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Claims  |
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I claim:
1. A radiation image read-out and reproducing method characterized by steps
of
mounting at least one stimulable phosphor sheet carrying a radiation image
stored thereon and at least one recording medium for reproducing a
radiation image as a visible image respectively on first and second rotary
plates,
projecting a stimulating light beam onto the stimulable phosphor sheet
while the first rotary plate is rotated, thereby effecting main scanning
of the sheet by the stimulating light beam and the stimulating light beam
is moved relative to the first rotary plate in a radial direction of the
first rotary plate, thereby effecting sub-scanning of the sheet by the
stimulating light beam,
photoelectrically detecting light emitted by the stimulable phosphor sheet
upon stimulation by the stimulating light beam by a photoelectric
converter means, thereby obtaining an electric image signal representing
the radiation image stored on the stimulable phosphor sheet,
projecting a recording light beam modulated on the basis of the electric
image signal onto the recording medium while the second rotary plate is
rotated in synchronization with the main scanning of the recording medium
by the stimulating light beam, thereby effecting main scanning of the
recording medium by the recording light beam, moving the recording light
beam relative to the second rotary plate in a radial direction of the
second rotary in synchronization with the sub-scanning of the stimulable
phosphor sheet by the stimulating light beam, thereby effecting
sub-scanning of the recording medium by the recording light beam, and
thus recording the radiation image on the recording medium simultaneously
with read-out of the radiation image stored on the stimulable phosphor
sheet.
2. A radiation image read-out and reproducing method as defined in claim 1
characterized in that the direction in which the first rotary plate is
rotated with respect to the stimulating light beam is the same as the
direction in which the second rotary plate is rotated with respect to the
recording light beam.
3. A radiation image read-out and reproducing method as defined in claim 1
characterized in that the direction in which the first rotary plate is
rotated with respect to the stimulating light beam is opposite to the
direction in which the second rotary plate is rotated with respect to the
recording light beam.
4. A radiation image read-out and reproducing method as defined in claim 1
in which said stimulable phosphor sheet is mounted on the first rotary
plate so that the center of gravity of the sheet coincides with the center
of rotation of the first rotary plate.
5. A radiation image read-out and reproducing method as defined in claim 4
in which a plurality of stimulable phosphor sheets are mounted on the
first rotary plate to surround the center of rotation of the first rotary
plate.
6. A radiation image read-out and reproducing method as defined in claim 1
in which said recording medium is mounted on the second rotary plate so
that the center of gravity of the recording medium coincides with the
center of rotation of the second rotary plate.
7. A radiation image read-out and reproducing method as defined in claim 6
in which a plurality of recording media are mounted on the second rotary
plate to surround the center of rotation of the second rotary plate.
8. A radiation image read-out and reproducing method as defined in claim 1
in which said main scanning of the stimulable phosphor sheet is effected
at a constant linear velocity.
9. A radiation image read-out and reproducing method as defined in claim 1
in which the rotation of the first rotary plate for the main scanning of
the stimulable phosphor sheet is the same in phase as that of the second
rotary plate for the main scanning of the recording medium.
10. A radiation image read-out and reproducing method as defined in claim 1
in which said sub-scanning of the stimulable phosphor sheet is effected by
moving the stimulating light beam in a radial direction of the first
rotary plate with the first rotary plate being fixed.
11. A radiation image read-out and reproducing method as defined in claim 1
in which said sub-scanning of the stimulable phosphor sheet is effected by
moving the first rotary plate in a radial direction thereof with the
stimulating light beam being fixed.
12. A radiation image read-out and reproducing method as defined in claim 1
in which said sub-scanning of the recording medium is effected by moving
the recording light beam in a radial direction of the second rotary plate
with the second rotary plate being fixed.
13. A radiation image read-out and reproducing method as defined in claim 1
in which said sub-scanning of the recording medium is effected by moving
the second rotary plate in a radial direction thereof with the recording
light beam being fixed.
14. A radiation image read-out and reproducing method characterized by
steps of
mounting at least one stimulable phosphor sheet carrying a radiation image
stored thereon and at least one recording medium for reproducing a
radiation image as a visible image respectively on first and second rotary
plates which are mounted on the same rotational shaft to be rotated
integrally with each other,
projecting a stimulating light beam and a recording light beam respectively
onto the stimulable phosphor sheet and the recording medium while the
first and second rotary plates are rotated integrally with each other,
thereby effecting main scanning of the sheet and the recording medium by
the respective light beams, the distance and the direction by which and in
which the recording light beam projecting position is spaced from the
center of rotation of the second rotary plate being equal to those by
which and in which the stimulating light beam projecting position is
spaced from the center of rotation of the first rotary plate, and the
stimulating light beam and the recording light beam are moved relative to
the first and second rotary plates in a radial direction of the respective
rotary plates, thereby effecting sub-scanning of the sheet and the
recording medium by the respective light beams,
photoelectrically detecting light emitted by the stimulable phosphor sheet
upon stimulation by the stimulating light beam by a photoelectric
converter means, thereby obtaining an electric image signal representing
the radiation image stored on the stimulable phosphor sheet, modulating
said recording light on the basis of the electric image signal, and
thus recording the radiation image on the recording medium simultaneously
with read-out of the radiation image stored on the stimulable phosphor
sheet.
15. A radiation image read-out and reproducing method as defined in claim
14 in which said first and second rotary plates are united into a single
rotary plate and said stimulable phosphor sheet is mounted on one side of
the single rotary plate while the recording medium is mounted on the other
side of the same.
16. A radiation image read-out and reproducing method as defined in claim
15 in which the stimulating light projecting position and the recording
light beam projecting position are opposed to each other with the single
rotary plate intervening therebetween.
17. A radiation image read-out and reproducing method as defined in claim
14 in which said stimulable phosphor sheet is mounted on the first rotary
plate so that the center of gravity of the sheet coincides with the center
of rotation of the first rotary plate.
18. A radiation image read-out and reproducing method as defined in claim
17 in which a plurality of stimulable phosphor sheets are mounted on the
first rotary plate to surround the center of rotation of the first rotary
plate.
19. A radiation image read-out and reproducing method as defined in claim
14 in which said recording medium is mounted on the second rotary plate so
that the center of gravity of the recording medium coincides with the
center of rotation of the second rotary plate.
20. A radiation image read-out and reproducing method as defined in claim
19 in which a plurality of recording media are mounted on the second
rotary plate to surround the center of rotation of the second rotary
plate.
21. A radiation image read-out and reproducing method as defined in claim
14 in which said main scanning of the stimulable phosphor sheet is
effected at a constant linear velocity.
22. A radiation image read-out and reproducing method as defined in claim
14 in which said sub-scanning of the stimulable phosphor sheet and the
recording medium is effected by moving the stimulating light beam and the
recording light beam in a radial direction of the corresponding rotary
plates with the respective rotary plates being fixed.
23. A radiation image read-out and reproducing method as defined in claim
14 in which said sub-scanning of the stimulable phosphor sheet and the
recording medium is effected by moving the corresponding rotary plates in
a radial direction thereof with the respective light beams being fixed.
24. A radiation image read-out and reproducing method characterized by
steps of
mounting at least one stimulable phosphor sheet carrying a radiation image
stored thereon and at least one recording medium adapted to recording the
radiation image as a visible image on a rotary plate rotatable about a
rotational axis so that the recording surfaces the stimulable phosphor
sheet and the recording medium face in opposite directions,
projecting a stimulating light beam onto the stimulable phosphor sheet
while a recording light beam is projected onto the recording medium to
impinge upon the recording medium in a position which is equal in
direction and distance from the rotational axis of the rotary plate to the
stimulating light beam projecting position on the stimulable phosphor
sheet in which the stimulating light beam impinges upon the stimulable
phosphor sheet,
main scanning of the stimulable phosphor sheet by the stimulating light
beam and main scanning of the recording medium by the recording light beam
being effected by rotating the rotary plate during projection of the
stimulating light beam and the recording light beam, sub-scanning of the
stimulable phosphor sheet by the stimulating light beam and sub-scanning
of the recording medium by the recording light beam being effected by
moving the stimulating light beam and the recording light beam relative to
the rotary plate in a radial direction of the rotary plate,
measuring the surface wobble of the rotary plate due to the rotation
thereof, controlling the stimulating light beam and the recording light
beam to correctly focus respectively on the stimulable phosphor sheet and
the recording medium on the basis of the result of the measurement while
the stimulable phosphor sheet and the recording medium are scanned by the
respective light beams,
photoelectrically detecting light emitted by the stimulable phosphor sheet
upon stimulation by the stimulating light beam by a photoelectric
converter means, thereby obtaining an electric image signal representing
the radiation image stored on the stimulable phosphor sheet, modulating
said recording light on the basis of the electric image signal, and
thus recording the radiation image on the recording medium simultaneously
with read-out of the radiation image stored on the stimulable phosphor
sheet.
25. A radiation image read-out and reproducing method as defined in claim
24 in which said surface wobble of the rotary plate is measured by
projecting a measuring light onto the rotary plate and detecting reflected
light from the rotary plate.
26. A radiation image read-out and reproducing method as defined in claim
25 in which said reflected light is detected by a quadra-photodiode.
27. A radiation image read-out and reproducing method as defined in claim
24 in which said stimulable phosphor sheet and the recording medium are
mounted on the rotary plate so that the respective centers of gravity of
thereof coincides with the center of rotation of the rotary plate.
28. A radiation image read-out and reproducing method as defined in claim
27 in which a plurality of stimulable phosphor sheets and a plurality of
recording media are mounted on the first rotary plate to surround the
center of rotation of the first rotary plate.
29. A radiation image read-out and reproducing method as defined in claim
24 in which said main scanning of the stimulable phosphor sheet is
effected at a constant linear velocity.
30. A radiation image read-out and reproducing method as defined in claim
24 in which said sub-scanning of the stimulable phosphor sheet and the
recording medium is effected by moving the stimulating light beam and the
recording light beam in a radial direction of the corresponding rotary
plates with the respective rotary plates being fixed.
31. A radiation image read-out and reproducing method as defined in claim
24 in which said sub-scanning of the stimulable phosphor sheet and the
recording medium is effected by moving the corresponding rotary plates in
a radial direction thereof with the respective light beams being fixed
32. A radiation image read-out method characterized by steps of
mounting a stimulable phosphor sheet carrying a radiation image stored
thereon on a rotar plate,
projecting a stimulating light beam onto the stimulable phosphor sheet
while the rotary plate is rotated, thereby effecting main scanning of the
sheet by the stimulating light beam and the stimulating light beam is
moved relative to the rotary plate in a radial direction of the first
rotary plate, thereby effecting sub-scanning of the sheet by the
stimulating light beam,
measuring the surface wobble of the rotary plate due to the rotation
thereof, controlling the stimulating light beam to correctly focus on the
stimulable phosphor sheet on the basis of the result of the measurement
while the stimulable phosphor sheet is scanned by the stimulating light
beam, and
photoelectrically detecting light emitted by the stimulable phosphor sheet
upon stimulation by the stimulating light beam by a photoelectric
converter means, thereby obtaining radiation image information. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a radiation image read-out and reproducing method
for reading out an image stored on a stimulable phosphor sheet by exposing
the stimulable phosphor sheet to stimulating rays which cause the
stimulable phosphor sheet to emit light in proportion to the stored
radiation energy and photoelectrically detecting the emitted light, and
more particularly to such a method suitable for a relatively small
stimulable phosphor sheet used for testing a small industrial article,
X-ray test of a limited part and the like.
2. Description of the Prior Art
When certain kinds of phosphors are exposed to a radiation such as X-rays,
.alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays,
they store a part of the energy of the radiation. Then when the phosphor
which has been exposed to the radiation is exposed to stimulating rays
such as visible light, light emitted by the phosphor in proportion to the
stored energy of the radiation. A phosphor exhibiting such properties is
referred to as a stimulable phosphor.
A sheet provided with a layer of the stimulable phosphor is referred to as
a stimulable phosphor sheet and is useful for reading out image
information for various purposes.
For example, as disclosed in Japanese Unexamined Patent Publication Nos.
55(1980)-12429, and 56(1981)-11395, it has been proposed to use the
stimulable phosphor sheet in a radiation image recording and reproducing
system. That is, the stimulable phosphor sheet is first exposed to a
radiation passing through an object such as human body to have a radiation
image of the object stored thereon, and is then exposed to stimulating
rays which cause the stimulable phosphor sheet to emit light in proportion
to the stored radiation energy. The light emitted by the stimulable
phosphor sheet upon stimulation thereof is photoelectrically detected and
converted to an electric image signal by a photodetector, and the
radiation image of the object is reproduced as a visible image by use of
the image signal on a recording medium such as a photographic film, a
display device such as a cathode ray tube (CRT), or the like.
However, in the conventional systems, the stimulating rays are caused to
raster-scan the stimulable phosphor sheet in order to read out image
information over a wide range on the sheet, and accordingly, complicated
main scanning and sub scanning are required for stimulation of the sheet
and for detection of the light emitted by the sheet upon stimulation
thereof, whereby the overall system is complicated and becomes large in
size.
The light emitted by the sheet and carrying image information is
photoelectrically detected by a photodetector and delivered to the visible
image reproducing section after converted to an electric signal. When the
radiation image is reproduced as a visible image on a recording medium
such as a photographic film by, for instance, a recording light beam
modulated on the basis of the electric signal, complicated main scanning
and sub scanning are required as in the case of stimulation of the sheet.
This further makes the system large in size and complicated.
On the other hand, since the aforesaid system is very effective for medical
diagnosis, there have been demands towards miniaturization and
simplification of the system and reduction of the manufacturing cost of
the system. If such demands can be met, not only large hospitals but also
consultation rooms of medical practitioners can be equipped with the
system.
In the case that the system is for handling a limited part of the human
body or the like, the stimulable phosphor sheet need not be large in size,
and a small stimulable phosphor sheet suffices for such purposes.
Accordingly, a miniaturized and simplified system for small size
stimulable phosphor sheets will be convenient.
Further, in the case where the stimulable phosphor sheet is used for
non-destructive inspection of small industrial articles, autoradiography
of hybrid formation of DNA colonies or of electrophoresis pattern of
protein, or the like, the effective area of the sheet may be substantially
small. In such cases, it will be preferred that the image read-out and
reproducing system conforms to the small stimulable phosphor sheet in
scale. Further along with miniaturization of the system, there is an
increasing demand for simplification of operation and adjustment of the
system and for reduction of the manufacturing cost.
SUMMARY OF THE INVENTION
In view of the foregoing observations and description, the primary object
of the present invention is to provide a radiation image read-out and
reproducing method for reproducing a radiation image stored on a
stimulable phosphor sheet as a visible image by exposing the stimulable
phosphor sheet to stimulating rays which cause the stimulable phosphor
sheet to emit light in proportion to the stored radiation energy,
photoelectrically detecting the light emitted by the stimulable phosphor
sheet upon stimulation thereof, and reproducing the radiation image as a
visible image on a recording medium by use of an image signal obtained
through the detection, which method enables miniaturization of the system,
simplification of operation and adjustment of the system, and reduction of
the manufacturing cost of the system.
Another object of the present invention is to provide a radiation image
read-out and reproducing method for reproducing a radiation image stored
on a stimulable phosphor sheet as a visible image by exposing the
stimulable phosphor sheet to stimulating rays which cause the stimulable
phosphor sheet to emit light in proportion to the stored radiation energy,
photoelectrically detecting the light emitted by the stimulable phosphor
sheet upon stimulation thereof, and reproducing the radiation image as a
visible image on a recording medium by use of an image signal obtained
through the detection, which method enables miniaturization of the system,
simplification of operation and adjustment of the system, and reduction of
the manufacturing cost of the system without deteriorating the read-out
accuracy of the image information or the recording accuracy of the image
information when forming a visible image on the basis of the image
information.
In accordance with a first aspect of the present invention, there is
provided a radiation image read-out and reproducing method which is a
combination of a radiation image read-out method for reading out a
radiation image stored on a stimulable phosphor sheet and a radiation
image reproducing method for reproducing the radiation image as a visible
image. The read-out method is characterized in that a stimulable phosphor
sheet carrying a radiation image stored thereon is mounted on a first
rotary plate, stimulating rays are projected onto the sheet in the form of
a stimulating light beam while the first rotary plate is rotated to effect
main scanning of the sheet by the stimulating light beam, the stimulating
light beam is moved relative to the first rotary plate in a radial
direction of the first rotary plate to effect sub-scanning of the sheet by
the stimulating light beam, and light emitted by the stimulable phosphor
sheet upon stimulation by the stimulating light beam is photoelectrically
detected by a photoelectric converter means. The radiation image
reproducing method is characterized in that recording light is modulated
on the basis of the image signal obtained in accordance with the read-out
method, the modulated recording light is projected onto a recording medium
mounted on a second rotary plate in the form of a recording light beam
while the second rotary plate is rotated in synchronization with the main
scanning of the recording medium by the stimulating light beam to effect
main scanning of the recording medium by the recording light beam, and the
recording light beam is moved relative to the second rotary plate in a
radial direction of the second rotary plate in synchronization with the
sub-scanning of the stimulable phosphor sheet by the stimulating light
beam to effect subscanning of the recording medium by the recording light
beam, whereby the radiation image is recorded on the recording medium
simultaneously with read-out of the radiation image stored on the
stimulable phosphor sheet.
That is, in accordance with the method, by rotating and linearly moving the
first rotary plate carrying the stimulable phosphor sheet relative to the
stimulating light beam, the stimulating light beam is caused to scan the
stimulable phosphor sheet, thereby reading out the radiation image stored
thereon, and at the same time, by rotating and linearly moving the second
rotary plate carrying a recording medium relative to the recording light
beam in synchronization with the first rotary plate, the recording light
beam is caused to scan the recording medium, thereby recording the
radiation image as a visible on the recording medium. For both the
stimulating light beam and the recording light beam, the main scanning is
effected by rotating the rotary plate and the sub-scanning is radially
moving the light beam relative to the rotary plate.
The radiation image read-out and reproducing method in accordance with a
second aspect of the present invention is characterized in that read-out
of the radiation image stored on the stimulable phosphor sheet and
reproduction of the radiation image as a visible image are carried out by
the use of first and second rotary plates provided on the same rotational
shaft. The read-out method is characterized in that a stimulable phosphor
sheet carrying a radiation image stored thereon is mounted on the first
rotary plate, stimulating rays are projected onto the sheet in the form of
a stimulating light beam while the first rotary plate is rotated to effect
main scanning of the sheet by the stimulating light beam, the stimulating
light beam is moved relative to the first rotary plate in a radial
direction of the first rotary plate to effect sub-scanning of the sheet by
the stimulating light beam, and light emitted by the stimulable phosphor
sheet upon stimulation by the stimulating light beam is photoelectrically
detected by a photoelectric converter means. The radiation image
reproducing method is characterized in that recording light is modulated
on the basis of the image signal obtained in accordance with the read-out
method, the modulated recording light is projected onto a recording medium
mounted on the second rotary plate in the form of a recording light beam
to impinge upon the recording medium in a position having a position
vector from the rotational axis of the second rotary plate equal to the
position vector from the rotational axis of the first rotary plate
representing the stimulating light beam projecting position in which said
stimulating light beam impinges upon the stimulable phosphor sheet while
the second rotary plate is rotated integrally with the first rotary plate
in synchronization with the rotation of the first rotary plate for said
main scanning, thereby effecting main scanning of the recording medium by
the recording light beam, and the recording light beam is moved relative
to the second rotary plate in a radial direction of the second rotary
plate in synchronization with the movement of said stimulating light beam
relative to the stimulable phosphor sheet for said sub-scanning to effect
sub-scanning of the recording medium by the recording light beam, whereby
the radiation image is recorded on the recording medium simultaneously
with read-out of the radiation image stored on the stimulable phosphor
sheet.
That is, in accordance with the method, the radiation image stored on the
stimulable phosphor sheet is recorded on the recording medium as a visible
image by respectively mounting the stimulable phosphor sheet and the
recording medium on the first rotary plate and the second rotary plate
which rotates integrally with the first rotary plate on the same
rotational shaft, and by causing the stimulating light beam and the
recording light beam to respectively scan the stimulable phosphor sheet
and the recording medium by rotating the stimulable phosphor sheet and the
recording medium integrally with each other on the same rotational shaft
and linearly moving them integrally with each other relative to the
stimulating light beam and the recording light beam. The stimulating light
beam projecting position in which the stimulating light beam impinges upon
the stimulable phosphor sheet and the recording light beam projecting
position in which the recording light beam impinges upon the recording
medium are set not to move relative to each other.
Said first and second rotary plates may be spaced from each other or may be
in contact with each other so long as they are on the same rotational
shaft. Further, the method of the present invention also includes the case
where one side of a single rotary plate is used as the first and rotary
plate and the other side of the rotary plate is used as the second rotary
plate.
The radiation image read-out and reproducing method in accordance with a
third aspect of the present invention is characterized in that a
stimulable phosphor sheet carrying a radiation image stored thereon and a
recording medium adapted to recording the radiation image as a visible
image are mounted on a rotary plate rotatable about a rotational axis so
that the recording surfaces thereof face in opposite directions,
stimulating rays are projected onto the stimulable phosphor sheet in the
form of a stimulating light beam while recording light is projected onto
the recording medium in the form of a recording light beam to impinge upon
the recording medium in a position which is equal in direction and
distance from the rotational axis of the rotary plate to the stimulating
light beam projecting position on the stimulable phosphor sheet in which
the stimulating light beam impinges upon the stimulable phosphor sheet,
main scanning of the stimulable phosphor sheet by the stimulating light
beam and main scanning of the recording medium by the recording light beam
are effected by rotating the rotary plate during projection of the
stimulating light beam and the recording light beam, sub-scanning of the
stimulable phosphor sheet by the stimulating light beam and sub-scanning
of the recording medium by the recording light beam are effected by moving
the stimulating light beam and the recording light beam relative to the
rotary plate in a radial direction of the rotary plate, the surface wobble
of the rotary plate due to the rotation thereof is measured, and the
stimulating light beam and the recording light beam are controlled to
correctly focus respectively on the stimulable phosphor sheet and the
recording medium on the basis of the result of the measurement while the
stimulable phosphor sheet and the recording medium are scanned by the
respective light beams.
The stimulating light beam projecting position and the recording light beam
projecting position are set not to move relative to each other.
The stimulable phosphor sheet and the recording medium may be mounted on
the same side of the rotary plate or may be mounted on opposite sides of
the rotary plate.
The surface wobble of the rotary plate may be measured by any measuring
means irrespective of whether it is a contact type or non-contact type.
However, it is preferred that an optical, electrical or magnetical
measuring means be employed in order to stably accomplish the measurement
without being affected by friction between a measuring probe and the
rotary plate.
The stimulating light beam and the recording light beam can be controlled
to correctly focus respectively on the stimulable phosphor sheet and the
recording medium, for instance, by moving an optical element such as the
focusing lens, or the light source along the optical axis.
In the methods in accordance with the first to third aspects of the present
invention, the rotary plate need not be circular in shape but may be of a
polygon substantially symmetrical about the center of rotation thereof.
The term "a radial direction of the rotary plate" means the direction of
the line which passes the center of rotation of the rotary plate and the
light beam projecting position in which the stimulating light beam or the
recording light beam impinges upon the stimulable phosphor sheet or the
recording medium, and along which the stimulating light beam or the
recording light beam is moved.
In accordance with the first aspect of the present invention, the
stimulable phosphor sheet and the recording medium are mounted on rotary
plates and the main scanning of the stimulable phosphor sheet and the
recording medium is effected by rotating the rotary plates. Accordingly,
optical systems such as a galvanometer mirror or a polygonal mirror which
have been used for the main scanning of the stimulable phosphor sheet and
the recording medium in the conventional systems can be eliminated,
whereby the scanning systems can be compactly arranged, and operation and
adjustment of the scanning systems are facilitated. Further, the
manufacturing cost of the scanning systems can be lowered by the cost of
such optical systems.
In accordance wit the second aspect of the present invention, the
stimulable phosphor sheet and the recording medium are mounted on rotary
plates which are arranged to be rotated integrally with each other and the
main scanning of the stimulable phosphor sheet and the recording medium is
effected by rotating the rotary plates. Accordingly, optical systems such
as a galvanometer mirror or a polygonal mirror which have been used for
the main scanning of the stimulable phosphor sheet and the recording
medium in the conventional systems can be eliminated, whereby the scanning
systems can be compactly arranged, and operation and adjustment of the
scanning systems are facilitated. Further, the manufacturing cost of the
scanning systems can be lowered by the cost of such optical systems.
Further, since the stimulating light beam and the recording light beam are
caused to scan the stimulable phosphor sheet and the recording medium by
operating the two rotary plates which are mounted on one rotational axis
to be rotated integrally with each other, both the scanning systems for
read-out and reproduction can be compactly arranged and manufactured at
low cost. Further, since operation for synchronizing the rotary plates
with each other is not required unlike the case where the rotary plates
are independent from each other, operation and adjustment of the scanning
systems are substantially facilitated.
Also in accordance with the third aspect of the present invention, the main
scanning of the stimulable phosphor sheet and the recording medium is
effected by rotating the rotary plate. Accordingly, optical systems such
as a galvanometer mirror or a polygonal mirror which have been used for
the raster scanning of the stimulable phosphor sheet and the recording
medium in the conventional systems can be eliminated, whereby the scanning
systems can be simplified and compactly arranged. This contributes to
miniaturization of the system, and simplification of operation and
adjustment of the system. Further, the manufacturing cost of the system
can be lowered.
Further, since the stimulating light beam and the recording light beam is
controlled to correctly focus respectively on the stimulable phosphor
sheet and the recording medium on the basis of surface wobble of the
rotary plate measured by the focus measuring system independent from the
stimulating light beam projecting system and the recording light beam
projecting system, the stimulating light beam and the recording light beam
cannot be out of focus, whereby image information can be precisely read
out and recorded.
Further, the scanning for read-out by the stimulating light beam and the
scanning for recording by the recording light beam are effected by the use
of one and the same rotary plate. That is, the read-out system and the
recording system can have a single scanning system in common. This further
contributes to miniaturization of the system, simplification of operation
and adjustment of the system, and reduction of the manufacturing cost.
Further, in accordance with the first to third aspects of the present
invention, by mounting a plurality of stimulable phosphor sheets on the
rotary plate, read-out can be effected for a plurality of stimulable
phosphor sheets at one time, thereby improving the rate of image
information read-out.
Further, though the method of the present invention is particularly useful
for image read-out and reproduction using small size stimulable phosphor
sheets in which the rotary plates can be driven by a relatively small
driving force, the present invention can also be applied to image read-out
and reproduction using large size stimulable phosphor sheets.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view showing an apparatus for carrying out a
radiation image read-out and reproducing method in accordance with a first
embodiment of the present invention,
FIGS. 2A and 2B show examples of arrangement of the stimulable phosphor
sheet on the rotary plate,
FIG. 3 is a schematic view showing an apparatus for carrying out a
radiation image read-out and reproducing method in accordance with a
second embodiment of the present invention,
FIG. 4 is a schematic view showing an apparatus for carrying out a
radiation image read-out and reproducing method in accordance with a third
embodiment of the present invention, and
FIG. 5 is a schematic view showing an apparatus for carrying out a
radiation image read-out and reproducing method in accordance with a
fourth embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a schematic view showing a radiation image read-out apparatus a
and a radiation image recording apparatus b for carrying out a radiation
image read-out and reproducing method in accordance with a first
embodiment of the present invention. The radiation image read-out
apparatus a comprises a first rotary disk 2 on which one or more
stimulable phosphor sheets 1 are mounted and which is rotated in the
direction of arrow A and linearly moved in the direction of arrow B in
perpendicular to the rotational axis of the rotary disk 2; a light source
3, a condenser lens 4 and a half-silvered mirror 5 for projecting a laser
beam onto the stimulable phosphor sheet 1 mounted on the first rotary disk
2 as the stimulating light beam; and a photoelectric converter 6 which
receives light emitted by the stimulable phosphor sheet 1 upon stimulation
by the laser beam and converts it to an electric image signal. Between the
half-silvered mirror 5 and the photoelectric converter 6 is provided a cut
filter 7 which transmits only a predetermined wavelength range so that
only the light emitted by the stimulable phosphor sheet 1 can impinges
upon the photoelectric converter 6. The stimulable phosphor sheet 1 stores
a radiation image recorded thereon at a radiation image recording section
(not shown). In the radiation image exposure section, a radiation is
projected from a radiation source such as an X-ray tube toward an object,
and the stimulable phosphor sheet 1 is exposed to the radiation passing
through the object to have a radiation image of the object stored thereon.
The stimulable phosphor sheet 1 carrying a radiation image stored thereon
in such a manner is mounted on the first rotary disk 2 and the radiation
image is read out by the radiation image read-out apparatus a.
The radiation image recording apparatus b comprises a second rotary disk 12
on which one or more recording media 11 are mounted and which is rotated
in the direction of arrow C (the same direction as the direction of the
arrow A) in synchronization with the first rotary disk 2 and linearly
moved in the direction of arrow D in perpendicular to the rotational axis
of the rotary disk 12; a light source 13 and a condenser lens 14 for
projecting a laser beam modulated on the basis of an electric signal
output from the photoelectric converter 6 onto the recording medium 11
mounted on the second rotary disk 12 as the recording light beam. When an
internal modulation type semiconductor laser is employed as the light
source 13 for recording, the laser beam is output-modulated by an
oscillation output control electronic circuit which modulates the
oscillation output power. On the other hand, when a gas laser (e.g., He-Ne
laser) which is difficult of internal modulation is employed as the light
source 13 for recording, the recording light beam is modulated by an
external modulator such as an acoustooptic modulator (AOM), an
electrooptic modulator (EOM) or the like which modulates a laser beam
emitted from the laser. As the light source 13 for recording, an internal
modulation type light emission diode may also be employed. The light
source 3 for read-out need not be a laser but may be a light emission
diode or the like. Though the recording medium 11 may be a latent image
recording medium such as silver-salt photosensitive material, preferably,
the recording medium 11 is one of those which permit reproduction of the
radiation image as a visible image simultaneously with recording, e.g., a
heat-sensitive recording medium.
The first and second rotary disks 2 and 12 should be rotated in the same
phase, and it is preferred that the first and second rotary disks 2 and 12
are rotated so that the scanning speed is constant without depending upon
the light beam projecting position.
When reading out the image on the stimulable phosphor sheet 1, the
stimulable phosphor sheet 1 is mounted on the first rotary disk 2, and the
position of the condenser lens 4 and the half-silvered mirror 5 is
adjusted so that the laser beam (stimulating light beam) from the light
source 3 correctly focuses on the stimulable phosphor sheet 1. Then the
first rotary disk 2 is rotated at a constant linear velocity, and at the
same time, is moved in the direction of the line passing the center of
rotation of the first rotary disk 2 and the stimulating light beam
projecting position (the direction of the arrow B) at a speed determined
according to the distance of the stimulating light beam projecting
position from the center of rotation of the first rotary disk 2. This
causes the stimulating light beam to scan the stimulable phosphor sheet 1
along a spiral line at regular intervals, and by linearly moving the first
rotary disk 2 so that the stimulating light beam impinges upon the
stimulable phosphor sheet 1 from the outer peripheral side end to the
inner peripheral side end, the entire area of the stimulable phosphor
sheet surface can be scanned. Surface wobbling is apt to occur when the
first rotary disk 2 is rotated and when surface wobbling occurs, the
stimulating light beam cannot correctly focus on the stimulable phosphor
sheet 1. Accordingly, it is preferred that the surface wobble of the first
rotary disk 2 be measured by a separate optical system or the like, and
the position of the condenser lens 4 be controlled to compensate for the
surface wobble by a focus-servomechanism according to the measured surface
wobble of the first rotary disk 2.
The part of the stimulable phosphor sheet 1 exposed to the stimulating
light beam emits light in proportion to the stored radiation energy, and
the light impinges upon the light receiving portion of the photoelectric
converter 6 by way of the half-silvered mirror 5 and the cut filter 7.
Accordingly, the lights emitted from respective portions of the stimulable
phosphor sheet 1 exposed to the stimulating light beam successively enter
the photoelectric converter 6 as the stimulable phosphor sheet 1 scanned
by the stimulating light beam and are converted to electric image signals
by the photoelectric converter 6. The electric image signals thus obtained
are delivered to the radiation image recording apparatus b. As the
photoelectric converter 6, a photomultiplier or the like can be used.
Further, the photoelectric converter 6 may be provided with an amplifier
and/or an A/D converter, if necessary.
The rotational speed of the first rotary disk 2 in the direction of the
arrow A, that is, the rate of the main scanning by the stimulating light
beam, is determined taking into account the desired pitches of the picture
elements for reproduction of the radiation image as a visible image, the
rate of reading of the photoelectric converter 6, and the like. It is
preferred that the first rotary disk 2 be driven by a spindle motor and
the rotation of the disk 2 be stabilized by the use of a spindle servo.
Also the speed at which the first rotary disk 2 is moved in the direction
of the arrow B, that is, the rate of the sub-scanning, is determined
taking into account the desired pitches of the picture elements for
reproduction.
As described, one or more stimulable phosphor sheets 1 are mounted on the
first rotary disk 2. When a single stimulable phosphor sheet is mounted on
the first rotary disk 2, it is preferred that the stimulable phosphor
sheet 1a be symmetrical about the center of rotation of the first rotary
disk 2 as shown in FIG. 2A in order to stabilize rotation of the first
rotary disk 2. When a plurality of stimulable phosphor sheets 1b to 1e are
mounted on the first rotary disk 2 as shown in FIG. 2B, it is preferred
that the stimulable phosphor sheets 1b to 1e be positioned so that the
center of gravity of the stimulable phosphor sheets 1b to 1e coincides
with the center of rotation of the first rotary disk 2 in order to
stabilize rotation of the first rotary disk 2. When recesses or marks for
locating the stimulable phosphor sheets are provided on the disk 2,
positioning of the stimulable phosphor sheets is facilitated. Mounting and
demounting of the stimulable phosphor sheet can be facilitated by
providing the disk 2 and the stimulable phosphor sheet 2 with magnetic
means which attract each other.
The image information read out | | |
