Radiant energy – Source with recording detector – Using a stimulable phosphor
Reexamination Certificate
2001-11-08
2004-11-09
Gagliardi, Albert (Department: 2878)
Radiant energy
Source with recording detector
Using a stimulable phosphor
Reexamination Certificate
active
06815703
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cassette for storing a stimulable phosphor sheet and used for photographing a radiation image. More specifically, the present invention relates to a cassette comprising means for erasing radiation energy remaining in a stimulable phosphor sheet stored therein.
The present invention also relates to a radiation image photographing apparatus for photographing (recording) a radiation image in the stimulable phosphor sheet stored in the cassette.
Furthermore, the present invention relates to a photographing information registration apparatus for registering photographing information regarding the stimulable phosphor sheet stored in the cassette.
Moreover, the present invention also relates to a radiation image information reading apparatus for reading radiation image information recorded in the stimulable phosphor sheet stored in the cassette.
2. Description of the Related Art
There has been known stimulable phosphor storing a portion of energy of radiation irradiated thereon and emitting phosphorescent light in accordance with the stored radiation energy upon exposure to an excitation light such as visible light and a laser beam. Consequently, radiation image recording/reproducing systems using stimulable phosphor sheets having the stimulable phosphor on substrates thereof have been in wide use.
A radiation image recording reproducing system records radiation image information of a subject such as a human body in a stimulable phosphor sheet by irradiating radiation that has passed through the subject on the sheet. Thereafter, the stimulable phosphor sheet is scanned two-dimensionally with an excitation light such as a laser beam to cause the sheet to emit phosphorescent light from an area where the excitation light is irradiated, and the phosphorescent light is read by photoelectric reading means. In this manner, an image signal representing the radiation image information is obtained by the radiation image recording/reproducing system (see Japanese Unexamined Patent Publication Nos. 55(1980)-12429, 55(1980)-116340, and 56(1981)-104645, for example).
The image signal obtained by the system in the above manner is subjected to image processing such as tone processing and frequency processing appropriate for observing a radiation image represented by the image signal, and the image is reproduced as a visible image on a film or displayed on a CRT display device for diagnosis.
The stimulable phosphor sheet can be used repeatedly for recording radiation image information again if an erasing light for releasing radiation energy remaining in the sheet is irradiated on the sheet after reading. However, even if the erasing process described above is carried out after reading, radiation energy is often stored in the sheet by being exposed to natural radiation before the sheet is used for recording radiation image information again. Therefore, even in the case where the stimulable phosphor sheet has already been subjected to the erasing process (primary erasing process), the erasing process is generally carried out again (secondary erasing process) immediately before the stimulable phosphor sheet is reused for recording radiation image information.
As has been described in U.S. Pat. No. 4,849,630 for example, the stimulable phosphor sheet is often stored in a light-shielding cassette. The cassette stores only one sheet and usually comprises a casing box having an opening for inserting or taking out the sheet and a lid for opening or closing the opening.
When a radiation image is photographed (recorded) by using such a cassette, the cassette is placed in a position where radiation that has passed through a subject is irradiated, for example. In this manner, the radiation is irradiated on the stimulable phosphor sheet stored in the cassette, and the radiation image is recorded in the sheet.
The cassette after photographing the radiation image is set in a radiation image information reading apparatus, as has been described in U.S. Pat. No. 5,308,994, for example. The stimulable phosphor sheet is taken out from the cassette and subjected to radiation image information reading processing.
Meanwhile, for the stimulable phosphor sheet that has the radiation image recorded therein, information such as a name and a body portion of the subject and a radiation dosage needs to be specified for the subsequent radiation image information reading and sheet management. In many cases, subject information such as the name and gender of the subject and ID (identification) information including photographing information such as the date of photographing and the photographed body portion is registered with a photographing information registration apparatus. The photographing information registration apparatus is placed together with or connected to the radiation image photographing apparatus. The photographing information registration apparatus is connected to the radiation image information reading apparatus in some cases so that a radiation image information reading condition can be determined based on the photographing information.
In the case where the stimulable phosphor sheet is stored in the cassette, the subject information and the photographing information is often represented by a bar code and the bar code is pasted to the cassette.
Meanwhile, the time necessary for the erasing process such as the primary erasing and the secondary erasing is substantially long compared to the time necessary for the radiation image information reading process. This fact has been hampering the processing ability of the radiation image recording/reproducing system using a stimulable phosphor sheet. In consideration of such a situation, a cassette comprising an emitter for the erasing process has been proposed as in U.S. Pat. No. 4,849,630, aiming at an improvement of the erasing process.
Although the cassette having the emitter can achieve a predetermined object, the cassette needs to be brought to a power supply unit for supplying an electric current to the emitter. Furthermore, appropriate control of emission time of the emitter is difficult. With regard to these points, there remained room for improvement.
SUMMARY OF THE INVENTION
The present invention has been conceived based on consideration of the above circumstances. An object of the present invention is therefore to obviate the conveyance of a cassette having an erasing ray emitter to a power supply, and to appropriately control an emission time of the emitter.
Another object of the present invention is to provide a radiation image photographing apparatus, a photographing information registration apparatus, and a radiation image information reading apparatus enabling appropriate control of the emission time of the emitter from outside of the cassette.
Still another object of the present invention is to provide a radiation image photographing apparatus and a photographing information registration apparatus not hampering photographing of a radiation image even if the emission time is controlled.
A cassette of the present invention is a cassette for storing a stimulable phosphor sheet having a stimulable phosphor layer formed on a sheet-like substrate and used for recording a radiation image therein, and the cassette comprises:
an emitter for emitting an erasing light to the sheet stored in the cassette;
a power supply for causing the emitter to emit the erasing light; and
a control circuit for controlling a time of emission from the emitter powered by the power supply.
The control circuit controls the emission time based on control information input from outside of the circuit.
More specifically, a circuit for controlling the emission time based on control information output from an apparatus for photographing the radiation image on the stimulable phosphor sheet may be used as the control circuit. Alternatively, a circuit for controlling the emission time based on control information output from an apparatus for registering photographing information regarding the stimulable phos
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