JP2001198116A - X-ray imaging equipment - Google Patents

Abstract

(57) [Summary] An X-ray imaging apparatus is provided with a mechanism for attaching / detaching a grid for removing scattered X-rays. SOLUTION: This portable X-ray detection unit 31 is composed of an upper housing 32 and a lower housing 33, and a joint between the lower housing 33 and the upper housing 32 is light-tight. In order to insert the grid 34 into the upper housing 32 on the side surface of the upper housing 32,
A slit-shaped opening 32 a whose thickness and width are slightly larger than the grid 34 is provided. A support plate 35 is provided on the lower housing 33, and an X-ray detection sensor 36 is mounted on the support plate 35. The grid 34 can be completely pulled out of the upper housing 32, and when completely inserted, can cover the entire image area of the X-ray detection sensor 36. Between the front surface 36a of the X-ray detection sensor 36 and the back surface 32a of the upper housing 32 facing the front surface 36a, a space 37 having substantially the same interval as the thickness of the grid 34 is provided. can do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray imaging apparatus having a mechanism for attaching and detaching a grid used for removing scattered X-rays.

[0002]

2. Description of the Related Art Conventionally, the most common radiography method for X-ray photography is a film / screen method, in which a sheet of a rare earth phosphor which emits light when irradiated with X-rays is adhered to both surfaces of a photosensitive film. The camera is used for shooting. The X-rays transmitted through the subject are captured by the photosensitive film after being converted into visible light by the phosphor, and the image can be visualized by developing the photosensitive film.

As a second photographing method, a method called a computed radiography (CR) method has been put to practical use. In this method, a transmitted image of radiation is temporarily stored in a phosphor as a latent image, and the latent image is read out by irradiating excitation light later. For example, some phosphors have X
When radiation such as rays, α-rays, β-rays, γ-rays, electron beams, and ultraviolet rays is irradiated, a part of the energy of the radiation is accumulated in the phosphor, and when the phosphor is irradiated with excitation light such as visible light. ,
It is known that a phosphor emits stimulated emission according to the stored energy.

[0004] Phosphors exhibiting such properties are called storage phosphors (stimulable phosphors). For example, as shown in JP-A-55-12429 and JP-A-56-11395, the use of this stimulable phosphor allows radiation image information of a subject such as a human body to be stored on the stimulable phosphor sheet. Once recorded, the stimulable phosphor sheet is scanned with excitation light such as laser light to generate stimulated emission light, and an image signal is obtained by photoelectrically reading the obtained stimulated emission light. A radiation image information recording / reproducing system that outputs a radiation image of a subject as a visible image to a recording material such as a photographic photosensitive material or a display device such as a CRT based on the image signal has been proposed.

[0005] In recent years, as a third imaging method, an imaging system for similarly capturing an X-ray image using a semiconductor sensor has been developed. Compared to a radiographic system using conventional silver halide photography, this imaging system has a practical advantage that an image in an extremely wide radiation exposure area can be recorded. That is, after the X-rays having a very wide dynamic range are read by the photoelectric conversion means and converted into electric signals, the electric signals are used to visualize the radiation image on a recording material such as a photographic photosensitive material or a display device such as a CRT. By outputting the image as an image, it is possible to obtain a radiation image that is hardly affected by fluctuations in the exposure amount of radiation.

FIG. 16 is a schematic diagram of a radiographic image capturing system using the above-described semiconductor sensor. The X-ray image capturing apparatus 1 has a built-in X-ray detection sensor 2 and emits light by an X-ray generator 3. The irradiated X-ray is irradiated on the subject S,
X-rays transmitted through the subject S are detected by an X-ray detection sensor 2 having a detection surface on which a plurality of photoelectric conversion elements are arranged two-dimensionally. The image signal output from the X-ray detection sensor 2 is subjected to digital image processing by the image processing means 4, and an X-ray image of the subject is displayed on the monitor 5.

FIG. 17 is a cross-sectional view of the X-ray imaging apparatus 1, which comprises a lower housing 11 and an upper housing 12, and is light-tightly coupled to the outside. A support member 13 for supporting the X-ray detection sensor 2 described above is provided on the lower housing 11, and the X-ray detection sensor 2 is coupled to the support member 13. Further, on the upper surface of the upper housing 12 located immediately before the X-ray detection sensor 2 such as an X-ray tube and a film, scattering X generated inside the subject S by X-ray irradiation is provided.
A grid 14 for removing scattered X-rays is provided to remove the rays and improve the contrast of the X-ray image.

Since the X-ray detection sensor 2 is vulnerable to impact, the surface of the X-ray detection sensor 2 is not brought into close contact with the upper housing 12, and a space 15 having a certain size is provided. The provision of the space 15 prevents the X-ray detection sensor 2 from being deformed even when the upper housing 12 is bent by an impact from above. In addition, even in a film / screen method and a computed radiography method other than the radiographic image capturing system using the semiconductor sensor, the image may be captured using the grid 14.

FIG. 18 is a cross-sectional view of the grid 14, in which a lead foil 22 made of lead having a high X-ray absorptivity and a lead foil 22 and Between the lead foils 22, an intermediate substance 23 made of aluminum, paper, wood, synthetic resin, carbon fiber reinforced resin or the like having a low X-ray absorption is provided.

The lead foil 22a located at the center of the grid 14 immediately below the X-ray source is perpendicular to the cover member 21.
In many cases, the convergence grid is inclined toward the X-ray source, such as the lead foils 22b and 22c, as it goes to the periphery. This convergence grid needs to be photographed with the distance between the grid and the light source and the center aligned. On the other hand, there is also a grid in which the lead foil 22 is not tilted, and this is called a parallel grid.

The amount of scattered radiation depends on the structure of the subject S. For example, a human body has a large amount of scattered radiation in the chest and abdomen, and has relatively few limbs. On the other hand, since the grid attenuates the transmitted X-rays, it is possible to perform imaging with a smaller radiation dose when imaging without using the grid as compared with imaging with using the grid. Therefore, a grid is used with priority on image quality in a part with a large amount of scattered radiation, and when a part with a relatively small amount of scattered radiation is photographed, photographing is often performed without using a grid in order to reduce the radiation dose. . Therefore, X
It is necessary for the line imaging apparatus that the grid can be easily attached and detached depending on the region to be imaged.

[0012]

However, in the above-mentioned conventional example, since the housing and the space exist between the X-ray detection sensor and the scattered X-ray removal grid, the X-ray detection sensor and the grid are in close contact with each other. As compared with the case where the image is displayed, the image is blurred and the image quality is apt to be deteriorated.

In general, in an upright imaging apparatus or an X-ray imaging apparatus mounted on a lying table, an excessive load is hardly applied directly to the upper housing 12, that is, an X-ray detection sensor is used in the upright imaging. 2 is arranged perpendicular to the floor,
The X-ray detection sensor 2 does not receive an excessive load in a direction perpendicular to the X-ray detection sensor 2 because the X-ray detection sensor 2 is in contact with the subject. In addition, when the X-ray imaging apparatus is mounted on the lying table, the subject rides on the top of the lying table and there is a space between the top plate and the X-ray apparatus. An excessive load is not applied in a direction perpendicular to the detection surface of the X-ray detection sensor 2 of the device.

However, for example, in the case of an X-ray imaging apparatus of a type in which a subject lies down on a table and is inserted between the subject and the table, such as a film cassette, X-ray detection is performed. An excessive load in the vertical direction is applied to the sensor housing.

FIG. 19 shows a state in which a load is directly applied to the X-ray imaging apparatus 1 shown in FIG. 17 from above, and shows a state in which the upper housing 12 is bent by receiving the load F. When the X-ray detection sensor 2 includes a member having a low strength with respect to a static load in a direction perpendicular to the detection surface, the X-ray detection sensor 2 and the upper housing 12 are arranged as shown in FIG. In the meantime,
It is necessary to prevent the load from being applied to the X-ray detection sensor 2 by providing a space larger than the deflection caused by the load.

For this reason, when the grid 14 is used outside the upper housing 12, it is necessary to provide a wider space between the grid 14 and the X-ray detection sensor 2, and there is a disadvantage that the image quality is deteriorated. Further, the grid 14 is also deformed by bending, and the focal length between the grid 14 and the X-ray detection sensor 2 changes, so that there is a disadvantage that an expected effect cannot be obtained.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide an X-ray image photographing apparatus capable of obtaining a good image irrespective of whether or not a grid is used.

[0018]

An X-ray imaging apparatus according to the present invention for achieving the above object irradiates an object with X-rays emitted from X-ray generating means, and obtains an X-ray distribution transmitted through the object. In an X-ray image photographing apparatus for detecting an X-ray detected by an X-ray detection unit incorporating X-ray detection means, the X-ray detection unit has a plurality of two-dimensionally arranged photoelectric conversion elements for detecting the X-ray transmitted through a subject. Said X-ray detection means having a detection surface;
A housing enclosing the X-ray detecting means, which scatters the distance between the light-receiving surface of the X-ray detecting means and the inner surface of the housing immediately above the light-receiving surface of the X-ray detecting means. The thickness of the X-ray removing grid is made substantially equal to or less than the thickness of the X-ray removing grid, and the scattered X-ray removing grid can be mounted between the X-ray detecting means and the housing immediately above the X-ray detecting means.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a perspective view of an X-ray detection unit incorporating X-ray detection means in the first embodiment, and FIG. 2 is a cross-sectional view. This portable X-ray detector 31
Is for detecting the distribution of X-rays generated from the X-ray generation unit and passing through the subject, and its exterior is made up of an upper housing 32 and a lower housing 33. The upper housing 32 and the lower housing 33 are made of a lightweight and high-strength material such as a magnesium alloy, a carbon fiber reinforced resin, or the like.
3 and the upper housing 32 are made light-tight. In order to insert the grid 34 into the upper housing 32, a slit-shaped opening 32 a whose thickness and width are slightly larger than the grid 34 is provided on the side surface of the upper housing 32. In addition, a concave portion 32b which is depressed from the side surface of the upper housing 32 is formed around the opening 32a.

A support plate 35 is provided in the lower housing 33, and an X-ray detection sensor 36 having a detection surface on which a plurality of photoelectric conversion elements are two-dimensionally arranged is mounted on the support plate 35. . In particular, the upper housing 32 located above the X-ray detection sensor 36 is provided with an X-ray transmittance of, for example, carbon fiber reinforced resin in order to minimize attenuation of X-rays reaching the X-ray detection sensor 36. High material is used.

At the end of the grid 34, a handle portion 34a thicker than other portions is attached.
A concave portion 32b is formed at the center of. Handle part 34
A lock switch 34c for fixing the grid 34 after the grid 34 has been inserted into the upper housing 32 is provided at the end of “a”. The grid 34 can be completely pulled out of the upper housing 32, and when completely mounted, can cover the entire image area of the X-ray detection sensor 36. A space 37 is provided between the front surface 36a of the X-ray detection sensor 36 and the back surface 32a of the upper housing 32 opposed to the front surface 36a, with a space having substantially the same dimension as the thickness of the grid 34.

Therefore, when inserting and removing the grid 34, the front surface 34d of the grid 34 and the rear surface 32a of the upper housing 32
In addition, the back surface 34e of the grid 34 and the surface 36a of the X-ray detection sensor 36 come into contact with each other, but since these surfaces are subjected to a process that is smooth and excellent in friction resistance, no scratch is generated.

Further, when the grid 34 is completely pulled out from the upper housing 32, a shutter 38 is rotated inside the opening 32a with the rotation center 38a as a fulcrum in order to close the opening 32a in a light-tight manner. The shutter 38 is movably supported, and the shutter 38 is retracted downward with the rotation center 38a as a fulcrum when the grid 34 is inserted.

FIG. 3 is a cross-sectional view of the X-ray detection unit 31 in a state where the grid 34 is completely inserted into the upper housing 32. The handle 34a of the grid 34 is engaged with the recess 32b of the upper housing 32. Accordingly, even though the shutter 38 is retracted, light can be prevented from entering through the opening 32a, and the inside of the X-ray detection unit 31 can be kept light-tight. In this state, the grid 34 is fixed to the upper housing 32 by setting the lock switch 34c in the locked state, and the grid 34 does not fall out of the X-ray detection unit 31 unless the lock switch 34c is released. By arranging the grid 34 almost in close contact with the upper surface of the X-ray detection sensor 36, a good image with high contrast can be obtained.

When a load is applied to the upper surface of the upper housing 32 and the opening 32a is deformed so as to close it, the thickness of the grid 34 should be substantially the same as the opening width of the opening 32a. From the upper housing 3
2 can be prevented. Also, the handle part 34a
Also, since it is engaged with the concave portion 32b, it also receives a load similarly and functions to prevent deformation of the upper housing 32.

FIG. 4 is a cross-sectional view of the X-ray detector 31 in a state where the grid 34 is completely pulled out of the upper housing 32.
The shutter 38 is pivoted by the urging means (not shown).
The inside of the X-ray detection unit 31 is kept light-tight by being urged clockwise around the center a to close the opening 32a.

FIG. 5 is an explanatory view showing a state in which a load is applied to the X-ray detection unit 31 in this embodiment.
Reference numeral 6 denotes a member that is strong against a static load in a direction perpendicular to the detection surface.

Accordingly, the external load F can be supported by the support plate 35 and the lower housing 33 via the X-ray detection sensor 36. That is, the X-ray detection sensor 36 comes into contact with the deflection caused by the load of the upper housing 32 and receives the deflection. Although the X-ray detection sensor 36 has low strength against bending, the support plate 35 and the lower housing 33 have sufficient strength against expected bending, so that the X-ray detection sensor 36
The X-ray detection sensor 36 is not damaged even if a bending load is applied due to the bending of 2.

With such a configuration, the grid 34 and the X
There is no need to provide a space between the line detection sensors 36,
Good images can be obtained. Furthermore, the grid 34 is less deformed and the expected effect is obtained.

FIG. 6 is a cross-sectional view of the X-ray detector 31 in which a foam member 41 made of a synthetic resin having a shock absorbing ability is inserted in place of the grid 34.
A handle portion 41a having the same function as the grid 34 is provided at one end. However, the handle portion 41a is not a foamed member, but a member having a certain strength. With such a configuration, the X-ray detection sensor 36 can be protected by the foam member 41 even when an impact is applied to the upper housing 32.

FIG. 7 is a perspective view of an X-ray detection sensor 51 which is a modification of the X-ray detection sensor 36. The X-ray detection sensor 51 is similar to the X-ray detection sensor 36, and is similar to the support plate 35.
However, the X-ray detection sensor 51 is provided with ends 51b and 51c parallel to the insertion direction of the grid 34, and these ends 51b and 51c have a slightly raised shape than the central portion 51a. Has become.

By adopting such a shape, it is possible to reduce the resistance when the grid 34 or the foam member 41 is inserted and removed. The lower end of the grid 34 parallel to the grid insertion direction may be slightly raised in the same manner.

FIG. 8 is a cross-sectional view of the X-ray detector 61 in a state where the grid is not inserted in the second embodiment. In the present embodiment, the support 63 that supports the X-ray detection sensor 62 is urged by the compression spring 64 toward the upper housing 32. Further, an inclined portion 62a is provided at an end of the X-ray detection sensor 62 on the side of the opening 32a.

Accordingly, the upper surface 62b of the X-ray detection sensor 62
Can be brought into close contact with the back surface 32c of the upper housing 32 by the compression spring 64. Compared with the first embodiment shown in FIG. 4, in this embodiment, the distance between the X-ray detection sensor 62 and the upper housing 32 is increased. The space can be omitted, the subject S and the X-ray detection sensor 62 can be made closer to each other, and a good image with less blur can be obtained.

FIG. 9 is a cross-sectional view of the X-ray detector 61 in which the grid according to the second embodiment is inserted. The grid 65 is provided with a handle 65a similarly to the grid 34, and a tip portion is provided with an inclined portion 65b.

As a result, the grid 65 is moved to the opening 32a.
When the X-ray detection sensor 62 is inserted from above, after the inclined portion 65b of the grid 65 and the inclined portion 62a of the X-ray detection sensor 62 come into contact with each other, the X-ray detection sensor 62 is pushed down by using the insertion force, and The distance between 62 and upper housing 32 is substantially equal to the thickness of grid 65.

The X-ray detection unit 61 in this embodiment moves the X-ray detection sensor 62 close to the subject S in the case of photographing without using the grid 65, and the X-ray detection sensor in the case of photographing using the grid 65. It is only necessary to retract the 62 by a necessary minimum distance, and a good image with little blur can be obtained by any of the photographing methods.

FIG. 10 is a cross-sectional view of the X-ray detecting unit 71 according to the third embodiment with no grid inserted. In this embodiment, the side portion 72 of the lower housing 72 is provided.
a and 72b are shaped to penetrate inside the side portions 73a and 73b of the upper housing 73, and the lower housing 72 and the upper housing 73 are fitted to make the X-ray detector 71 light-tight. Be able to hold. The side surface portions 72a and 72b are slidable with the side surface portions 73a and 73b, respectively.
The outer thickness in the direction perpendicular to the detection surface of No. 4 can be changed.

Further, an X-ray detection sensor 74 is fixed to the lower housing 72 via a support plate 75. A tension spring 76 is fixed to both ends of the inner surface of the lower housing 72,
The other end of the tension spring 76 is fixed to the inner surface of the upper housing 73, and urges in a direction in which the distance between the two is reduced. Further, an inclined portion 72c is provided above the side surface portion 72a of the lower housing 72.

A chopper 77 is fixed to the inner surface of the upper housing 73, and a photo interrupter 78 having a U-shaped cross section is provided in the lower housing 72. When the chopper 77 is inserted into the photo interrupter 78, the light of the photo interrupter 78 is blocked.

FIG. 11 is a cross-sectional view of the X-ray detecting section 71 of the third embodiment with the grid 65 inserted, and when the grid 65 is inserted, the inclined portion 65b of the grid 65 and the X-ray detection sensor 74 are brought into contact with each other, and the tension spring 76
, The space between the lower housing 72 and the upper housing 73 is separated by an amount equal to the thickness of the grid 65. In this state, the chopper 77 is retracted to a position where the light beam of the photo interrupter 78 is not blocked, and the presence or absence of the grid 65 can be detected based on the presence or absence of the blocked light beam.

Therefore, in this embodiment, the grid 65
Is not inserted, the thickness of the X-ray detector 71 can be further reduced. In addition, the movable part by the shutter can be omitted, and the mechanism can be simplified. Further, the presence or absence of the grid 65 can be detected, information can be transmitted to the operator, and an erroneous operation can be prevented. Note that the detection mechanism in the present embodiment can be applied to the second embodiment.

FIG. 12 is a cross-sectional view of the X-ray detector 81 in the state where the grid is not inserted in the fourth embodiment, and is a modification of the second embodiment. In the present embodiment, a lower housing 82 and an openable and closable upper housing 83 are joined in a light-tight manner.
Can be opened and closed with the fulcrum as a fulcrum. X-ray detection sensor 3
6 is fixed on a support plate 63, and is urged by a compression spring 64 to the lower surface 82 b of the lower housing 82.

FIG. 13 is a sectional view showing a state in which the upper housing 83 is opened about the center of rotation 46a, and FIG.
Is shown in a sectional view in a state where the upper housing 83 is closed. A protrusion 84 a is provided at an end of the grid 84, and the grid 84 can be positioned by engaging with an end of the X-ray detection sensor 36.

In this embodiment, when the grid 84 is inserted, the X-ray detection sensor 36 and the grid 84 do not come into sliding contact with each other, so that it is not necessary to apply a friction resistance treatment to both.

FIG. 15 is a cross-sectional view of the X-ray detector 91 in the fifth embodiment, which is a modification of the first embodiment. A dust-proof film 92 is provided instead of the shutter 38 in the first embodiment.
Numeral 2 is made of a material having no translucency and good transmissivity to X-rays, and has a bag shape large enough to include a grid (not shown). The opening of this bag is lightly and confidentially coupled to the opening 93a of the upper housing 93.

The grid is to be mounted in the dustproof film 92 through the opening 93a, as in the first embodiment.
By providing the recess 93b in the upper housing 93, it is possible to prevent external dust from entering the inside of the X-ray detection unit 91 due to insertion and removal of the grid.

[0048]

As described above, in the X-ray imaging apparatus according to the present invention, the grid can be easily attached and detached, and the use of the grid can be selected depending on the imaging site. Further, since the interval between the grid and the X-ray detecting means can be minimized, a good image with little blur can be obtained regardless of whether or not the grid is used.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment.

FIG. 2 is a sectional view of the first embodiment.

FIG. 3 is a sectional view of the first embodiment.

FIG. 4 is a sectional view of the first embodiment.

FIG. 5 is a sectional view of the first embodiment.

FIG. 6 is a perspective view of an X-ray detection sensor.

FIG. 7 is a sectional view of the second embodiment.

FIG. 8 is a sectional view of the second embodiment.

FIG. 9 is a sectional view of the third embodiment.

FIG. 10 is a sectional view of a third embodiment.

FIG. 11 is a sectional view of the fourth embodiment.

FIG. 12 is a sectional view of a fourth embodiment.

FIG. 13 is a sectional view of a fourth embodiment.

FIG. 14 is a sectional view of the fourth embodiment.

FIG. 15 is a sectional view of the fifth embodiment.

FIG. 16 is a schematic diagram of a radiation image capturing system.

FIG. 17 is a cross-sectional view of the X-ray imaging apparatus.

FIG. 18 is a sectional view of a grid.

FIG. 19 is a cross-sectional view of the X-ray imaging apparatus.

[Explanation of symbols]

 31, 61, 71, 81, 91 X-ray detectors 32, 73, 83 Upper case 33, 72, 82 Lower case 34, 65, 84 Grid 35, 63, 75 Support plate 36, 51, 62, 74 X Line detection sensor 38 Shutter 64, 76 Spring

Claims (7)

[Claims] 1. An X-ray imaging apparatus, comprising: irradiating an object with X-rays emitted from an X-ray generation unit, and detecting an X-ray distribution transmitted through the object by an X-ray detection unit having a built-in X-ray detection unit. An X-ray detection unit, the X-ray detection unit having a detection surface on which a plurality of photoelectric conversion elements are two-dimensionally arranged to detect the X-ray transmitted through a subject, and a housing including the X-ray detection unit. The distance between the light receiving side surface of the X-ray detecting means and the inner surface of the housing directly above the light receiving side surface of the X-ray detecting means is substantially equal to the thickness of the scattered X-ray removing grid or An X-ray image photographing apparatus characterized in that the X-ray grid is made to be substantially equal or less, and the scattered X-ray removing grid can be mounted between the X-ray detecting means and the housing directly above the X-ray detecting means. 2. Instead of the scattered X-ray removal grid,
2. The X-ray image photographing apparatus according to claim 1, wherein a buffer member for reducing an external impact applied to the housing portion immediately above a surface on a light receiving side of the X-ray detecting means can be attached. 3. The scattered X-ray removal grid has an opening for mounting the scattered X-ray removal grid, and a part of the scattered X-ray removal grid closes the opening in a light-tight manner. Item 7. An X-ray image photographing apparatus according to Item 1. 4. The housing has an opening for mounting the scattered X-ray removal grid, and a part of the scattered X-ray removal grid is engaged with the opening and the opening is provided. The X-ray imaging apparatus according to claim 1, comprising a strength member that resists deformation of the X-ray image. 5. The space between the light receiving side surface of the X-ray detecting means and the inner surface of the housing immediately above the light receiving side surface of the X-ray detecting means can be changed. 2. The device according to claim 1, wherein when not mounted, the surface on the light receiving side of the X-ray detecting unit and the inner surface of the housing immediately above the surface on the light receiving side of the X-ray detecting unit are substantially in close contact with each other. X-ray imaging device. 6. The apparatus according to claim 1, further comprising means for detecting a relative change in the distance between the surface on the light receiving side of the X-ray detecting means and the inner surface of the housing immediately above the surface on the light receiving side of the X-ray detecting means. The X-ray image capturing apparatus according to the above. 7. The X-ray imaging apparatus according to claim 1, wherein the opening and closing of the opening is performed by a part of the housing by a relative movement operation of the X-ray detection unit and the housing. .