Radiant energy – Source with recording detector – Using a stimulable phosphor
Reexamination Certificate
2000-04-25
2002-09-24
Dang, Hung Xuan (Department: 2873)
Radiant energy
Source with recording detector
Using a stimulable phosphor
C250S584000
Reexamination Certificate
active
06455868
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a radiation image read-out method, wherein light emitted from a front surface of a radiation image storage panel, which is provided with a stimulable phosphor layer, and light emitted from a back surface of the radiation image storage panel are detected respectively.
2. Description of the Prior Art
It has been proposed to use stimulable phosphors in radiation image recording and reproducing systems. Specifically, a radiation image of an object, such as a human body, is recorded on a sheet provided with a layer of the stimulable phosphor (hereinafter referred to as a stimulable phosphor sheet). The stimulable phosphor sheet, on which the radiation image has been stored, is then exposed to stimulating rays, such as a laser beam, which cause it to emit light in proportion to the amount of energy stored thereon during its exposure to the radiation. The light emitted by the stimulable phosphor sheet, upon stimulation thereof, is photoelectrically detected and converted into an electric image signal. The image signal is then processed and used for the reproduction of the radiation image of the object as a visible image on a recording material.
As one of technique for photoelectrically detecting the light emitted by a stimulable phosphor sheet, a technique for detecting light emitted from front and back surfaces of a stimulable phosphor sheet and thereby detecting two image signals from the opposite surfaces of the stimulable phosphor sheet has heretofore been known. With the technique for detecting light emitted from front and back surfaces of a stimulable phosphor sheet and thereby detecting two image signals from the opposite surfaces of the stimulable phosphor sheet, for example, a radiation image storage panel is employed, which comprises a transparent substrate (such as transparent film having a thickness falling within the range of 100 &mgr;m to 500 &mgr;m) and a stimulable phosphor layer overlaid on the front surface side of the transparent substrate. Radiation is irradiated to the radiation image storage panel from its stimulable phosphor layer side, and radiation image information is stored on the stimulable phosphor layer of the radiation image storage panel. Thereafter, irradiation of stimulating rays is performed from the stimulable phosphor layer side of the radiation image storage panel. When the radiation image storage panel is exposed to the stimulating rays, light is emitted from each of the front surface side (i.e., the stimulable phosphor layer side) of the radiation image storage panel and the back surface side (i.e., the transparent substrate side) of the radiation image storage panel. The light emitted from the front surface side of the radiation image storage panel and the light emitted from the back surface side of the radiation image storage panel are respectively detected with photoelectric read-out means, which is located on the front surface side of the radiation image storage panel, and photoelectric read-out means, which is located on the back surface side of the radiation image storage panel. The technique for detecting light emitted from front and back surfaces of a stimulable phosphor sheet and thereby detecting two image signals from the opposite surfaces of the stimulable phosphor sheet is disclosed in, for example, U.S. Pat. No. 4,346,295. In cases where the technique for detecting light emitted from front and back surfaces of a stimulable phosphor sheet and thereby detecting two image signals from the opposite surfaces of the stimulable phosphor sheet is utilized, an addition process can be performed on the image signal components of the two image signals having been detected from the opposite surfaces of the stimulable phosphor sheet, which image signal components represent corresponding pixels on the front and back surfaces of the stimulable phosphor sheet. In this manner, the light collecting efficiency can be enhanced. Further, since noise components are uniformized, the signal-to-noise ratio of the obtained radiation image can be enhanced.
Ordinarily, the conventional radiation image storage panels are provided with thin film as the substrate and are flexible as a whole. Also, in cases where an image read-out operation is performed on the radiation image storage panel, for example, the stimulating rays are deflected in a main scanning direction, and the radiation image storage panel is conveyed in a sub-scanning direction. In this manner, the radiation image storage panel is scanned with the stimulating rays in two-dimensional directions. In cases where a technique for detecting light emitted from one surface alone of a radiation image storage panel (i.e., from only the front surface side of the radiation image storage panel) and thereby detecting only one image signal from the one surface of the radiation image storage panel is employed, no limitation is imposed upon how the back surface of the radiation image storage panel is to be supported. Therefore, in such cases, the back surface of the radiation image storage panel can be supported appropriately and conveyed at the read-out position that is scanned with the stimulating rays. Accordingly, even if the radiation image storage panel has flexibility as described above, the radiation image storage panel can be kept in a stable state at the read-out position by being supported appropriately from the back surface side of the radiation image storage panel at the read-out position. As a result, the image read-out operation can be performed accurately, while the radiation image storage panel is being kept in the state free from any deformation, sway, or the like.
However, it has been found that, in cases where the conventional radiation image storage panel having the flexibility as described above is employed in the technique for detecting light emitted from front and back surfaces of a radiation image storage panel and thereby detecting two image signals from the opposite surfaces of the radiation image storage panel, the problems described below occur. Specifically, in cases where the radiation image storage panel having the flexibility is employed, in order for the image read-out operation to be performed accurately, a conveyance mechanism cannot be kept simple.
More specifically, in cases where the technique for detecting light emitted from front and back surfaces of a radiation image storage panel and thereby detecting two image signals from the opposite surfaces of the radiation image storage panel is employed, it is necessary that a light guide member, or the like, for detecting the light emitted by the radiation image storage panel is located on the back surface side of the radiation image storage panel and at a position close to it at the read-out position. Therefore, the ordinary member for supporting the radiation image storage panel cannot be located on the back surface side of the radiation image storage panel at the read-out position. Accordingly, if the radiation image storage panel having the flexibility is employed in such cases, a complicated mechanism for preventing the radiation image storage panel from being deformed due to deflection by gravity must be utilized at the read-out position.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a radiation image read-out method, wherein an operation for detecting light emitted from front and back surfaces of a radiation image storage panel and thereby detecting two image signals from the opposite surfaces of the radiation image storage panel is capable of being performed accurately.
Another object of the present invention is to provide a radiation image read-out method, wherein an operation for detecting light emitted from front and back surfaces of a radiation image storage panel and thereby detecting two image signals from the opposite surfaces of the radiation image storage panel is capable of being performed accurately and efficiently.
The present invention provides a radiation image read-out method, wherein a radia
Dang Hung Xuan
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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