ray incident surface of the detector module 12 is located with respect to the center of the X-ray source so that the X-ray receiving surface of each detector module captures the center of the X-ray source. Thus, the tangent plane at the center of the surface is arranged so as to be perpendicular to the center of the X-ray source.

  FIG. 5 shows the structure of the entire detector that has a large screen. The large-screen semiconductor detector 15 composed of a dense detector using the circuit mounting structure of the present embodiment includes a component 18 that supports the entire large screen composed of a plurality of detector modules 12, a support portion 16, and a pedestal 17. Consists of

A configuration example of a transmission image capturing system using the large-screen semiconductor detector having the configuration shown in FIGS. 1 to 5 is shown in FIG. In the system, the large-screen semiconductor detector 15 using the circuit mounting structure according to the present embodiment and the high energy X-ray source 19 are opposed to each other with the subject region 20 to be imaged. By combining the high-energy X-ray source 19 having a high transmission capability and the large-screen semiconductor detector 15 having a large light receiving area, even when the imaging subject is a large metal structure, the entire subject can be quickly captured by one imaging. It is possible to capture a transmission image. The X-ray transmission amount of each element measured by the large-screen semiconductor detector 15 is transmitted to the imaging processing unit 22 and imaged. Thereafter, the image is stored as a digital image in the storage device 23.

By using the circuit mounting structure for a dense detector according to the present invention, it is possible to configure a large-screen detector composed of dense detecting elements. As a result, in a transmission image imaging system using an industrial high energy X-ray source, even when the imaging subject is a large metal structure, the entire subject is quickly imaged with a single imaging. Things will be possible.

DESCRIPTION OF SYMBOLS 1 Detection element 2 Detector element board | substrate 3 Circuit board 4 Connecting member 5 Wiring board 6 Signal processing circuit 7 First stage amplifier circuit 8 Sample hold circuit 9 AD converter 10 Memory 11 External interface 12 Detector module 14 Frame 15 Large screen semiconductor detector 16 Support unit 17 Base 100 Partial module

Claims (3)

A transmission imaging system in which a semiconductor detector and a high-energy X-ray source are arranged relative to each other with an object to be imaged interposed therebetween,
The partial module constituting the semiconductor detector includes a detection element that generates an electric current by incident X-rays, and is elongated behind the detector element in the same direction as the X-ray irradiation direction, and the detection elements are arranged on both sides. A detection element substrate, a circuit board in which the plurality of detection element substrates are connected by a connecting member, and a signal processing circuit connected to a wiring board drawn from the detection element substrate on both surfaces of the circuit board,
A transmission image imaging system comprising the semiconductor detector by combining a plurality of the partial modules.
The transmission image capturing system according to claim 1,
A transmission image imaging system comprising: an imaging processing unit that images the X-ray transmission amount of each detection element output from the semiconductor detector; and a storage device that stores the imaged digital image.
The transmission image capturing system according to claim 1,
The transmission image capturing system, wherein the signal processing circuits installed on both surfaces of the circuit board are arranged to be shifted in the X-ray incident direction of the circuit board.