Information
-
Patent Grant
-
6671348
-
Patent Number
6,671,348
-
Date Filed
Friday, July 6, 200123 years ago
-
Date Issued
Tuesday, December 30, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Fitzpatrick, Cella, Harper & Scinto
-
CPC
-
US Classifications
Field of Search
US
- 378 70
- 378 86
- 378 87
- 378 88
- 378 89
- 378 140
- 378 145
- 378 149
- 378 154
-
International Classifications
-
Abstract
In an X-ray image detector including an X-ray grid unit for transmitting primary X-rays and removing scattered X-rays, a fluorescent substance for emitting fluorescence through excitation by X-rays, and photoelectric conversion elements for photoelectrically converting the fluorescence, these X-ray grid unit, fluorescent substance and photoelectric conversion elements are constituted together as a single unit. The plurality of photoelectric conversion elements are arranged two-dimensionally between each adjacent two of which there is a predetermined insensitive region. The X-ray grid is composed of a plurality of X-ray absorption members for removing the scattered X-rays, and the X-ray absorption members are disposed substantially only on the predetermined insensitive regions when viewed from a direction from which X-rays are incident. Further, the fluorescent substance is disposed substantially only in the regions between the X-ray absorption members that are adjacent to each other when viewed from a direction from which X-rays are incident.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an X-ray image detecting apparatus for detecting an X-ray image of a subject, such as a person to be examined for diagnosis or the like.
2. Description of the Related Art
Recently, X-ray image acquisition systems for taking X-ray images of subjects being examined for diagnosis using semiconductor sensors have been developed.
When compared with conventional X-ray radiographic systems employing ordinary silver halide photography, these X-ray image acquisition systems have such advantages in practical use that images can be recorded which have a very wide dynamic range corresponding to a very wide range in the amount of radiation, to which the sensor is exposed. That is, X-ray images can be obtained which are unlikely to be affected by variations in the amount of exposure of radiation; after X-rays with a very wide dynamic range are read with a detector including a photoelectric transducer and converted into an electric signal, the electric signal is processed so as to output X-ray images on recording materials such as a photosensitive material, and the like and on display units such as a CRT, and the like, as visible images. In this radiography, an X-ray grid, which removes scattered X-rays generated in subjects, are used in many cases in order to improve contrast in a radiographic image.
FIG. 1
is a sectional view of an X-ray grid and a detector used in a conventional radiographic apparatus. An X-ray image detector
1
is arranged such that a plurality of photoelectric conversion elements
3
are two-dimensionally disposed on an insulation substrate
2
, and further, fluorescent substance
4
is laminated on the photoelectric conversion elements
3
. In addition, a grid
5
is disposed above the X-ray image detector
1
with a predetermined space therebetween. The grid
5
is arranged such that foils
7
, which are composed of lead or the like, having a high X-ray absorption ratio, and intermediate materials
8
, which are composed of aluminum or the like, having a low X-ray absorption ratio, are held by a cover member
6
. Using the grid
5
arranged as described above permits primary X-rays L
1
, which have passed through a subject without being scattered thereby, to pass through the grid
5
and to reach the fluorescent substance
4
of the X-ray image detector
1
. When X-rays L
1
are irradiated onto the fluorescent substance
4
, the optical materials (light emitting materials) in the fluorescent substance
4
are excited and emit fluorescence L
2
having a wavelength within the spectral sensitivity wavelength range of the photoelectric conversion elements
3
. Further, X-rays which are incident on the grid
5
with a large angle with respect to the primary X-rays L
1
, such as a scattered X-ray component L
3
generated by the subject, are absorbed by the foils
7
.
During exposure of radiation, the grid
5
is moved in a direction B or C by a drive unit (not shown). With this operation, an excellent image can be obtained by the X-ray image detector
1
which has no image component of stripes of the grid
5
as well as no moires or aliasing caused by a difference between the pitch of the foils
7
and the pitch of the pixels of the X-ray image detector
1
.
Radiography is required to satisfy contradictory conditions (1) that an excellent image with a high contrast is to be obtained while (2) reducing the dosage of the subjects as much as possible by reducing the amount of X-rays with which they are irradiated. However, the grid
5
shown in
FIG. 1
may act as a factor for deteriorating an image by reducing the intensity of X-rays on the X-ray image detector
1
.
One reason for this reducing of the intensity of X-rays is that the X-rays L
1
, which reach the X-ray image detector
1
, must pass through the intermediate materials
8
. While the intermediate materials
8
are composed of aluminum or the like having a high X-ray transmission ratio as described above, that transmittance is not 100% as a matter of fact. When, for example, the thickness Δ1 of the foils
7
is set to 43 μm at a time a grid density is 40 lines/cm and a grid ratio is 10:1, the intermediate materials
8
have a thickness Δ2 of 207 μm (=1 cm/40−Δ1) and a height Δ3 of 2070 μm (=Δ2×10).
When the intermediate materials
8
are composed of aluminum, the aluminum in the above case has a thickness of about 2 mm, and the primary X-rays L
1
have a transmittance of about 70%. Accordingly, about 30% of the intensity of the X-rays will be lost. Further, when viewed from the direction from which the X-rays are incident, 17% (=Δ1/(Δ2+Δ1)) of the grid
5
is composed of lead through which X-rays do not pass. Accordingly, the total X-ray transmittance of the grid
5
is about 60% (0.7×(1−0.17)) when the loss of the intermediate materials
8
is also taken into consideration, which means that the reduction of the intensity of X-rays caused by the grid
5
is large and cannot be ignored.
Further, the fluorescence L
2
generated in the fluorescent substance
4
by the primary X-rays which have passed through the grid
5
, radiates in various directions because the fluorescent substance
4
is formed in a continuous flat shape so as to entirely cover the photoelectric conversion elements
3
. Accordingly, this fluorescence L
2
reaches not only a photoelectric conversion element
3
a
located just below a position where it emits but also other photoelectric conversion elements, for example,
3
b
, and the like adjacent to the photoelectric conversion element
3
a.
Therefore, as described below, the grid
5
reduces the intensity of X-rays, while it does remove the incident scattered X-ray component L
3
. Further, the continuous flat-shaped fluorescent substance
4
may deteriorate the MTF (modulation transfer function) of the X-ray image detector because the fluorescence L
2
generated in the fluorescent substance
4
reaches a plurality of adjacent photoelectric conversion elements. Furthermore, when the intensity of the emitting fluorescence L
2
is increased by increasing the thickness of the fluorescent substance
4
to improve the intensity of signals outputted from the photoelectric conversion elements
3
, the above tendency becomes stronger, and improvement of the sensitivity of X-ray image detectors may be impeded.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention, which was made based on the above recognition of the problem, to provide an excellent X-ray image detecting apparatus capable of obtaining a good image having a high contrast while reducing the dosage received by a subject.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a sectional view of an X-ray grid and a detector of a conventional X-ray image detecting apparatus;
FIG. 2
is a schematic view of a radiographic system;
FIG. 3
is a sectional view of a first embodiment of an X-ray image detecting apparatus of the present invention;
FIG. 4
is a plan view of the first embodiment the X-ray image detecting apparatus of the present invention;
FIG. 5
is a sectional view of a second embodiment of the X-ray image detecting apparatus of the present invention;
FIG. 6
is a sectional view of a third embodiment of the X-ray image detecting apparatus of the present invention; and
FIG. 7
is a sectional view of a fourth embodiment of the X-ray image detecting apparatus of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described below in detail with reference to the embodiments shown in to
FIGS. 2
to
7
.
FIG. 2
shows an overall schematic view of a radiographic system.
A radiographic apparatus
11
includes an X-ray image detecting apparatus
12
having a detecting surface on which a plurality of photoelectric conversion elements are disposed two-dimensionally. As will be described below, the X-ray image detecting apparatus
12
includes an X-ray image detector in which X-ray grids, fluorescent substances (which serve, as is well known, to convert incident X-rays to light of a predetermined wave-length; such substances, and any and all arrangements that can transform X-rays to light, are herein referred to sometimes as an X-ray converter or conversion member) and the photoelectric conversion elements are constituted together as a unit, i.e., integrated in one united body. X-rays irradiated from an X-ray generator
13
having an X-ray tube are applied to a person S as a subject being examined for diagnosis, and X-rays that have passed through the person S are detected by the X-ray image detecting apparatus
12
. Thus-obtained image data is digitally processed by an image processing apparatus
14
including a computer, and the image data that has been processed is stored in the computer as well as displayed on a display unit
15
as an X-ray image of the person being examined.
FIG. 3
is shows a sectional view of an X-ray image detector
21
built in the X-ray image detecting apparatus
12
. The X-ray image detector
21
is arranged such that a plurality of photoelectric conversion elements
23
are disposed two-dimensionally on the plane of an insulation substrate
22
, the plane extending in the direction perpendicular to the sheet surface of
FIG. 3
, and further, a grid unit
24
is disposed on the photoelectric conversion elements
23
, that is, at a side toward incident X-rays. In addition, the spaces between the photoelectric conversion elements
23
are arranged as insensitive regions
25
, which have no sensitivity to fluorescence.
A glass sheet is used as the insulation substrate
22
because it does not chemically act on semiconductor devices that form the photoelectric conversion elements
23
and the like, endures the high temperatures involved in semiconductor manufacturing processes, is stable dimensionally, and is able to have a high degree of flatness.
The grid unit
24
has grids which are formed of foils
26
composed of lead having a large x-ray absorption ratio, and the spaces between the respective grids are filled with fluorescent substances
27
and intermediate substances
28
, sequentially in this order, in a direction opposite to the direction from which X-rays are incident. A photoelectric conversion element
23
is disposed just under a corresponding fluorescent substance
27
, which is located between each pair of grids, and as well, each photoelectric conversion elements
23
is disposed so as to avoid a portion shaded by a foil
26
, and the shaded portion is arranged as an insensitive region
25
. The thickness of each foil
26
is in approximate agreement with the width of the insensitive region
25
.
The fluorescent substances
27
located between the respective grids are spatially separated from each other by the foils
26
in order to prevent crosstalk in which fluorescence L
2
generated by the fluorescent substances
27
on the respective photoelectric conversion elements
23
is incident on adjacent photoelectric conversion elements
23
. The intermediate substances
28
are disposed to reinforce the foils
26
having low rigidity and composed of aluminum, paper, wood, synthetic resin or carbon-fiber-reinforced resin, or the like, having a small X-ray absorption ratio. The fluorescent substances
27
are partitioned by the foils
26
, and the intermediate substances
28
are laminated or layered on the fluorescent substances
27
. While the foils
26
are mainly composed of lead, when the surfaces thereof are arranged as reflecting surfaces for reflecting fluorescence, fluorescence generated by the fluorescent substances
27
is reflected on the foils
26
, which increases the amount of fluorescence incident on corresponding photoelectric conversion elements
23
, thereby improving the S/N of a detection signal.
FIG. 4
is a sectional view of the X-ray image detector
21
shown in
FIG. 3
when it is viewed from a direction D (an x-ray incident direction). Each photoelectric conversion element
23
is formed in an approximate square shape, and each grid formed by the foils
26
have a slit or strip shape. The grids are filled with intermediate substances
28
having a slit shape formed in accordance with the shape of the grids. The photoelectric conversion elements
23
formed just under the intermediate substances
28
, each having the approximately square shape, are distributed two-dimensionally. Insensitive regions
29
are formed between the respective photoelectric conversion elements
23
. Note that it is not always necessary that the girds formed by an X-ray grid be formed in a shape of stripes, and they may instead be formed in a matrix shape. In this case, the respective grids may be formed in a quadrangular shape (a square shape or a rectangular shape) or may be formed in a polygonal shape other than a quadrangular shape, for example, in a hexagonal honeycomb shape.
Since primary X-rays L
1
are incident on the grid unit
24
in approximately parallel to the foils
26
, they pass through the intermediate substances
28
and reach the fluorescent substances
27
and make it emit the fluorescence L
2
, to which the photoelectric conversion elements
23
have sensitivity, in the fluorescent substances
27
. While the fluorescence L
2
is emitted at various angles, it does not reach other adjacent photoelectric conversion elements
23
because it does not pass through the foils
26
. In contrast, since scattered X-rays L
3
are incident on the grid unit
24
obliquely to (i.e., not parallel to) the foils
26
but at a certain angle with respect to it, most of the scattered X-rays L
3
are absorbed by the foils
26
, and the ratio of them that reach the fluorescent substances
27
or the photoelectric conversion elements
23
is small.
Since the foils
26
exist only on the insensitive regions
25
between the photoelectric conversion elements
23
, they do not block the X-rays to be intrinsically detected that are not scattered by the subject and incident toward the fluorescent substances
27
on the photoelectric conversion elements
23
. Therefore, the reduction of the transmittance of X-rays, which is determined by the ratio of the thicknesses of the intermediate substances
28
and the foils
26
(opening ratio), does not occur in this arrangement, while this reduction is a problem in the conventional art employing the moving grid.
When, for example, it is assumed in the conventional example shown in
FIG. 1
that the foils
7
have a thickness of 43 μm and the intermediate substances
8
have a thickness of 207 μm, about 17% of the arrangement (43/(43+207)) blocks the transmission of X-rays, and thus their opening ratio is 83%. In contrast, in this embodiment, an opening ratio of 100% can be secured while having the grid unit
24
. This means that sensitivity can be improved about 20% while using the same photoelectric conversion elements
23
, which permits a reduction in dosage received by persons being examined.
Further, in the X-ray image detector of this embodiment, the foils
26
exhibit multiplied actions not only removing the scattered X-rays L
3
incident on the foils
26
but also solving the problem which is caused by the diverged component or the scattered component of the fluorescence L
2
by spatially separating the fluorescent substances
27
. That is, the foils
26
reduce the above-mentioned crosstalk between adjacent photoelectric conversion elements. By this arrangement, the MTF can be improved, and an excellent X-ray image can be taken.
Further, while the fluorescent substances
27
are formed continuously in the direction perpendicular to the sheet surface (the depth direction) of
FIG. 3
in the above embodiment, the fluorescent substances
27
located on the insensitive regions
29
may be removed in correspondence to the approximately square shape of the photoelectric conversion elements
23
. In this case, the MTF also will be improved in this direction (the depth direction). The grid unit
24
arranged as described above, of which a grid ratio (i.e., height of the foil of the grid as shown in the Figures divided by spacing between adjacent vertical foils of the grid) is preferably set to at least 3:1, can achieve a large effect for removing the scattered X-rays L
3
.
FIG. 5
shows a sectional view of a second embodiment of the X-ray image detecting apparatus of the present invention, wherein the same components as used in the first embodiment are denoted by the same reference numerals. The second embodiment is different from the first embodiment as described below. That is, in the first embodiment, the grid unit
24
is arranged as a parallel grid all foils of which are disposed parallel to each other, whereas in the second embodiment, a grid unit
32
of an X-ray image detector
31
is arranged as a converging grid foils of which are tilted symmetrically with respect to a center line Z acting as a symmetrical axis.
Specifically, foils
33
a
in the vicinity of the center line Z are disposed perpendicular to the detecting surfaces of photoelectric conversion elements
23
, and foils
33
b
in the periphery of the grid unit
32
are tilted with respect to the direction of the center line Z. The angle θ of foils
33
with respect to the normal Y of the detecting surfaces of the photoelectric conversion elements
23
is 0 in the vicinity of the center line Z, and increases with distance of the foil
33
from the center line Z. Note that the extending lines of all the foils
33
(i.e., the planes of all the foils) intersect with each other at one point (focal point) on the center line Z. Ordinarily, a radiographic system is arranged such that this focal point is in approximate agreement with the emitting point of an X-ray source from which X-rays emit.
When an X-ray image is taken using the converging grid together with an X-ray tube having an emitting point located at the focal point of the converging grid, a still more excellent image can be obtained which does not have any vignetting caused by the foils
33
even in the periphery of the grid unit
32
, that is, in which the intensity of X-rays is not reduced even in the periphery thereof.
FIG. 6
is a sectional view of a third embodiment of the X-ray image detecting apparatus
41
of the present invention. In the previous embodiments, the flourescent substances in the grid unit of the X-ray image detector are partitioned by the grid foils. In the third embodiment, however, partitions
43
, which are different from grid foils
26
, are disposed only in the portions where flourescent substances
27
are partitioned so that adjacent flourescent substances can be spatially separated from each other by the partitions
43
. The partitions
43
have a property that they do not transmit the fluorescence L
2
, since they block it by reflecting or absorbing it, while they may absorb the X-rays in a small amount.
In a grid unit
42
arranged as described above, the foils
26
can remove scattered X-rays incident downward, and as well, the partitions
43
can prevent the diverged or scattered component of the fluorescence L
2
generated in the fluorescent substances from invading into adjacent regions, whereby occurrence of crosstalk can be prevented. Further, the portion of the grid unit
42
excluding the fluorescent substances
27
and the partitions
43
has a structure in which only the foils
26
and intermediate substances
28
are alternately disposed, and thus the portion of the grid unit
42
can be simply made by a conventional manufacturing method.
Note that, as a modification, a similar function also can be obtained in an arrangement in which the portions of the partitions
43
are composed of simple cavities, the fluorescent substances
27
are spatially separated for each grid, and a reflecting layer or a shading layer is formed on a side of each fluorescent substance
27
.
FIG. 7
shows a sectional view of a fourth embodiment of the X-ray image detecting apparatus of the present invention. Each of the foils
26
of a grid unit
52
of an X-ray image detector
51
is supported with its lower end inserted into one of a plurality of grooves
53
a
formed on the upper surface of a resin plate
53
. Further, a plurality of recesses
53
b
are formed on the lower surface of the resin plate
53
at the same pitch as the foils
26
and are filled with fluorescent substances
27
. That is, the fourth embodiment has a structure in which the fluorescent substances
27
are spatially separated in correspondence to the spaces between the respective foils. Note that the resin plate
53
has a property that it blocks fluorescence emitted from the fluorescent substances
27
by reflection, absorption or the like. Otherwise, the resin plate
53
b
is provided with this property. In contrast, the upper ends of the foils
26
are held by a resin plate
54
having grooves
54
a
formed thereon at the same pitch as the grooves
53
a
. The grid unit
52
has sufficient rigidity because the foils
26
are held by the grooves
53
a
and
54
a
, which permits the spaces between the foils
26
to be arranged as cavities
55
without being filled with intermediate substances.
This arrangement can avoid a loss caused when X-rays pass through the intermediate substances, in addition to being able to remove any scattered X-rays and crosstalk that is caused by fluorescence. For example, when the intermediate substances
28
in the first embodiment are composed of aluminum having a thickness of 2 mm, they have a transmittance for the X-rays L
1
of about 70%. That is, sensitivity can be improved about 40% (≈1/0.7−1) by the removal of the intermediate substances. As a result, compatibility can be established between a further reduction in the dosage received by the subject and improvement of image quality.
Note that rigidity may be further improved by providing cover portions or bonded layers on the surfaces of the grid foils, in the spaces between the grid foils and the fluorescent substances, or in the spaces between the fluorescent substances and the photoelectric conversion elements.
The employment of the grid unit
52
arranged as described above can remove a large amount of a scattered X-ray component, and can reduce crosstalk between the respective photoelectric conversion elements due to converged fluorescence, whereby image contrast can be improved, and as well, a decrease in the intensity of X-rays can be reduced when they transit the grid unit. That is, the reduction of the dosage received by subjects and the improvement of image quality, which are ordinarily inconsistent with each other, can be satisfied at the same time.
The X-ray image detecting apparatus using the X-ray image detectors of all of the embodiments described above has such advantages as high reliability, less expensive cost and easy maintenance because it can obtain an excellent image without the need for a mechanism for moving an X-ray grid.
Further, it is needless to say that the above-mentioned third and fourth embodiments may employ a converging grid, as in the second embodiment.
As described above, according to the X-ray image detecting apparatus of the present invention, an excellent image having high contrast can be obtained while reducing the dosage received by the subject.
While the present invention has been described with reference to what are presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
Claims
- 1. An X-ray image detecting apparatus comprising:an X-ray grid arranged to remove X-rays scattered by a subject; a conversion member for converting X-rays passed by said X-ray grid into light having a predetermined wavelength; and a plurality of photoelectric conversion elements arranged to receive light from said conversion member, wherein said plurality of photoelectric conversion elements are arranged two-dimensionally spaced apart from each other and have predetermined insensitive regions disposed between said photoelectric conversion elements, said X-ray grid comprises a plurality of X-ray absorption members for removing scattered X-rays, each of said X-ray absorption members being arranged substantially only on said insensitive regions when viewed from a direction from which x-rays are incident, and said conversion member is arranged only in regions between said X-ray absorption members that are substantially adjacent to each other when viewed from the direction from which X-rays are incident.
- 2. The apparatus according to claim 1, wherein said conversion member is partitioned by said X-ray absorption members.
- 3. The apparatus according to claim 1, wherein said conversion member is partitioned by predetermined members which are different from said X-ray absorption members and located adjacent to each other.
- 4. The apparatus according to claim 3, wherein said predetermined members have a property of substantially not transmitting the light from said conversion member.
- 5. The apparatus according to claim 1, wherein said conversion member is partitioned by cavities, and wherein the surface of said conversion member facing said cavities has a property of substantially not transmitting the light from said X-ray conversion member.
- 6. The apparatus according to any one of claims 1 or 2 to 5, wherein when viewed from a direction from which X-rays are incident, said X-ray absorption members are arranged in a stripe pattern and said conversion member is divided into parts, in a direction along said X-ray absorption members, in correspondence to respective ones of said photoelectric conversion elements.
- 7. The apparatus according to any one of claims 1 or 2 to 5, wherein said X-ray grid is a converging grid having a predetermined focal point.
- 8. The apparatus according to any one of claims 1 or 2 to 5, wherein said X-ray grid comprises intermediate substances disposed between said X-ray absorption members.
- 9. The apparatus according to claim 1, further comprising:a first member, for supporting one end of each of said X-ray absorption members on one surface of said first member as well as holding said conversion member on another surface of said first member; and a second member, for holding another end of each of said X-ray absorption members.
- 10. The apparatus according to claim 9, wherein said first member separates and holds said conversion member so that said conversion member is disposed substantially only in regions between said X-ray absorption members that are adjacent to each other when viewed from a direction from which X-rays are incident.
- 11. The apparatus according to claim 10, wherein said first member has a property of substantially not transmitting the light from said conversion member.
- 12. The apparatus according to claim 1, wherein said photoelectric conversion elements are arranged on an insulation substrate.
- 13. The apparatus according to claim 1, wherein said X-ray absorption members are arranged in a matrix or in a stripe pattern when viewed from a direction from which X-rays are incident.
- 14. The apparatus according to claim 1, wherein said X-ray absorption members have a property of reflecting the light from said conversion member.
- 15. The apparatus according to claim 1, wherein said X-ray grid has a grid ratio of at least 3:1.
- 16. An X-ray image acquisition apparatus comprising:an X-ray generator; and an X-ray image detector, wherein said X-ray image detector comprises: an X-ray grid arranged to remove X-rays scattered by a subject; a conversion member for converting X-rays passed by said X-ray grid into light having a predetermined wavelength; and a plurality of photoelectric conversion elements arranged to receive light produced by said conversion member, wherein said plurality of photoelectric conversion elements are arranged two-dimensionally with a predetermined insensitive region between each adjacent two of said photoelectric conversion elements, said X-ray grid comprising a plurality of X-ray absorption members for removing scattered X-rays, said X-ray absorption members are disposed substantially only on said insensitive regions when viewed from a direction from which X-rays are incident, and said conversion member is arranged only in regions between said X-ray absorption members that are substantially adjacent to each other when viewed from a direction from which X-rays are incident.
- 17. An X-ray image acquisition apparatus comprising:an X-ray image detector; and an image processor that receives and processes image data obtained using said X-ray image detector, wherein said X-ray image detector comprises: an X-ray grid; a conversion member for converting X-rays passed by said X-ray grid into light having a predetermined wavelength; and a plurality of photoelectric conversion elements arranged to receive light produced by said conversion member, wherein said plurality of photoelectric conversion elements are arranged two-dimensionally with a predetermined insensitive region between each adjacent two of said photoelectric conversion elements, said X-ray grid comprises a plurality of X-ray absorption members for removing scattered X-rays, said X-ray absorption members are disposed substantially only on said insensitive regions when viewed from a direction from which X-rays are incident, and said X-ray conversion member is arranged only in regions between said X-ray absorption members that are substantially adjacent to each other when viewed from a direction from which X-rays are incident.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-206418 |
Jul 2000 |
JP |
|
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