JP5638914B2 - Radiation imaging device - Google Patents

Description

  The present invention relates to a radiation imaging apparatus that performs imaging by irradiating a subject with radiation.

  In X-ray imaging, a subject is irradiated with X-rays, the X-rays that have passed through the subject are converted into visible light by a scintillator, and then the visible light reaches the image sensor. An X-ray image corresponding to the subject can be obtained by performing signal processing on the output of the image sensor.

  In the scintillator, it is known that the light emission efficiency on the X-ray incident surface is higher than the light emission efficiency on the X-ray emission surface. The X-ray emission surface is an emission surface when X-rays pass through the scintillator. Here, when the scintillator and the image sensor are arranged side by side in the X-ray traveling direction, the visible light generated on the X-ray exit surface of the scintillator reaches the image sensor. As a result, the resolution and contrast of the image obtained from the output of the image sensor may be insufficient.

A radiation imaging apparatus according to the present invention includes a reading unit that moves in one direction with respect to a subject irradiated with radiation and acquires a radiation image corresponding to the subject, and an actuator that drives the reading unit. . Here, the reading unit includes a scintillator that converts radiation into visible light, a line sensor that receives visible light emitted from the radiation incident surface of the scintillator and converts it into an electrical signal, and visible light emitted from the incident surface of the scintillator. And a reflecting member made of a prism .

  The light receiving surface of the line sensor can be directed in a direction different from the side irradiated with radiation. Thereby, it can suppress that a radiation injects into the light-receiving surface of a line sensor. And it can suppress that the noise by radiation is contained in the output signal of a line sensor, or can suppress degradation of the line sensor by radiation. For example, the light receiving surface of the line sensor can be directed in the moving direction of the reading unit.

More and this providing a reflection member for reflecting the visible light emitted from the incident surface of the scintillator to the line sensor, the visible light emitted from the incident surface of the scintillator, it is possible to easily reach the light receiving surface of the line sensor . For example, with one face of the prism, it can be reflected toward the visible light to the line sensor.

A case that covers the scintillator , the line sensor, and the reflecting member can be provided. Here, a case can be comprised by the 1st area | region which lets a radiation pass, and the 2nd area | region which blocks passage of a radiation.

  According to the present invention, since the visible light generated on the radiation incident surface of the scintillator is guided to the line sensor, the image quality of the radiation image obtained from the output of the line sensor can be improved.

1 is a schematic diagram illustrating an X-ray imaging system in Embodiment 1. FIG. 3 is a cross-sectional view of a reading unit in the X-ray imaging apparatus of Embodiment 1. FIG. It is a figure explaining the light emission effect | action of a scintillator. 6 is a cross-sectional view of a reading unit in an X-ray imaging apparatus according to Embodiment 2. FIG.

  Examples of the present invention will be described below.

  An X-ray imaging apparatus (corresponding to a radiation imaging apparatus) that is Embodiment 1 of the present invention will be described. FIG. 1 is a schematic diagram of an X-ray imaging system including the X-ray imaging apparatus of the present embodiment.

  The X-ray imaging system 1 includes an X-ray irradiation device 10 and an X-ray imaging device 20. The X-ray irradiation apparatus 10 emits X-rays within a predetermined irradiation range W, and the X-rays emitted from the X-ray irradiation apparatus 10 pass through the subject 30 and reach the X-ray imaging apparatus 20. The X-ray imaging apparatus 20 receives an X-ray transmitted through the subject 30 and performs an imaging operation. The X-ray irradiation apparatus 10 and the X-ray imaging apparatus 20 are arranged so as to sandwich the subject 30.

  The X-ray imaging system 1 can be used in medical diagnosis, industrial nondestructive inspection, and the like. That is, examples of the subject 30 include subjects such as animals such as humans and nondestructive inspection targets such as the internal structure of buildings.

  The X-ray imaging apparatus 20 includes a case 21 and a reading unit 40 disposed inside the case 21. The reading unit 40 moves in the direction of arrow D in the movement range L by receiving the driving force from the actuator 50. The case 21 supports the reading unit 40 in a movable state. The reading unit 40 extends in a direction orthogonal to the paper surface of FIG.

  Next, the structure of the reading unit 40 will be described with reference to FIG. FIG. 2 is a cross-sectional view of the reading unit 40 taken along a plane orthogonal to the longitudinal direction of the reading unit 40.

  The reading unit 40 has a case 41, and the case 41 is provided with an opening 41a for allowing X-rays to pass therethrough. The case 41 is made of a material that does not allow X-rays to pass therethrough, and the X-rays pass only through the openings 41a. For example, if the case 41 is formed of lead or the like, it is possible to prevent X-rays from passing through the case 41. Examples of the material forming the case 41 include iron, stainless steel, copper, tungsten, and barium in addition to lead.

  A prism 42 is disposed inside the case 41, and the prism 42 has three surfaces 42a to 42c. The three surfaces 42a to 42c extend in a direction orthogonal to the paper surface of FIG. The prism 42 only needs to be able to transmit visible light and X-rays, and can be formed of, for example, acrylic, glass, polyethylene terephthalate, or polycarbonate.

  A scintillator 43 is fixed to the first surface 42 a of the prism 42. The scintillator 43 converts X-rays into visible light, and is used as a radiation detector. Since the configuration of the scintillator 43 is known, detailed description thereof is omitted.

  The second surface 42b of the prism 42 is inclined with respect to the moving direction of the reading unit 40 (left-right direction in FIG. 2) and is inclined with respect to the first surface 42a and the third surface 42c. The third surface 42c of the prism 42 is a surface orthogonal to the moving direction of the reading unit 40, and the line sensor 44 is fixed to the third surface 42c.

  The line sensor 44 includes a lens array having a cylindrical lens (referred to as a lens unit) 44a that is long in a direction orthogonal to the paper surface of FIG. 2 and a plurality of image sensors 44b. The lens unit 44a is arranged in the longitudinal direction of the reading unit 40 (direction perpendicular to the paper surface of FIG. 2), thereby forming a lens array. The plurality of imaging elements 44b are provided with a length corresponding to the lens portion 44a. The lens portion 44a has an incident surface formed in a convex shape and an exit surface formed in a substantially flat surface. As the imaging device 44b, for example, a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) can be used.

  Next, the operation of the reading unit 40 will be described.

  The X-rays irradiated from the X-ray irradiation apparatus 10 pass through the subject 30 and reach the X-ray imaging apparatus 20. Here, the X-rays pass through the opening 41 a of the case 41 and enter the reading unit 40. X-rays pass through the prism 42 and reach the scintillator 43. In FIG. 2, an arrow indicated by a solid line indicates an X-ray traveling direction (an example).

  The scintillator 43 emits visible light by converting X-rays into visible light. Specifically, visible light is generated on the surface of the scintillator 43 in contact with the first surface 42a of the prism 42, in other words, on the surface of the scintillator 43 on which X-rays are incident. The amount of visible light generated by the scintillator 43 varies depending on the intensity of the X-rays that reach the scintillator 43. Here, the visible light generated by the scintillator 43 enters the prism 42. Visible light incident on the prism 42 is reflected by the second surface 42 b of the prism 42 and travels toward the line sensor 44. In FIG. 2, the arrow shown with a dotted line has shown the advancing direction (an example) of visible light.

  The lens unit 44a of the line sensor 44 collects visible light from the second surface 42b of the prism 42 toward the image sensor 44b. The imaging element 44b receives visible light transmitted through the lens unit 44a and converts it into an electrical signal. Thereby, an image corresponding to the intensity distribution of the X-rays that have passed through the subject 30 can be acquired. This image is an image for one line when an image showing the entire subject 30 is divided into a plurality of parts in the moving direction D of the reading unit 40 (see FIG. 1).

  If the line sensor 44 acquires an image each time the reading unit 40 moves in the movement direction D by a predetermined amount, an image showing the entire subject 30 can be obtained. That is, if an image for one line is connected, an image showing the entire subject 30 can be obtained.

  According to the present embodiment, visible light is generated on the surface of the scintillator 43 on which X-rays are incident, and the visible light is guided to the line sensor 44. Therefore, visible light having a light emission amount corresponding to the intensity of the X-rays is generated. can get. The X-ray incident surface of the scintillator 43 has higher visible light emission efficiency than the X-ray emission surface of the scintillator 43.

  Specifically, as shown in FIG. 3, when X-rays are irradiated to the scintillator 43, X-rays enter the surface (incident surface) 43 a of the scintillator 43, and from the surface (exit surface) 43 b of the scintillator 43. Assume that X-rays are emitted. At this time, the luminous efficiency at the incident surface 43a is higher than the luminous efficiency at the exit surface 43b. Therefore, by guiding the visible light generated on the X-ray incident surface to the line sensor 44, the image quality (specifically, resolution and contrast) of the image obtained from the output of the line sensor 44 can be improved. .

  In the present embodiment, the line sensor 44 is provided at a position deviated from the optical path of the X-ray, so that it is possible to prevent the X-ray from reaching the line sensor 44. In other words, the light receiving surface of the line sensor 44 (imaging device 44b) faces a direction different from the side irradiated with the X-rays, so that the X-rays can be prevented from reaching the line sensor 44.

  In this embodiment, the light receiving surface of the line sensor 44 faces the moving direction of the reading unit 40. The light receiving surface of the line sensor 44 may face a direction different from the moving direction of the reading unit 40. That is, it is only necessary that the light receiving surface of the line sensor 44 is directed in a direction different from the side irradiated with X-rays.

  As a result, it is possible to prevent X-rays from reaching the image sensor 44b and including noise in the output of the image sensor 44b. In addition, it is possible to prevent the image pickup element 44b from being deteriorated by X-rays.

  The reading unit 40 described in the present embodiment has the structure shown in FIG. 2, but is not limited thereto. That is, any configuration may be used as long as the scintillator 43 is disposed on the optical path of the X-ray and visible light generated by the scintillator 43 is reflected and guided to the line sensor 44.

  In this embodiment, the visible light is reflected by the second surface 42b of the prism 42 and guided to the line sensor 44. However, the visible light can be reflected by a plurality of surfaces and then can reach the line sensor 44. . Thereby, the freedom degree of arrangement | positioning of the line sensor 44 can be improved.

  In this embodiment, the case 41 for blocking the passage of X-rays is used, but the present invention is not limited to this. The arrival of X-rays to the line sensor 44 is not preferable in terms of noise generation and deterioration of the image sensor 44b as described above. Therefore, a case for blocking the passage of X-rays can be provided at a position surrounding the line sensor 44. In this case, it is necessary to arrange the case so as to avoid the optical path of visible light toward the image sensor 44b.

  In this embodiment, the prism 42 is used, but the present invention is not limited to this. That is, it is only necessary that the visible light generated by the scintillator 43 can be reflected and guided to the line sensor 44. Specifically, a mirror member (corresponding to a reflecting member) may be provided only at a position corresponding to the second surface 42b of the prism 42. In this case, the scintillator 43 and the line sensor 44 may be fixed to the inner wall surface of the case 41.

  An X-ray imaging apparatus that is Embodiment 2 of the present invention will be described. FIG. 4 is a cross-sectional view of a reading unit used in the X-ray imaging apparatus of this embodiment. In this embodiment, the structure of the reading unit is different from that of the first embodiment.

  In the first embodiment, the visible light generated by the scintillator 43 is reflected to reach the line sensor 44. In this embodiment, the visible light generated by the scintillator is allowed to reach the line sensor directly. Hereinafter, differences from the first embodiment will be mainly described.

  An opening 61 a is provided in the case 61 of the reading unit 60, and X-rays pass only through the opening 61 a and enter the inside of the case 61. A prism 62 is provided inside the case 61, and X-rays that have passed through the opening 61 a enter the first surface 62 a of the prism 62. The X-rays that have passed through the prism 62 reach the scintillator 63 provided on the second surface 62 b of the prism 62. In FIG. 4, an arrow indicated by a solid line indicates an X-ray traveling direction (an example).

  The surface of the scintillator 63 that contacts the second surface 62b is a surface on which X-rays enter. On the X-ray incident surface of the scintillator 63, the X-rays are converted into visible light, and the visible light passes through the prism 63 and travels toward the line sensor 64. Here, the X-ray incident surface of the scintillator 63 and the light receiving surface of the line sensor 64 (imaging device 64b) face each other in the left-right direction of FIG. 4 (in other words, the moving direction of the reading unit 60). For this reason, the visible light generated by the scintillator 63 is directed to the line sensor 64. The line sensor 64 is fixed to the third surface 62 c of the prism 62.

  The visible light emitted from the third surface 62c of the prism 62 is collected by the lens 64a and then reaches the image sensor 64b. The imaging element 64b generates an electrical signal corresponding to the amount of received light by photoelectrically converting visible light. The output signal of the image sensor 64b is subjected to predetermined signal processing to form an image.

  Also in this embodiment, since the X-ray does not reach the line sensor 64 directly, it is possible to prevent the X-ray from containing noise in the output of the line sensor 64 or the line sensor 64 from being deteriorated by the X-ray. can do. That is, since the light receiving surface of the line sensor 64 faces in a direction different from the X-ray irradiation side, the X-ray can be prevented from reaching the light receiving surface of the line sensor 64.

  In addition, since the scintillator 63 generates visible light on the surface on which X-rays are incident, it can efficiently generate visible light according to the intensity of the X-rays that reach the scintillator 63. Thereby, the resolution and contrast of the image generated based on the output of the line sensor 64 can be improved.

  In this embodiment, the case 61 that does not allow X-rays to pass covers the prism 62 and the line sensor 64, but the present invention is not limited to this. That is, any configuration may be used as long as the X-rays do not reach the line sensor 64. For example, only the line sensor 64 can be covered with a case that blocks the passage of X-rays.

  The position where the line sensor 64 is arranged can be set as appropriate. That is, it is only necessary that the visible light generated by the scintillator 63 can directly enter the line sensor 64. For example, the line sensor 64 can be disposed along the first surface 62 a of the prism 62. The position of the line sensor 64 can be set by changing the inclination angle of the scintillator 63 (in other words, the second surface 62b of the prism 62).

  In this embodiment, the prism 62 is used, but the present invention is not limited to this. That is, it is only necessary that the visible light generated by the scintillator 63 can be directly incident on the line sensor 64. For example, the prism 62 can be omitted. In this case, the scintillator 63 and the line sensor 64 may be fixed to the inner wall surface of the case 61.

1: X-ray imaging system 10: X-ray irradiation device 20: X-ray imaging device (radiation imaging device) 21: Case 30: Subject 40, 60: Reading unit 41, 61: Case 41a, 61a: Opening 42, 62: Prism 42a, 62a: 1st surface 42b, 62b: 2nd surface 42c, 62c: 3rd surface 43, 63: Scintillator 44, 64: Line sensor 44a, 64a: Lens part 44b, 64b: Image pick-up element 50: Actuator

Claims (4)

A reading unit for moving in one direction with respect to a subject irradiated with radiation and acquiring a radiation image corresponding to the subject;
An actuator for driving the reading unit,
The reading unit is
A scintillator that converts radiation into visible light;
A line sensor that receives visible light emitted from an incident surface of radiation in the scintillator and converts it into an electrical signal;
Reflecting visible light emitted from the incident surface of the scintillator toward the line sensor, and a reflecting member configured by a prism;
A radiation imaging apparatus comprising:   The radiation imaging apparatus according to claim 1, wherein a light receiving surface of the line sensor faces a direction different from a side irradiated with radiation.   The radiation imaging apparatus according to claim 2, wherein a light receiving surface of the line sensor faces a moving direction of the reading unit. It has a case that covers the scintillator , the line sensor, and the reflecting member ,
The case includes a first area for passing radiation, the radiation imaging apparatus according to claim 1, any one of 3, characterized in that a second region for blocking the passage of radiation.

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