Read-out device for radiation image storage panel

A read-out device for a radiation image storage panel comprising a read-out means for photoelectrically reading out radiation image information recorded and stored in the panel containing a stimulable phosphor, a panel-conveying means for conveying the panel to the read-out means and a panel-receiving means for receiving the panel from the outside and conveying it to the panel-conveying means in a housing is disclosed. The read-out device is provided with a detecting means for detecting extraneous materials deposited on the surface of the panel to be fed to the panel-receiving means.

BACKGROUND OF THE INVENTION 
1. Field of the invention 
The present invention relates to a read-out device for use in performing a 
radiation image recording and reproducing method employing a radiation 
image storage panel having a stimulable phosphor. 
2. Description of prior art 
As a method for obtaining a radiation image, there has been conventionally 
employed a radiography utilizing a combination of a radiographic film 
having a sensitive silver salt material layer and an intensifying screen. 
As a method replacing the above-mentioned conventional radiography, a 
radiation image recording and reproducing method employing a stimulable 
phosphor as described, for instance, in Japanese Patent Provisional 
Publication No. 55(1980)-12145, has been developed and paid much 
attention. In this method, a radiation image storage panel (a stimulable 
phosphor sheet) having a stimulable phosphor is used and this method 
involves steps of causing the stimulable phosphor in the panel to absorb a 
radiation having passed through an object or having radiated from an 
object; exciting (or scanning) the phosphor with an electromagnetic wave 
such as visible light or infrared rays (i.e., stimulating rays) in time 
sequence to release radiation energy stored in the phosphor as light 
emission (i.e., stimulated emission); photoelectrically reading out the 
emitted light to obtain electric signals; and visualizing the electric 
signals as an image. 
The radiation image storage panel used in the radiation image recording and 
reproducing method is sometimes called a stimulable phosphor sheet. 
Generally, the stimulable phosphor sheet comprises a support and a 
phosphor layer provided on one side thereof and is in the form of a sheet 
of rectangle, square, etc. (one side having a length of about 20 to 50 
cm). Generally, a transparent protective film made of a plastic film is 
provided on the surface of the phosphor layer to protect the phosphor 
layer from chemical denaturation or physical shock. 
The phosphor layer comprises a stimulable phosphor and a binder for 
retaining the phosphor in a dispersed form. The stimulable phosphor has 
such a property that when it is irradiated with a radiation such as 
X-rays, it is caused to absorb the radiation and then it emits light 
(stimulated emission) when excited with an electromagnetic wave such as 
visible light or infrared rays (i.e., stimulating rays). Thus, a radiation 
having passed through an object or having radiated from an object is 
absorbed by the phosphor layer of the panel in proportion to the amount of 
the radiation and a radiation image (radiation image information) of the 
object is formed as a radiation energy-stored image on the panel. When the 
panel is excited with an electromagnetic wave in time sequence, the 
radiation energy-stored image is released as stimulated emission. The 
stimulated emission is photoelectrically detected to obtain electric 
signals to reproduce the radiation energy-stored image of the object as a 
visible image. 
In the radiation image recording and reproducing method, a radiation image 
is obtainable with a sufficient amount of information by applying a 
radiation to the object at a relatively small dose as compared with the 
conventional radiography. Accordingly, the radiation image recording and 
reproducing method is of great value, especially when the method is used 
for medical diagnosis by a radiography with X-rays. 
Further, it has been found that the method can be advantageously used for 
the case where autoradiography is carried out in isolating and identifying 
high-molecular weight materials such as protein, nucleic acid, etc. 
originating from organisms and evaluating their characteristics. 
In carrying out the radiation image recording and reproducing method 
employing the radiation image storage panel, there is conventionally used 
a system wherein a recording means for recording a radiation image on the 
panel, a read-out means for photoelectrically reading out the radiation 
image and an erasure means for erasing the remaining radiation image on 
the panel after read-out operation are separately provided or a device 
wherein the recording means, the read-out means and the erasure means are 
provided in a combination. Particularly, when the radiation image 
recording and reproducing method is performed by using a system wherein 
the recording means and the read-out means are separately provided, each 
panel is placed in a cassette (a light-shielding case) to prevent 
information on an image recorded and stored in the panel from being lost 
by exposure and lowering in the quality of a reproduced image from being 
caused thereby. The recording of the radiation image is made on the panel 
as placed in the cassette and the cassette is then fixed to the read-out 
means where the panel is taken out of the cassette and the read-out 
operation for the radiation image stored in the panel is conducted. 
Generally, the removal of the panel from the cassette is done by a 
cassette-removing means comprising a sucker provided within the system. 
When the panel having the radiation image recorded and stored therein is 
exposed by allowing it to stand in a light room, the degree of loss of the 
radiation image is relatively low, when the exposure time is very short. 
However, when the panel is used for medical diagnosis, radiation image 
information is information on the human body (X-ray photograph of a region 
of the human body) and hence the image must be obtained with high 
accuracy. 
In the radiation image information obtained by utilizing autoradiography, 
the image information is to be locational information (image information 
being recognized by a pattern) on the electrophoretically resolved pattern 
of radioactively labeled nucleic acid-cleavage products. Thus, not so much 
high resolution and accuracy are required for the image, as compared with 
the case for medical use. Therefore, it is not always necessary that the 
panel as placed in the cassette is fixed to the read-out means. It may be 
contemplated that the panel which is not placed in the cassette is fixed 
to the read-out means. In the case where the panel is not placed in any 
cassette, the means for taking the panel out of the cassette can be 
omitted, the system can be made compact and the manufacturing cost of the 
read-out means can be reduced. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a read-out device for a 
radiation image storage panel, which is provided with an auxiliary member 
for preventing a radiation image storage panel having extraneous materials 
deposited thereon from being introduced into the read-out means, when the 
panel which has radiation image information recorded and stored therein 
and is not placed in any cassette is introduced into the read-out means. 
The present invention provides a read-out device for a radiation image 
storage panel, wherein a read-out means for photoelectrically reading out 
radiation image information recorded and stored in a radiation image 
storage panel containing a stimulable phosphor, a panel-conveying means 
for conveying the panel to the read-out means and a panel-receiving means 
for receiving the panel from the outside and conveying it to the 
panel-conveying means are placed in a housing, characterized in that there 
is provided a detecting means for detecting extraneous materials deposited 
on the surface of the panel to be fed to the panel-receiving means. 
When the read-out device provided with a panel-feeding means according to 
the present invention is used, any extraneous materials can be detected 
and the radiation image storage panel having extraneous materials 
deposited thereon can be prevented from being introduced into the read-out 
device, when extraneous materials such as pieces of paper, electrophoretic 
membrane, resin sheets, etc. are deposited on the surface of the panel in 
introducing the panel having radiation image information recorded and 
stored therein, which is not placed in any cassette, into the read-out 
device. 
Particularly, when the panel is employed in a system using radioisotope, 
for example, in recording an autoradiograph of an electrophoretically 
resolved pattern of the radioactively labeled cleavage products of a 
nucleic acid, there is a possibility that the panel on the surface of 
which pieces of paper, electrophoretic membrane and resin sheet containing 
radioisotope are deposited is fed to the read-out device. In such a case, 
the extraneous materials containing radioisotope can be detected by the 
extraneous material-detecting means of the present invention so that such 
extraneous materials can be prevented from being introduced into the 
read-out device, whereby the inside of the read-out device can be 
effectively prevented from being contaminated by a radiation. 
The extraneous material-detecting means may be electrically connected to 
the panel feeding means and a signal for stopping the feed of the panel 
may be given to the panel-feeding means, when the extraneous materials are 
detected by the detecting means. In this way, the extraneous materials 
(undesired deposits) can be prevented easily and reliably from being 
introduced into the read-out device.

DETAILED DESCRIPTION OF THE INVENTION 
The read-out device for the radiation image storage panel accoding to the 
present invention will be described in more detail below by referring to 
the accompanying drawings. 
FIG. 1 is a schematic view illustrating the internal structure of the 
read-out device for the radiation image storage panel according to the 
present invention The function of the read-out section of the read-out 
device is known. Accordingly, the device will be briefly illustrated below 
to facilitate the understanding of the read-out device for the radiation 
image storage panel. 
Referring to FIG. 1, the read-out device 10 is provided with a read-out 
means R for photoelectrically reading out radiation image information 
recorded and stored in the panel and a conveying means A for conveying the 
panel to the read-out means R. The read-out means R and the conveying 
means A are placed in a housing 11. Before the conveying means A, a 
panel-receiving means E for receiving the panel from the outside and 
conveying it to the panel-conveying means is provided at the upper part of 
the housing 11. There is provided a panel-feeding means S which adjoins 
the panel-receiving means E and is provided with an extraneous 
matter-detecting means D according to the present invention. 
The radiation image storage panel P having radiation image information 
recorded thereon is fed to the read-out means through a panel-feeding part 
12 provided at the upper part 13 of the housing 11. The panel P is 
introduced into the device while it is held between an inner driver roller 
111 (which is an element of the panel-receiving means E) and an outer 
conveyor belt (endless conveyor belt) 112 for conveying the panel forward. 
The panel is then transferred to a guide member 113 which is approximately 
vertically provided. 
The panel-receiving means E include a mechanism which conveys the panel 
while the panel P is bent to allow its traveling direction to be turned. 
This mechanism comprises an outer endless conveyor belt 112 (it is 
desirable that the panel is driven by this belt) supported by two rollers 
112a and 112b positioned outside the housing and an inner roller 111 
positioned inside the housing and interlocked with the conveyor belt 112. 
An inner endless conveyor belt may be used in place of the roller 111. 
However, it is desirable that the rotation of the roller 111 or the inner 
endless conveyor belt is made by a driven rotation which is caused by the 
movement of the outer endless conveyor belt in contact therewith through 
the panel P under pressure. 
It is desirable that the revolution of the outer endless conveyor belt 112 
is made on the axis of the roller 112a (or 112b) as a rotating shaft, is 
released from the opposing roller (or the inner endless conveyor belt) at 
the side of other roller 112b and opened outward to thereby release the 
interlocking. When such a structure is used, there is an advantage that 
the panel P is easily taken out, when the panel P is stopped or stays on 
the side of the panel-receiving means E. 
The panel P is passed through the guide member 113 and then fed to a 
conveyor belt 114 arranged in a roughly right-angled form and provided at 
the lower corner of the device. 
The panel is then transferred to a conveyor belt 115 which is positioned at 
the bottom of the device, arranged by starting from the end part of the 
belt 114 and is horizontally provided. Above the belt 115 is provided the 
read-out means R. The read-out means R is provided with a laser source 
116. On the laser beam-guiding-out side of the laser source 116, there are 
provided a mirror 116b which reflects laser beam 116a to turn its 
direction, a galvanometer mirror 116c which reflects and deflects laser 
beam 116a to irradiate the panel with the laser beam (i.e., to carry out 
main scanning) and a condensing reflection mirror 116d for efficiently 
condensing stimulated emission emitted from the panel. Further, there is 
provided a condensing optical element 116e for condensing stimulated 
emission emitted from the panel against the condensing mirror 116d and 
along main scanning line at the scanning position of the laser beam 116a 
on the panel. At the top of the condensing optical element 116e is 
provided a photomultiplier 116f as a photoelectrical read-out means. 
In the read-out means R, a radiation image (radiation image information) 
recorded on the panel P is read out. Namely, laser beam 116a is emitted 
from the laser source 116 and at the same time, the galvanometer mirror 
116c is shaken whereby main scanning on the panel having a radiation image 
stored therein with laser beam 116a can be made. At the same time, the 
panel P is conveyed by a conveyor belt 115 so that it is moved forward. 
Thus, sub-scanning is made, whereby two-dimensional scanning can be 
conducted. Stimulated emission emitted from the panel by scanning the 
panel with laser beam 116a is reflected directly or by the condensing 
reflection mirror 116a, enters through the incident edge of the condensing 
optical element 116e into the element 116e, is guided under total 
reflection, reaches the photomultiplier 116f and is received thereby to 
photoelectrically read out the stimulated emission. 
Image signals which have been photoelectrically read out are reproduced as 
a visible image on a display device such as CRT. 
After the read-out operation has been completed, the panel P is passed 
through a conveyor belt 117 and pairs of rollers 118 and is discharged to 
a tray 119 which is provided in a panel discharge part 14 positioned on 
the side of the device. 
The detecting means for detecting extraneous materials deposited on the 
surface of the radiation image storage panel according to the present 
invention will be described in more detail below by referring to FIGS. 2 
to 5. 
Usually, the detecting means for detecting undesired deposits on the 
surface of the panel is provided just before the panel-receiving means. 
The detecting means may be separately provided as an independent device 
However, it is desirable that the panel-feeding means for feeding the 
panel to the panel-receiving means is provided with the detecting means. 
It is desirable that the panel-feeding means is such a device that driving 
force for feeding the panel is substantially given only by a roller or an 
endless belt in contact with one side of the panel under rotation. 
The radiation image sotrage panel comprises a support and a stimulable 
phosphor layer provided on one side of the support as described above. 
Hence, the panel is flexible, but considerably rigid. Therefore, when the 
panel received by the panel receiving means E is bent during the course of 
movement while putting it between a driving belt and a driven roller (or a 
driven belt; the same applies hereinbelow) under pressure, the panel 
resists the movement and the panel is often stopped or stays. 
Particularly, when the angle of bend is a right angle or so, the panel 
highly resists bending pressure. 
Accordingly, when the panel is forced to be introduced into the 
panel-receiving means E or its feed rate is too slow, a difference between 
the feed rate of the panel and the conveying speed in the panel-receiving 
means E becomes greater and the panel is liable to be stopped in the 
panel-receiving means. When the panel is manually fed to the panel 
receiving means, there is a problem that troubles are liable to be caused 
in the panel-receiving means. 
FIG. 2 is an enlarged view of a section showing the panel-feeding means S, 
the extraneous material-detecting means D and the panel-receiving means E 
of FIG. 1. FIG. 3 is a plan view showing the panel-driving part of the 
panel-feeding means S of FIG. 2. 
There is shown an embodiment in which the panel-feeding means S comprises a 
panel-driving part 22 provided with a panel-driving roller 21 fixed to the 
upper part 13 of the housing and a lid part 24 provided with a driven 
roller 23 positioned opposite the panel-driving roller 21 and the lid part 
24 is fixed to the panel-driving part in such a manner that it can be 
opened and closed. The panel-driving roller 21 may be composed of one 
roller, but it is desirable that it is composed of a plurality of rollers 
which function as a single roller as a whole, as shown in FIG. 3. The 
panel-driving roller may be connected directly to a driving source. 
Alternatively, it may be connected to any roller on the side of the 
panel-receiving means to obtain rotating energy from the panel receiving 
means, that is, to obtain driving energy for moving the panel forward. 
Usually, the panel P is introduced into the panel-receiving means in such a 
manner that the phosphor layer side is positioned downward to facilitate 
the read-out operation in the read-out device and to prevent undesired 
exposure. Thus, it is desirable that the panel-feeding means is provided 
in such a manner that the panel contact driving part of the panel forward 
driving part thereof is positioned upward. 
It is also desirable that the rotation of the driving roller 21 of the 
panel-feeding means S is synchronized with that of the driving roller 111 
of the panel-receiving means E through a chain 25 so as to allow a 
panel-feeding speed from the panel-feeding means S to agree with a 
panel-receiving speed in the panel-receiving means E. In this way, the 
panel can be smoothly fed to the panel-receiving means E from the 
panel-feeding means S and the panel can be prevented from being damaged or 
the surface of the panel can be prevented from being marred. 
Each of the panel-driving roller and the driven roller may be replaced by 
an endless belt. The driven roller (endless belt) for assisting the 
function of the panel-driving roller or endless belt may be optionally 
provided. 
The panel-driving part is provided with one or more through-holes 27 so 
that a detection system (usually, a detection system utilizing light 
reflection being used) from the extraneous material-detecting means D is 
brought into contact with the surface of the panel through light. 
FIGS. 4 and 5 are views illustrating embodiments of the constitution of the 
extraneous material-detecting means D. 
FIG. 4 is a partial cross-sectional view illustrating the relationship of 
the panel-feeding means S, the extraneous material-detecting means D and 
the panel P taken along the line I--I in FIG. 3. 
FIG. 4 shows a typical embodiment of the extraneous material-detecting 
means comprising a light-emitting part 41 and a light-receiving part 42. 
The surface of the radiation image storage panel is irradiated with light 
(an arrow) emitted from a light-emitting part 41 and the reflected light 
(an arrow) is detected by the light-receiving part 42 to detect light 
reflectance on the surface of the panel. Fluctuation in the reflectance 
between the panel surface and the surface of an extraneous material (e.g., 
pieces of paper, electrophoretic membrane or resin sheet) is caused, 
whereby the existence of the extraneous materials can be detected. 
As light used in the case where the above-described light detection system 
is used, it is preferred to use infrared rays having a wavelength of not 
less than 800 nm (e.g., infrared rays having a wavelength of about 950 nm) 
emitted by using a semiconductor emission device as a light source. The 
stimulable phosphor contained in the radiation image storage panel is 
hardly sensitive to infrared rays within the wave range described above. 
Thus, when infrared rays are used as detecting light, the extraneous 
materials can be detected without giving an adverse effect to the 
radiation image recorded on the panel. 
In the present invention, the extraneous material-detecting means are 
usually arranged in the form of a combination of a plurality of detectors 
in a row. Usually, a plurality of the detecting means (three detecting 
means in the embodiment shown in FIG. 3) are arranged in a row such that 
they are positioned in parallel with the panel surface and in the 
direction perpendicular to the traveling direction of the panel. If 
desired, a plurality of the rows of the detecting means may be arranged 
along the traveling direction of the panel. In this case, it is desirable 
that neighboring detecting means in the neighboring rows are arranged 
alternately (in a zigzag form) so that the detecting zones of the 
detecting means in the neighboring rows are not overlapped. 
Further, it is desirable that the detecting means are provided at a 
position or in the vicinity of a position where the panel is hardly moved 
up and down. 
FIG. 5 shows an embodiment wherein there are provided a plurality of 
detecting means D.sub.1 and D.sub.2 which emit a detecting light having 
different wavelengths from each other (FIG. 5 shows the case where two 
detecting means are provided. 
The detecting means of FIG. 5 comprises at least two detecting means 
D.sub.1 and d.sub.2, each of the devices D.sub.1 and D.sub.2 having a 
light-emitting part and light-receiving part as shown in FIG. 4. The 
surface of the radiation image storage panel is irradiated with light 
emitted from each light-emitting part and each of the reflected light is 
detected by the light-receiving part to detect light reflectance on the 
surface of the panel P. Variation (or difference) of the reflectance 
between the panel surface and the surface of an extraneous material is 
caused, whereby the existence of the extraneous materials can be detected. 
In the detecting system of FIG. 5, light emitted from the light-emitting 
part of the device D.sub.1, must have a different wavelength from that of 
light emitted from the light-emitting part of the device D.sub.2. 
The number of the kinds of the extraneous materials and the state thereof 
vary depending on the cases where the panel is used. For example, various 
kinds of the extraneous materials such as paper, electrophoretic membranes 
and resin sheets are sometimes deposited on the surface of the panel, or 
even when only one kind of the extraneous material is deposited, there is 
a possibility that it is deposited thereon in different states (e.g., in a 
dry state and in a wet state). In these cases, there often arises 
difficulty in detecting the extraneous material or materials, when only 
one kind of light having a wavelength is used. For this reason, it is 
desirable that there are used at least two light-emitting parts wherein 
light emitted from one light-emitting part has a different wavelength from 
that of light emitted from the other light-emitting part, while taking the 
number of the kinds of the extraneous materials into consideration. For 
example, there are used two semiconductor emission devices wherein one 
light emitting part emits light having a wavelength of 600 nm (red) and 
the other emits light having a wavelength of 500 nm (orange). However, 
when light emitted has a wavelength of not more than 800 nm, it is 
desirable that the amount of light is kept at a low level so as not to 
cause the deterioration of the radiation image recorded on the panel. 
In the above embodiment, the extraneous material-detecting means is fixed 
to the housing. The extraneous material-detecting means may be separately 
provided and when necessary, it may be fixed to the housing. 
While there has been described the read-out means provided with only the 
read-out means as a functioning means, the read-out means for the 
radiation image storage panel according to the present invention may be 
optionally provided with other means such as an erasure means for 
releasing and erasing radiation image which is left in the panel even 
after the completion of the read-out operation.