U.S. patent application number 11/812234 was filed with the patent office on 2008-12-18 for radiation image conversion panel, scintillator panel, and radiation image sensor.
This patent application is currently assigned to HAMAMATSU PHOTONICS K.K.. Invention is credited to Yutaka Kusuyama, Kazuhiro Shirakawa, Takaharu Suzuki, Toshio Takabayashi, Masanori Yamashita.
Application Number | 20080308734 11/812234 |
Document ID | / |
Family ID | 39930660 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080308734 |
Kind Code |
A1 |
Suzuki; Takaharu ; et
al. |
December 18, 2008 |
RADIATION IMAGE CONVERSION PANEL, SCINTILLATOR PANEL, AND RADIATION
IMAGE SENSOR
Abstract
The radiation image conversion panel in accordance with the
present invention has an aluminum substrate; an alumite layer
formed on a surface of the aluminum substrate; a chromium layer
covering the alumite layer; a metal film, provided on the chromium
layer, having a radiation transparency and a light reflectivity; an
oxide layer covering the metal film and having a radiation
transparency and a light transparency; a protective film covering
the oxide layer and having a radiation transparency and a light
transparency; and a converting part provided on the protective film
and adapted to convert a radiation image.
Inventors: |
Suzuki; Takaharu;
(Hamamatsu-shi, JP) ; Kusuyama; Yutaka;
(Hamamatsu-shi, JP) ; Yamashita; Masanori;
(Hamamatsu-shi, JP) ; Shirakawa; Kazuhiro;
(Hamamatsu-shi, JP) ; Takabayashi; Toshio;
(Hamamatsu-shi, JP) |
Correspondence
Address: |
DRINKER BIDDLE & REATH (DC)
1500 K STREET, N.W., SUITE 1100
WASHINGTON
DC
20005-1209
US
|
Assignee: |
HAMAMATSU PHOTONICS K.K.
|
Family ID: |
39930660 |
Appl. No.: |
11/812234 |
Filed: |
June 15, 2007 |
Current U.S.
Class: |
250/361C ;
430/274.1 |
Current CPC
Class: |
G01T 1/202 20130101;
G03B 42/02 20130101 |
Class at
Publication: |
250/361.C ;
430/274.1 |
International
Class: |
G03C 1/00 20060101
G03C001/00; G01T 1/20 20060101 G01T001/20 |
Claims
1. A radiation image conversion panel comprising: an aluminum
substrate; an aluminum oxide layer formed on a surface of the
aluminum substrate; a chromium layer covering the aluminum oxide
layer, at least a portion of the aluminum oxide layer being
positioned between the aluminum substrate and the chromium layer; a
metal film, provided on the chromium layer, having a light
reflectivity, at least a portion of the chromium layer being
positioned between the aluminum oxide layer and the metal film; an
oxide layer covering the metal film and having a light
transparency, at least a portion of the metal film being positioned
between the chromium layer and the oxide layer; a protective film
covering the oxide layer and having a light transparency, at least
a portion of the oxide layer being positioned between the metal
film and the protective film; and a converting part provided on the
protective film and adapted to convert a radiation image, the
converting part comprising a light emitting surface of the
radiation image conversion panel, and at least a portion of the
protective film being positioned between the oxide layer and the
converting part.
2. A scintillator panel comprising: an aluminum substrate
comprising a radiation receiving surface of the scintillator panel;
an aluminum oxide layer formed on a surface of the aluminum
substrate other than the radiation receiving surface; a chromium
layer covering the aluminum oxide layer, at least a portion of the
aluminum oxide layer being positioned between the aluminum
substrate and the chromium layer; a metal film, provided on the
chromium layer, having a radiation transparency and a light
reflectivity, at least a portion of the chromium layer being
positioned between the aluminum oxide layer and the metal film; an
oxide layer covering the metal film and having a radiation
transparency and a light transparency, at least a portion of the
metal film being positioned between the chromium layer and the
oxide layer; a protective film covering the oxide layer and having
a radiation transparency and a light transparency, at least a
portion of the oxide layer being positioned between the metal film
and the protective film; and a scintillator provided on the
protective film, the scintillator comprising a light emitting
surface of the scintillator panel, and at least a portion of the
protective film being positioned between the oxide layer and the
scintillator.
3. A scintillator panel according to claim 2, further comprising a
radiation-transparent reinforcement plate bonded to the aluminum
substrate, the aluminum substrate being arranged between the
reinforcement plate and the scintillator.
4. A radiation image sensor comprising: a radiation image
conversion panel including an aluminum substrate; an aluminum oxide
layer formed on a surface of the aluminum substrate; a chromium
layer covering the aluminum oxide layer, at least a portion of the
aluminum oxide layer being positioned between the aluminum
substrate and the chromium layer; a metal film, provided on the
chromium layer, having a light reflectivity, at least a portion of
the chromium layer being positioned between the aluminum oxide
layer and the metal film; an oxide layer covering the metal film
and having a light transparency, at least a portion of the metal
film being positioned between the chromium layer and the oxide
layer; a protective film covering the oxide layer and having a
light transparency, at least a portion of the oxide layer being
positioned between the metal film and the protective film; and a
converting part provided on the protective film and adapted to
convert a radiation image, the converting part comprising a light
emitting surface of the radiation image conversion panel, and at
least a portion of the protective film being positioned between the
oxide layer and the converting part; and an image pickup device for
converting light emitted from the light emitting surface of the
converting part of the radiation image conversion panel into an
electric signal.
5. A scintillator panel according to claim 3, wherein the
reinforcement plate is larger than the scintillator when seen in
the thickness direction of the aluminum substrate.
6. A scintillator panel according to claim 3, wherein the thickness
of the reinforcement plate is greater than the total thickness of
the aluminum substrate and the aluminum oxide layer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a radiation image
conversion panel, a scintillator panel, and a radiation image
sensor which are used in medical and industrial x-ray imaging and
the like.
[0003] 2. Related Background Art
[0004] While x-ray sensitive films have conventionally been in use
for medical and industrial x-ray imaging, radiation imaging systems
using radiation detectors have been coming into widespread use from
the viewpoint of their convenience and storability of imaging
results. In such a radiation imaging system, pixel data formed by
two-dimensional radiations are acquired by a radiation detector as
an electric signal, which is then processed by a processor, so as
to be displayed on a monitor.
[0005] Known as a typical radiation detector is one having a
structure bonding a radiation image conversion panel (which will be
referred to as "scintillator panel" in the following as the case
may be), in which a scintillator for converting a radiation into
visible light is formed on a substrate such as aluminum, glass, or
fused silica, to an image pickup device. In this radiation
detector, a radiation incident thereon from the substrate side is
converted into light by the scintillator, and thus obtained light
is detected by the image pickup device.
[0006] In the radiation image conversion panels disclosed in
Japanese Patent Application Laid-Open Nos. 2006-113007 and HEI
4-118599, a stimulable phosphor is formed on an aluminum substrate
having a surface formed with an alumite layer. The radiation image
conversion panel having a stimulable phosphor formed on a substrate
will be referred to as "imaging plate" in the following as the case
may be.
SUMMARY OF THE INVENTION
[0007] In the above-mentioned radiation image conversion panel,
however, the alumite layer has a low reflectance for the light
emitted from a scintillator or a phosphor such as stimulable
phosphor, whereby the radiation image conversion panel may fail to
attain a sufficiently high luminance. Also, cracks, pinholes, and
the like may be formed in the alumite layer by the heat generated
when vapor-depositing the scintillator or stimulable phosphor onto
the aluminum substrate, for example. As a result, the aluminum
substrate and an alkali halide scintillator or stimulable phosphor
may react with each other, thereby corroding the aluminum
substrate. Though resistant against the corrosion, the alumite
layer may corrode by reacting with the scintillator. The corrosion
affects resulting images. Even if only a minute point is corroded,
the reliability of a captured image utilized for an image analysis
will deteriorate. The corrosion may increase as time passes.
Further, the surface flatness of the alumite layer is lower than
that of the aluminum substrate, whereby the scintillator panel may
fail to attain a sufficient flatness. While the radiation image
conversion panel is required to have uniform luminance and
resolution characteristics within the substrate surface, the
substrate is harder to manufacture as it is larger in size.
[0008] In view of the circumstances mentioned above, it is an
object of the present invention to provide a radiation image
conversion panel, a scintillator panel, and a radiation image
sensor which can prevent aluminum substrates from corroding, while
having a high flatness and a high luminance.
[0009] For solving the problem mentioned above, the radiation image
conversion panel in accordance with the present invention comprises
an aluminum substrate; an alumite layer formed on a surface of the
aluminum substrate; a chromium layer covering the alumite layer; a
metal film, provided on the chromium layer, having a radiation
transparency and a light reflectivity; an oxide layer covering the
metal film and having a radiation transparency and a light
transparency; a protective film covering the metal film and having
a radiation transparency and a light transparency; and a converting
part provided on the protective film and adapted to convert a
radiation image.
[0010] The scintillator panel in accordance with the present
invention comprises an aluminum substrate; an alumite layer formed
on a surface of the aluminum substrate; a chromium layer covering
the alumite layer; a metal film, provided on the chromium layer,
having a radiation transparency and a light reflectivity; an oxide
layer covering the metal film and having a radiation transparency
and a light transparency; a protective film covering the metal film
and having a radiation transparency and a light transparency; and a
scintillator provided on the protective film.
[0011] The radiation image sensor in accordance with the present
invention comprises a radiation image conversion panel including an
aluminum substrate, an alumite layer formed on a surface of the
aluminum substrate, a chromium layer covering the alumite layer, a
metal film which is provided on the chromium layer and has a
radiation transparency and a light reflectivity, an oxide layer
covering the metal film and having a radiation transparency and a
light transparency, a protective film covering the metal film and
having a radiation transparency and a light transparency, and a
converting part provided on the protective film and adapted to
convert a radiation image; and an image pickup device for
converting light emitted from the converting part of the radiation
image conversion panel into an electric signal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a partly broken perspective view schematically
showing a scintillator panel in accordance with a first
embodiment;
[0013] FIG. 2 is a sectional view taken along the line II-II shown
in FIG. 1;
[0014] FIG. 3 is a graph showing an example of AES spectrum of the
alumite layer in the scintillator panel in accordance with the
first embodiment;
[0015] FIG. 4 is a graph showing an example of AES spectrum of the
metal film in the scintillator panel in accordance with the first
embodiment;
[0016] FIGS. 4A to 4C are process sectional views schematically
showing an example of the method of manufacturing a scintillator
panel in accordance with the first embodiment;
[0017] FIGS. 5A to 5D are process sectional views schematically
showing the example of the method of manufacturing a scintillator
panel in accordance with the first embodiment;
[0018] FIG. 7 is a diagram showing an example of radiation image
sensor including the scintillator panel in accordance with the
first embodiment;
[0019] FIG. 8 is a view showing another example of radiation image
sensor including the scintillator panel in accordance with the
first embodiment; and
[0020] FIG. 9 is a sectional view schematically showing the
scintillator panel in accordance with a second embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] In the following, preferred embodiments of the present
invention will be explained in detail with reference to the
accompanying drawings. For easier understanding of the explanation,
the same constituents in the drawings will be referred to with the
same numerals whenever possible while omitting their overlapping
descriptions. The dimensions of the drawings include parts
exaggerated for explanations and do not always match dimensional
ratios in practice.
First Embodiment
[0022] FIG. 1 is a partly broken perspective view showing a
scintillator panel (an example of radiation image conversion panel)
in accordance with a first embodiment. FIG. 2 is a sectional view
taken along the line II-II shown in FIG. 1. As shown in FIGS. 1 and
2, the scintillator panel 10 comprises an aluminum substrate 12, an
alumite layer 14 formed on a surface of the aluminum substrate 12,
and a chromium layer 16 (intermediate film) covering the alumite
layer 14. The alumite layer 14 and chromium layer 16 are in close
contact with each other. The scintillator panel 10 also includes a
metal film 18 which is provided on the chromium layer 16 and has a
radiation transparency and a light reflectivity, an oxide layer 20
covering the metal film 18 and having a radiation transparency and
a light transparency, a protective film 22 covering the oxide layer
20 and having a radiation transparency and a light transparency,
and a scintillator 24 (an example of a converting part adapted to
convert a radiation image) provided on the protective film 22. The
chromium layer 16, metal film 18, oxide layer 20, protective film
22, and scintillator 24 are in close contact with each other.
[0023] In this embodiment, the aluminum substrate 12, alumite layer
14, chromium layer 16, metal film 18, and oxide layer 20 are
totally sealed with the protective film 22. The protective film 22
prevents the metal film 18 from corroding because of pinholes and
the like formed in the oxide layer 20. Also, the aluminum substrate
12, alumite layer 14, chromium layer 16, metal film 18, oxide layer
20, protective film 22, and scintillator 24 are totally sealed with
a protective film 26.
[0024] When a radiation 30 such as x-ray is incident on the
scintillator 24 from the aluminum substrate 12 side, light 32 such
as visible light is emitted from the scintillator 24. Therefore,
when a radiation image is incident on the scintillator panel 10,
the scintillator 24 converts the radiation image into a light
image. The radiation 30 successively passes through the protective
film 26, protective film 22, aluminum substrate 12, alumite layer
14, chromium layer 16, metal film 18, oxide layer 20, and
protective film 22, thereby reaching the scintillator 24. The light
32 emitted from the scintillator 24 is released through the
protective film 26 to the outside, while passing through the
protective film 22, so as to be reflected by the metal film 18 and
oxide layer 20 to the outside. The scintillator panel 10 is used
for medical and industrial x-ray imaging and the like.
[0025] The aluminum substrate 12 is a substrate mainly made of
aluminum, but may contain impurities and the like. Preferably, the
thickness of the aluminum substrate 12 is 0.3 to 1.0 mm. When the
thickness of the aluminum substrate 12 is less than 0.3 mm, the
scintillator 24 tends to be easy to peel off as the aluminum
substrate 12 bends. When the thickness of the aluminum substrate 12
exceeds 1.0 mm, the transmittance of the radiation 30 tends to
decrease.
[0026] The alumite layer 14 is formed by anodic oxidation of
aluminum, and is made of a porous aluminum oxide. The alumite layer
14 makes it harder to damage the aluminum substrate 12. If the
aluminum substrate 12 is damaged, the reflectance of the aluminum
substrate 12 will be less than a desirable value, whereby no
uniform reflectance will be obtained within the surface of the
aluminum substrate 12. Whether the aluminum substrate 12 is damaged
or not can be inspected visually, for example. The alumite layer 14
may be formed on the aluminum substrate 12 on only one side to be
formed with the scintillator 24, on both sides of the aluminum
substrate 12, or such as to cover the aluminum substrate 12 as a
whole. Forming the alumite layer 14 on both sides of the aluminum
substrate 12 can reduce the warpage and flexure of the aluminum
substrate 12, and thus can prevent the scintillator 24 from being
unevenly vapor-deposited. Forming the alumite layer 14 can also
erase streaks occurring when forming the aluminum substrate 12 by
rolling. Therefore, even when a reflecting film (metal film 18 and
oxide layer 20) is formed on the aluminum substrate 12, a uniform
reflectance can be obtained within the surface of the aluminum
substrate 12 in the reflecting film. Preferably, the thickness of
the alumite layer 14 is 10 to 5000 nm. When the thickness of the
alumite layer 14 is less than 10 nm, the damage prevention effect
of the aluminum substrate 12 tends to decrease. When the thickness
of the alumite layer 14 exceeds 5000 nm, the alumite layer 14 tends
to peel off in particular in corner parts of the aluminum substrate
12, thereby causing large cracks in the alumite layer 14 and
deteriorating the moisture resistance of the alumite layer 14. In
one example, the thickness of the alumite layer 14 is 1000 nm. The
thickness of the alumite layer 14 is appropriately determined
according to the size and thickness of the aluminum substrate
12.
[0027] FIG. 3 is a graph showing an example of AES spectrum of the
alumite layer in the scintillator panel in accordance with the
first embodiment. This example conducts an element analysis in the
thickness direction of the alumite layer 14 by sputter-etching the
alumite layer 14 with argon ions for 31 minutes. In this case,
aluminum, oxygen, and argon are detected. Here, argon derives from
the argon ions at the time of sputter etching, and thus is not an
element contained in the alumite layer 14. Therefore, the alumite
layer 14 in this example contains aluminum and oxygen.
[0028] Reference will be made to FIGS. 1 and 2 again. The chromium
layer 16 is a layer mainly made of chromium, but may contain
impurities and the like. The chromium layer 16 may also be made of
a chromium compound. Preferably, the chromium layer 16 has a
thickness of 50 to 1000 nm. In one example, the thickness of the
chromium layer 16 is 200 nm. The chromium layer 16 reduces minute
irregularities of the alumite layer 14, thereby advantageously
acting for forming the metal film 18 having a uniform thickness on
the alumite layer 14.
[0029] The protective films 22 and 26 are organic or inorganic
films, which may be made of materials different from each other or
the same material. The protective films 22 and 26 are made of
polyparaxylylene, for example, but may also be of xylylene-based
materials such as polymonochloroparaxylylene,
polydichloroparaxylylene, polytetrachloroparaxylylene,
polyfluoroparaxylylene, polydimethylparaxylylene, and
polydiethylparaxylylene. The protective films 22 and 26 may be made
of polyurea, polyimide, and the like, for example, or inorganic
materials such as LiF, MgF.sub.2, SiO.sub.2, Al.sub.2O.sub.3,
TiO.sub.2, MgO, and SiN. The protective films 22 and 26 may also be
formed by combining inorganic and organic films. In one example,
the protective films 22 and 26 have a thickness of 10 .mu.m
each.
[0030] The metal film 18 is constructed by Al, for example, but may
also be made of Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, Au, or the like.
Among them, Al or Ag is preferred. The metal film 18 may also
contain elements such as oxygen other than metal elements. The
metal film 18 may be constituted by a plurality of metal films,
e.g., a Cr film and an Au film provided on the Cr film. Preferably,
the thickness of the metal film 18 is 50 to 200 nm. In one example,
the thickness of the metal film 18 is 70 nm. When an aluminum film
is used as the metal film 18, it may be analyzed by AES (Auger
Electron Spectroscopy) as an incomplete aluminum oxide depending on
the vapor deposition condition and the processing after the vapor
deposition.
[0031] FIG. 4 is a graph showing an example of AES spectrum of the
metal film in the scintillator panel in accordance with the first
embodiment. This example conducts an element analysis in the
thickness direction of the metal layer 18 by sputter-etching the
metal film 18 with argon ions for 20 minutes. In this case,
aluminum, oxygen, and argon are detected. Here, argon derives from
the argon ions at the time of sputter etching, and is not an
element contained in the metal film 18. Though containing oxygen,
the metal film 18 can clearly be distinguished from the alumite
layer 14 in view of their AES spectra forms.
[0032] Reference will be made to FIGS. 1 and 2 again. The oxide
layer 20 is made of a metal oxide, SiO.sub.2, TiO.sub.2, or the
like, for example. The oxide layer 20 may be constituted by a
plurality of oxide layers made of materials different from each
other, e.g., an SiO.sub.2 film and a TiO.sub.2 film. In one
example, the thickness of the SiO.sub.2 film is 80 nm while the
thickness of the TiO.sub.2 film is 50 nm. The thickness and number
of laminated layers of the SiO.sub.2 and TiO.sub.2 films are
determined in view of the reflectance for the wavelength of light
32 emitted from the scintillator 24. The oxide layer 20 also
functions to prevent the metal film 18 from corroding.
[0033] The scintillator 24 is smaller than the aluminum film 12
when seen in the thickness direction of the aluminum substrate 12.
For example, the scintillator 24 is constituted by a phosphor which
converts the radiation into visible light, and is made of a
columnar crystal or the like of CsI doped with Ti, Na, or the like.
The scintillator 24 has a structure provided with a forest of
columnar crystals. The scintillator 24 may also be made of Ti-doped
NaI, Ti-doped KI, or Eu-doped LiI. A stimulable phosphor such as
Eu-doped CsBr may be used in place of the scintillator 24. The
thickness of the scintillator 24 is preferably 100 to 1000 .mu.m,
more preferably 450 to 550 .mu.m. Preferably, the average column
diameter of the columnar crystals constituting the scintillator 24
is 3 to 10 .mu.m.
[0034] As explained in the foregoing, the scintillator panel 10
comprises the aluminum substrate 12; the alumite layer 14 formed on
the surface of the aluminum substrate 12; the chromium layer 16
covering the alumite layer 14; the metal film 18, provided on the
chromium layer 16, having a radiation transparency and a light
reflectivity; the oxide layer 20 covering the metal layer 18 and
having a radiation transparency and a light transparency; the
protective film 22 covering the oxide layer 20 and having a
radiation transparency and a light transparency; and the
scintillator 24 provided on the protective film 22. Since the
protective film 22 is provided between the alumite layer 14 and
scintillator 24, the aluminum substrate 12 and scintillator 24 can
be kept from reacting with each other even if the alumite layer 14
is formed with cracks, pinholes, and the like. As a consequence,
the aluminum substrate 12 can be prevented from corroding. Since
the light 32 emitted from the scintillator 24 is reflected by the
metal film 18 and oxide layer 20, a high luminance can be obtained.
Since the chromium layer 16 is provided between the alumite layer
14 and metal film 18, the adhesion between the alumite layer 14 and
metal film 18 improves, while the flatness of the metal film 18 can
be enhanced. Forming the alumite layer 14 can further erase damages
to the surface of the aluminum substrate 12, whereby uniform
luminance and resolution characteristics can be obtained within the
surface of the scintillator panel 10.
[0035] FIGS. 4A to 4C and 5A to 5D are process sectional views
schematically showing an example of the method of manufacturing a
scintillator panel in accordance with the first embodiment. The
method of manufacturing the scintillator panel 10 will now be
explained with reference to FIGS. 4A to 4C and 5A to 5D.
[0036] First, as shown in FIG. 4A, the aluminum substrate 12 is
prepared. Subsequently, as shown in FIG. 4B, the alumite layer 14
is formed by anodic oxidation on a surface of the aluminum
substrate 12. For example, the aluminum substrate 12 is
electrolyzed by an anode in an electrolyte such as dilute sulfuric
acid, so as to be oxidized. This forms the alumite layer 14
constituted by an assembly of hexagonal columnar cells each having
a fine hole at the center. The alumite layer 14 may be dipped in a
dye, so as to be colored. This can improve the resolution or
enhance the luminance. After being formed, the alumite layer 14 is
subjected to a sealing process for filling the fine holes.
[0037] Next, as shown in FIG. 4C, the chromium layer 16 is formed
on the alumite layer 14 by vapor deposition. Further, as shown in
FIG. 5A, the metal film 18 is formed on the chromium layer 16 by
using vacuum vapor deposition. Thereafter, as shown in FIG. 5B, the
oxide layer 20 is formed on the metal film 18. Next, as shown in
FIG. 5C, the protective film 22 is formed by using CVD so as to
seal the aluminum substrate 12, alumite layer 14, chromium layer
16, metal film 18, and oxide layer 20 as a whole. Further, as shown
in FIG. 5D, the scintillator 24 is formed on the protective film 22
on the oxide layer 20 by using vapor deposition. Subsequently, as
shown in FIGS. 1 and 2, the protective film 26 is formed by using
CVD so as to seal the aluminum substrate 12, alumite layer 14,
chromium layer 16, metal film 18, oxide layer 20, protective film
22, and scintillator 24 as a whole. Thus, the scintillator panel 10
is manufactured. The sealing with the protective films 22 and 26
can be realized by lifting the side of the aluminum substrate 12
opposite from the scintillator forming surface from a substrate
holder at the time of CVD. An example of such method is one
disclosed in U.S. Pat. No. 6,777,690. This method lifts the
aluminum substrate 12 by using pins. In this case, no protective
film is formed on minute contact surfaces between the aluminum
substrate 12 and the pins.
[0038] FIG. 7 is a diagram showing an example of radiation image
sensor including the scintillator panel in accordance with the
first embodiment. The radiation image sensor 100 shown in FIG. 7
comprises the scintillator panel 10 and an image pickup device 70
which converts the light 32 emitted from the scintillator 24 of the
scintillator panel 10 into an electric signal. The light 32 emitted
from the scintillator 24 is reflected by a mirror 50, so as to be
made incident on a lens 60. The light 32 is converged by the lens
60, so as to be made incident on the image pickup device 70. One or
a plurality of lenses 60 may be provided.
[0039] The radiation 30 emitted from a radiation source 40 such as
x-ray source is transmitted through an object to be inspected which
is not depicted. The transmitted radiation image is made incident
on the scintillator 24 of the scintillator panel 10. As a
consequence, the scintillator 24 emits a visible light image (the
light 32 having a wavelength to which the image pickup device 70 is
sensitive) corresponding to the radiation image. The light 32
emitted from the scintillator 24 is made incident on the image
pickup device 70 by way of the mirror 50 and lens 60. For example,
CCDs, flat panel image sensors, and the like can be used as the
image pickup device 70. Thereafter, an electronic device 80
receives the electric signal from the image pickup device 70,
whereby the electric signal is transmitted to a workstation 90
through a lead 36. The workstation 90 analyzes the electric signal,
and outputs an image onto a display.
[0040] The radiation image sensor 100 comprises the scintillator
panel 10 and the image pickup device 70 adapted to convert the
light 32 emitted from the scintillator 24 of the scintillator panel
10 into the electric signal. Therefore, the radiation image sensor
100 can prevent the aluminum substrate 12 from corroding, while
having a high flatness and a high luminance.
[0041] FIG. 8 is a view showing another example of radiation image
sensor including the scintillator panel in accordance with the
first embodiment. The radiation image sensor 100a shown in FIG. 8
comprises the scintillator panel 10, and an image pickup device 70
which is arranged so as to oppose the scintillator panel 10 and
adapted to convert light emitted from the scintillator 24 into an
electric signal. The scintillator 24 is arranged between the
aluminum substrate 12 and image pickup device 70. The
light-receiving surface of the image pickup device 70 is arranged
on the scintillator 24 side. The scintillator panel 10 and image
pickup device 70 may be joined together or separated from each
other. When joining them, an adhesive may be used, or an optical
coupling material (refractive index matching material) may be
utilized so as to reduce the loss of the emitted light 32 in view
of the refractive indexes of the scintillator 24 and protective
film 26.
[0042] The radiation image sensor 100a comprises the scintillator
panel 10 and the image pickup device 70 adapted to convert the
light 32 emitted from the scintillator 24 of the scintillator panel
10 into the electric signal. Therefore, the radiation image sensor
100a can prevent the aluminum substrate 12 from corroding, while
having a high flatness and a high luminance.
Second Embodiment
[0043] FIG. 9 is a sectional view schematically showing the
scintillator panel in accordance with a second embodiment. The
scintillator panel 10a shown in FIG. 9 further comprises a
radiation-transparent reinforcement plate 28 bonded to the aluminum
substrate 12 in addition to the structure of the scintillator panel
10. The aluminum substrate 12 is arranged between the reinforcement
plate 28 and scintillator 24.
[0044] The reinforcement plate 28 is bonded to the aluminum
substrate 12 by a double-sided adhesive tape, an adhesive, or the
like, for example. Employable as the reinforcement plate 28 are (1)
carbon fiber reinforced plastics (CFRP), (2) carbon boards (made by
carbonizing and solidifying charcoal and paper), (3) carbon
substrates (graphite substrates), (4) plastic substrates, (5)
sandwiches of thinly formed substrates (1) to (4) mentioned above
with resin foam, and the like. Preferably, the thickness of the
reinforcement plate 28 is greater than the total thickness of the
aluminum substrate 12 and alumite layer 14. This improves the
strength of the scintillator panel 10e as a whole. Preferably, the
reinforcement plate 28 is larger than the scintillator 24 when seen
in the thickness direction of the aluminum substrate 12. Namely, it
will be preferred if the reinforcement plate 28 hides the
scintillator 24 when seen in the thickness direction of the
aluminum substrate 12 from the reinforcement plate 28 side. This
can prevent a shadow of the reinforcement plate 28 from being
projected. In particular, this can prevent an image from becoming
uneven because of the shadow of the reinforcement plate 28 when the
radiation image 30 having a low energy is used.
[0045] The scintillator panel 10a not only exhibits the same
operations and effects as those of the scintillator panel 10, but
can further improve the flatness and rigidity of the scintillator
panel 10a. Therefore, the scintillator panel 10e can prevent the
scintillator 24 from peeling off as the aluminum substrate 12
bends. Since the radiation image sensor 100 shown in FIG. 7 uses
the scintillator panel as a single unit, it is effective to employ
the scintillator panel 10a having a high rigidity.
[0046] Though preferred embodiments of the present invention are
explained in detail in the foregoing, the present invention is not
limited to the above-mentioned embodiments and the structures
exhibiting various operations and effects mentioned above.
[0047] For example, the radiation image sensors 100, 100a may
employ the scintillator panel 10a in place of the scintillator
panel 10.
[0048] The scintillator panels 10, 10a may be free of the
protective film 26.
[0049] Though the above-mentioned embodiments exemplify the
radiation image conversion panel by the scintillator panel, a
stimulable phosphor (an example of a converting part adapted to
convert a radiation image) may be used in place of the scintillator
24, whereby an imaging plate as the radiation image conversion
panel can be made. The stimulable phosphor converts the radiation
image into a latent image. This latent image is scanned with laser
light, so as to read a visible light image. The visible light image
is detected by a detector (photosensor such as line sensor, image
sensor, and photomultiplier).
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