WO2004086017A1

WO2004086017A1 - X-ray imaging device

Info

Publication number: WO2004086017A1
Application number: PCT/JP2004/003743
Authority: WO
Inventors: Koichi Omori; Manabu Nishihara; Toshikazu Yoneda; Sueki Baba
Original assignee: Matsushita Electric Industrial Co. Ltd.
Priority date: 2003-03-26
Filing date: 2004-03-19
Publication date: 2004-10-07
Also published as: JP2004294182A; TW200504353A

Abstract

An X-ray imaging device comprising a full-frame transfer CCD sensor. The device comprises an X-ray generation unit for emitting an X-ray, a full-frame transfer CCD sensor (4) for receiving an X-ray emitted from the X-ray generation unit, and a shield material (3) disposed between the X-ray generation unit and the full-frame transfer CCD sensor (4), wherein an X-ray is beamed to or shut out from the full-frame transfer CCD sensor (4) by rotating/moving the shield material (3), and signals are stored when an X-ray is beamed to the full-frame transfer CCD sensor (4) and stored signal are transferred or output when it is shut out.

Description

Specification

X-ray imaging equipment

The present invention relates to an X-ray imaging apparatus that irradiates an object with X-rays and captures a fluoroscopic image thereof. Background art

2. Description of the Related Art In recent years, digital imaging systems using a two-dimensional X-ray imager as an X-ray imaging device have attracted attention in X-ray inspection apparatuses. The digital imaging method has a wide dynamic range of images, and can detect minute differences in the density of X-ray images that cannot be captured by conventional analog imaging methods. X-ray CCD sensors and X-ray flat panels that can detect X-rays are known as two-dimensional X-ray imagers for digital imaging. Above all, X-ray CCD has low noise level, so it is possible to take X-ray images with excellent S / N ratio. Such an X-ray inspection apparatus is disclosed in Japanese Patent Application Laid-Open No. 2001-165873.

CCDs (Charge Coupled Devices) include a full-frame transfer CC, a frame transfer CCD, and an interline transfer CCD. Among them, full-frame transfer CDs (hereinafter referred to as FFT-CCDs) are suitable for X-ray CCD sensors because of their easy detection of large elements and high detection sensitivity. Also, as the number of pixels of the X-ray imager increases, more precise image shooting becomes possible. In recent years, more than 1,000,000 pixels have been required. The FFT-CCD has a configuration in which the same element of a unit pixel has a storage function that replaces photons incident on the CCD with electric charges and stores them, and a transfer function that performs し / load. In the case where it is necessary to take an image in combination with the shading of the sun, or in the case of a shade, it is easy to block light such as visible light. However, since X-rays have penetrating power, they cannot be blocked by such shirts.

Therefore, it is necessary to use a material having a high density and a high X-ray shielding ability, such as lead-tungsten. However, opening and closing in a short period of time increases the mechanical load, so it was not possible to shoot a moving image that required continuous opening and closing of the shutter in a short period of time.

In addition, since the X-ray generator used in the X-ray inspection device has a weak X-ray output, the amount of X-ray incident on the CCD differs depending on the position of the shutter depending on the opening and closing of the shutter. As a result, there is also a disadvantage that even when irradiating a uniform amount of X-rays, an image with different brightness in the screen can be obtained.

For these reasons, an X-ray sensor using an FFT-CCD has the advantage of high sensitivity and low noise, but requires only a still image to be captured using a normal focus X-ray generator with high X-ray output. Not used only for dental intraoral radiographing device ゃ panoramic radiographing device. And it had a problem that it could not be used for X-ray inspection equipment for nondestructive inspection.

In addition, since FFT-CCD captures an image with one accumulation, the dynamic range of the image is limited by the saturation charge of CCD.

Increasing the resolution by reducing the pixel size of the CCD increases the saturation charge And the dynamic range was reduced. Therefore, as the number of CCD pixels is increased to capture a thin image, the transfer time of the load accumulated inside the CCD sensor increases as the number of pixels increases.

<The shooting cycle was long.

The present invention solves the above-mentioned conventional problems, and provides an X-ray inspection apparatus that can use FFT-CCD.

The present invention provides an X-ray generator that irradiates X-rays, a sensor that receives X-rays emitted from an mB3 X-ray generator, a controller that controls the sensor, the X-ray generator, and the sensor An X-ray inspection apparatus having a shielding unit for passing and shielding X-rays, wherein a full-frame transfer CCD is used as the sensor, and a rotating member is used as the shielding unit. An X-ray detection apparatus is provided, in which a portion for passing X-rays is provided in a part of the rotating member, the rotating member is rotated in one direction, and the full-frame transfer CCD allows X-rays to pass when charge is leaked. provide. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic diagram illustrating a configuration of an X-ray imaging apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a timing chart illustrating an operation method according to the first embodiment of the present invention.

FIG. 3 is an evening timing chart illustrating a method of operating the V 2> 3o (5th Embodiment 2). BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1)

The first embodiment will be described below with reference to FIGS.

Figure 1 shows an X-ray source 1, an X-ray exit 2, a shield 3 made of a fan-shaped metal plate, an FFT-CCD sensor 4, a motor 5 with a rotating shaft mounted at the center of the shield 3, and a position sensor 6, an FFT-CCD sensor controller 7, an X-ray controller 8, a personal computer (hereinafter referred to as a PC) 9, an object to be inspected 10, and a housing 11 are shown.

FIG. 2 is a timing chart illustrating the operation method. In FIG. 2, A is a moving image preparation command transmitted from the PC 9 to the controller 7, B is a moving image operation command transmitted from the PC 9 to the X-ray controller 8, and C is a controller from the PC 9 to the controller. 7 shows the motion stop command sent to 7, D shows the rotation operation status of the motor 5, E shows the shutter open signal sent from the position sensor 6, and F shows the transfer operation of the FFT-CCD sensor 4. . In the chart shown in D, the motor 5 rotates at the time of Hi.

The operation of the X-ray imaging device configured as described above will be described.

In the imaging device of the present embodiment, X-ray generation source 1 is provided in the direction of the upper inside surface of housing 12. X-ray source 1 is a microfocus X-ray tube with a focal size of 7 m, and the output is 10 W. Therefore, for example, when the X-ray tube voltage is 70 kV, only a tube current of 140 A can flow. I can't do that. With a normal focus X-ray with a focus size of 700 m, the tube current can flow up to about 8 mA, so that the intensity of the X-ray emitted from the X-ray exit 2 is lower than that of a normal focus X-ray. One order of magnitude lower. The X-ray controller 8 controls the X-ray source 1. X-ray controller 8 sends X-ray ON / OFF signals and X-ray control signals such as tube voltage and tube current commands to X-ray source 1. A shield 3 is provided at the X-ray exit 2 in the X-ray beam irradiation direction. The shielding body 3 is composed of a fan-shaped shielding portion 3A composed of a member mainly composed of stainless steel, and a fan-shaped X-ray passing portion 3B that has no shielding portion 3A and transmits X-rays. The shield 3 is moved in one direction by a motor 5, that is, the X-ray source

1 and rotates in a direction substantially perpendicular to the direction connecting the FFT-CCD sensor 4. When the shield 3A of the shield 3 covers the emission port 2, the X-ray beam is blocked. On the other hand, when the X-ray passing portion 3B is located on the exit side of the exit port 2, the X-ray beam is irradiated on the inspection object 10 and F F T—C

It enters the CD sensor 4. In this way, the shield 3 functions as an X-ray shutter. Tungsten constituting the shield 3 is a material having an atomic number of 74 and a density of 19.3, and has a high X-ray shielding ability but a high density and a heavy material. In this case, a high torque motor

By rotating in one direction by using 5, it is possible to open and close the shaft with small load movement. As such a motor 5, for example, a Suatsunog motor is used. The X-rays that have passed through the X-ray passing section 3B pass through the inspection object 10 and are transmitted through the FFT-CCD sensor.

On the other hand, the FFT-CCD sensor 4 is provided with a position sensor 6 for detecting the open / closed state of the shield 3, and a CCD controller 7 for controlling the operation thereof is connected to the shield 3. In addition, CCD controller 7 is connected to PC 9 for transmitting control commands. An X-ray control unit 8 is also connected to PC 9.

Hereinafter, a moving image capturing operation in the X-ray imaging apparatus of the present embodiment will be described.

The video capture preparation command A is sent from the PC 9 to the CCD controller 7, and the camera enters the image capture standby state. Subsequently, the video operation command B is sent to the X-ray controller 8. Upon receiving the operation command B, a rotation start instruction is transmitted to the motor 5 and the shield 3 starts rotating as shown in D. When the shield 3 starts rotating, the position sensor 6 detects the presence or absence of the shield 3A. In this embodiment, when the shielding portion 3A is not located at the position of the emission port 2 (when the X-ray passing portion 3B is located), the output of the position sensor 6 becomes Hi as shown in E. The output of the position sensor 6 is transmitted to the CCD controller 7, and when it is Hi, the FFT—CCD sensor 4 enters the accumulation period. Then, the X-rays incident on the FFT-CCD sensor 4 are converted into signal charges and stored in the pixels constituting the FFT-CCD sensor 4. When there is a shielding portion 3A at the position of the exit port 2, the output of the position sensor 6 becomes Low, and as shown in F, the FFT-CCD sensor 4 enters the readout period. Then, the signal charges accumulated in the FFT-CCD sensor 4 are transferred, an image signal is output from the FFT-CCD sensor 4, transferred to the PC 9 via the CCD controller 7, and an image is displayed. When the rotation of the shield 3 is continued, the cycle of accumulation and transfer is continuously repeated as shown by E and F, and a moving image is displayed on the screen of the PC 9. In addition, when the moving image operation stop command C is transmitted from the PC 9, the rotation is stopped and the imaging operation ends.

As described above, according to the present embodiment, by rotating the fan-shaped shield 3 made of tungsten with excellent shielding ability in one direction, FFT—X-rays incident on the CCD sensor 4 can be intermittently blocked. As a result, it is possible to read out the signal charges accumulated during X-ray cutoff and display an image of the accumulation of signal charges generated by X-ray detection and X-ray incidence during X-ray irradiation. That is, X-ray moving images can be captured using the FFT-CCD sensor 4. Also, during the rising period of photographing when the shield 3 starts rotating, the shielding time of the shield 3 differs in the plane of the FFT-CCD sensor 4 and the exposure time is microscopically different in the imaging plane of the CCD sensor 4. (Hereinafter, this phenomenon is called “keri” by shield. This is a Japanese word.) When the shield 3 reciprocates, a difference in the plane of the FFT-CCD sensor 4 during the exposure time due to the above-mentioned burr occurs in the same direction at the time of rising and falling, so that the difference of the exposure time is enlarged. Since the exposure time of one screen is short in moving image shooting, the difference in the exposure time deteriorates the image quality of the shot image. In the present invention, since the shield 3 rotates in the same direction, the FFT—Since the burr caused by the shield 3 of the X-ray amount incident on the CCD sensor 4 occurs in the rising and falling directions in the opposite direction, the FFT— Variations in the exposure amount of the CCD sensor 4 in the imaging plane are minimized during the reciprocating movement. Therefore, the exposure time per cycle is short, and a uniform X-ray image can be captured even in a moving image where the effect of the above-mentioned burr is large.

In this embodiment, the case where the X-ray generation source 1 is on the upper surface of the apparatus and the position of the FFT-CCD sensor 4 is on the lower surface of the apparatus has been described. However, the present invention is not limited to this, and it suffices that the X-ray source 1 and the FFT-CCD sensor 4 are located at positions facing each other.

Although the shield 3 is provided near the exit 2, the exit 2 and the FF Any location may be used as long as the shield 3 is located between the T-CCD sensor 4.

Further, the shield 3 is made of tungsten, but any structure including an element having a high shielding ability with an atomic number of 50 or more and a density of 3 or more such as lead, tin, iron, and copper can be used in the same manner. .

(Embodiment 2)

Hereinafter, the second embodiment will be described with reference to FIGS. Fig. 3 shows a still image capture preparation command A1 sent from the PC 9 to the CCD controller 7, a still image operation command B1 sent from the PC 9 to the X-ray controller 8, and a The operation command D 1 sent to the motor 5, the charge accumulation command E 1 sent to the CCD controller 7, the FFT—the transfer operation F 1 from the CCD sensor 4 to the PC 9, and the position sensor 6 are output FIG. 6 is a timing chart showing shutter opening signals G 1 respectively. The configuration of the device is the same as that of the first embodiment, and a detailed description thereof will be omitted.

The PC 9 sends the still image capture preparation command A1 to the CCD controller 7, and enters the image capture standby state. Subsequently, the still image operation command B 1 is sent to the X-ray controller 8. Upon receiving the odd-numbered operation command, a rotation start instruction is transmitted to the motor 5 and the shield 3 starts rotating and stops at the X-ray passage section 3B. Next, a command to rotate the motor 5 in the same direction is given by the even-numbered command, and the shield 3 stops at the position where the shielding unit 3 A is arranged at the emission port 2 of the X-ray generator 1.

The presence or absence of the shielding portion 3A is detected by the position sensor 6. In the present embodiment, when the shielding unit 3 is not provided (when the X-ray passing unit 3B is located at the exit port 2), the output of the position sensor 6 becomes Hi as shown by G1. You. The output of the position sensor 6 is transmitted to the CCD controller 7 and when Hi, the FFT-CCD sensor 4 enters the accumulation period, and the X-rays incident on the FFT-CCD sensor 4 are converted into signal charges, and the FFT-CCD sensor 4 Are accumulated in the pixels constituting When the blocking unit 3A is located at the emission port 2, the output of the position sensor 6 becomes Low, and the FFT-CCD sensor 4 enters the readout period as indicated by F1. The signal charge stored in the FFT-CCD sensor 4 is transferred, and an image signal is output from the FFT-single CCD sensor 4, transferred to the PC 9 via the CCD controller 7, and stored as image data. These operations are performed in multiple cycles, and the image data in each cycle is added, or the added data is divided according to the number of repetitions of the cycle, and stored in the storage of the PC 9 as a still image data. Is displayed on the screen. In the embodiment of the present invention, since the shield 3 rotates in the same direction, as in the first embodiment, the surface of the FFT-CCD sensor 4 due to the X-ray dose of the shield 3 that is incident on the FFT-CCD sensor 4 Inner variation is minimized when reciprocating. As a result, a uniform X-ray image can be captured even with the above-described low exposure time.

As described above, according to the present embodiment, the fan-shaped shield 3 made of evening stainless steel having excellent shielding ability is rotated in one direction, and the image is stored multiple times at the X-ray passing position and the image is stored at the shielding position. Repeat the transfer. By adding or averaging the image data sent to the PC 9, the image signal sent from the FFT-CCD sensor 4 can be accumulated to the saturation capacity of the FFT-CCD sensor 4 or more. Therefore, the dynamic range of the device is FFT—the saturation capacity of the CCD sensor 4, that is, the pixel It can be expanded regardless of the size and can take excellent SZN images. Also, by repeating the sampling of the image a plurality of times, the quantum noise of the image is reduced and a smooth image with less noise can be taken.

In the present embodiment, the X-ray source 1 is described as the upper surface of the apparatus, and the position of the FFT-CCD sensor 4 is described as the lower surface of the apparatus. However, the present invention is not limited to this. It suffices if the X-ray source 1 and the FFT-CCD sensor 4 are at opposing positions. Further, the shield 3 is provided close to the output port 2, but any location may be used as long as the shield 3 is located between the output port 2 and the FFT-CCD sensor 4.

In addition, the shield 3 is made of tungsten, but any structure may be used as long as the structure includes an element having an atomic number of 50 or more and a high density of 3 or more such as lead, tin, iron, and copper.

As is clear from the above description, the use of the X-ray imaging apparatus of the present invention makes it possible to take an X-ray moving image with an FFT-CCD sensor having high sensitivity and low noise. Further, the image signal can be stored without being restricted by the saturation capacity due to the pixel size of the FFT-CCD sensor. As a result, an X-ray image with a wide dynamic range can be taken, and quantum variations in the image can be suppressed, and a smooth image can be taken.

It should be noted that, depending on the required image details, it is possible to switch between adding the output signals of a plurality of pixels constituting FFT—CCD.

The present invention can provide an X-ray imaging apparatus capable of expanding the dynamic range regardless of the saturation capacity of the FFT-CCD sensor 4, that is, regardless of the pixel size, and capturing an image with an excellent SZN ratio.

Claims

The scope of the claims

1. An X-ray generator that irradiates X-rays, a sensor that receives the X-rays emitted from the X-ray generator, a controller that controls the sensor, and a sensor between the X-ray generator and the sensor. It is equipped with a shielding part that arranges and transmits and shields X-rays, and full-frame transfer is used as the sensor.

Using a CCD, using a rotating member as the shielding part, providing a passing part for passing X-rays in a part of the rotating member, rotating the rotating member in one direction, and providing the full frame transfer CCD. An X-ray imaging device that allows X-rays to pass during charge storage.

2. Charges are accumulated in the full-frame transfer CCD when the shielding unit passes through the X-rays, and charges accumulated in the full-frame transfer CCD are transferred when the X-rays are shielded by the shielding unit to output an image signal. 2. The X-ray imaging apparatus according to claim 1, wherein the moving image is formed by repeating the X-ray passage and the X-ray shielding a plurality of times.

3. Charge is accumulated in the full frame transfer CCD at the time of X-ray passage by the shielding unit, and is transferred when the X-ray is shielded by the shielding unit. 2. The X-ray imaging apparatus according to claim 1, wherein the X-ray imaging apparatus obtains an image by repeating the X-ray passage and the X-ray shielding a plurality of times, and adding or averaging the plurality of output image signals.

4. The driving unit for rotating the rotating member is provided, a position detector for detecting a position of the rotating member is provided, and the full frame transfer CCD is controlled based on a signal from the position detector. X-ray imaging device.

5. A driving unit for rotating the rotating member is provided, and the full frame is provided. The X-ray imaging apparatus according to claim 1, wherein the drive unit is controlled based on a signal from a memory transfer CCD or the control unit.

6. The X-ray imaging apparatus according to claim 1, wherein the rotating member has a fan-shaped shielding part and a fan-shaped passing part.

7. The X-ray imaging apparatus according to claim 6, wherein a rotation direction of the rotating member is substantially perpendicular to a direction connecting the X-ray generation unit and the full frame transfer CCD.

8. The X-ray imaging apparatus according to claim 6, wherein the rotating member includes at least one element of lead, tungsten, tin, iron, and copper.

9. The X-ray imaging apparatus according to claim 5, wherein a stepping motor is used for the driving unit.

10. The X-ray imaging apparatus according to claim 1, wherein output signals of a plurality of pixels constituting the full frame transfer CCD are added.

11. The X-ray imaging apparatus according to claim 10, wherein the addition of the output signals of the plurality of pixels constituting the full frame transfer CCD is switched depending on the required image detail.