JP2693719B2 - Radiation image eraser - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image erasing device for erasing a radiation image recorded on a stimulable phosphor. 2. Description of the Related Art So-called radiography using a silver salt to obtain a radiographic image has been conventionally used. However, in recent years, radiation images have been used without using a silver salt due to problems such as a decrease in silver resources. There is a need for a method of obtaining. Therefore, as an alternative to the conventional photographic method for obtaining a radiation image using silver salt, as shown in FIG. 3, the radiation (generally an X-ray) emitted from the radiation source S and transmitted through the object OBJ is converted into a plate shape. The stimulable phosphor (usually prepared by mixing the stimulable phosphor powder with a suitable binder and applying it to a base to finish it into a plate. Hereafter, this stimulable phosphor is simply referred to as a phosphor. (Note) It is made to absorb in SP, and after that, this fluorescent material for which radiation recording is carried out is excited with a certain energy, and the radiation energy accumulated by the fluorescent material is emitted as fluorescent light,
A method of obtaining a radiation image by detecting this fluorescence has been considered (see, for example, JP-A-55-12429). FIG. 4 is an explanatory view showing a structural example of a radiation image reading apparatus for reading a radiation image recorded on such a fluorescent body. In this figure, the laser beam emitted from the laser light source 1 is made to have a constant power by the light amount control unit 2, and after being focused in one direction by the cylindrical lens 3, the beam is expanded via the beam expander 4 and the mirror 5. The light enters the reflecting surface of the rotary polygon mirror 6 as an optical deflector. The rotary polygon mirror 6 rotates at a constant speed in the direction of the arrow in FIG. 1 in order to scan the laser beam in the main scanning direction X. The sub-scanning is performed by moving the fluorescent body SP in the Y direction. The laser beam deflected by the rotating polygon mirror 6 is
After passing through the f · θ lens 7 and being reflected by the mirror 8, the fluorescent substance S is passed through the cylindrical lens 9 arranged in the vicinity of the fluorescent substance SP.
Irradiate P. Therefore, fluorescent light is generated from the fluorescent body SP. This fluorescent light is incident on the end face (linear shape) of the light guide path 10 formed by a method of bundling optical fibers into a sheet shape, and then exits from the other end face (circular shape) of a photomultiplier tube or the like. It is incident on the first photodetector 11. The second photodetector 12 detects the laser beam at the scanning start end and obtains a synchronizing signal in the main scanning direction X of the reading scanning. Upon receiving this output, the controller 13 receives the timing signal. To the signal processing unit 14. Based on this timing signal, the signal processing unit 14 processes the output signal of the first photodetector 11 and reproduces the radiation image recorded in the fluorescent body SP. Incidentally, the cylindrical lens 3,
Reference numeral 9 corrects the tilt angle error of the reflecting surface of the rotary polygon mirror 6, and may be omitted when there is no problem in accuracy. By the way, when such a fluorescent body SP is strongly irradiated with light or heat, the radiation image is erased and it can be used again for photographing. 5 and 6 are schematic configuration diagrams of a conventional radiation image erasing device, respectively. FIG.
Shows an example of irradiating the fluorescent body SP, and FIG. 6 shows an example of irradiating the fluorescent body SP with the heater 16. In FIGS. 5 and 6, HL is a support. The heater 16 is not actively used because it may cause serious deterioration of the fluorescent body SP, and the light source 15 is generally used. However, in the conventional erasing apparatus using the light source 15, the output of the erasing apparatus fluctuates due to deterioration of the characteristics of the light source 15 due to its life or disconnection at worst. Even if it does, it is not possible to detect or confirm the abnormal state of these light sources 15, and the radiation image (hereinafter referred to as afterimage) of the fluorescent body SP after reading is not sufficiently erased. Or it may not be erased at all. This is because in order to erase the afterimage of the fluorescent body SP so that it can be used in a state where there is no problem in practical use, light irradiation of several million lux.sec or more is required, and it is erased in several tens of seconds. To do this, a light source 15 having a light intensity of several hundreds of thousands of lux or more must be used, and there is a risk that the eyeball may be damaged when the inside of the device is opened and viewed. If a photograph is taken again using a fluorescent substance SP in which such an afterimage is not erased sufficiently or not at all, the recorded image becomes double and the image quality is significantly impaired. It has to be redone, and wastes man-hours. In addition, the operator's psychological burden on whether or not the fluorescent body SP can be reused increases, which is not preferable. The present invention has been made in view of the above problems, and it is possible to reliably erase the radiation image (afterimage) accumulated and recorded in the stimulable phosphor even after reading. An object is to provide an image erasing device. The present invention, which solves the above-mentioned problems, provides a relative movement with respect to a stimulable phosphor on which a radiation image is stored and recorded.
Erasing means consisting of a plurality of erasing light sources for irradiating light while
And a value according to the output energy of the plurality of erasing light sources
Energy detecting means for detecting, to detect deterioration or breakage of the erasing light sources from the detected value of said energy detection means
Abnormality detecting means and the abnormality detecting means are inferior to the erasing light source.
When the depletion or disconnection is detected, the afterimage of the accumulative phosphor is erased.
The erasing means so as to secure the amount of exposure necessary to remove
And a control means for controlling . [0009] [action] on the basis of the detection result of the energy detection means, consumption
The deterioration or disconnection of the light source is detected by the abnormality detection means,
Based on the detection result of the abnormality detecting means , the erasing means was controlled so as to secure the exposure amount necessary for erasing the afterimage. Specifically, the time for irradiating the stimulable phosphor with optical energy and / or thermal energy was made variable based on the detection result of the energy detecting means. According to such a configuration, when the output energy of the energy generating means is large, the energy is irradiated for a short erasing time, and when the output energy is small, the energy is irradiated for a long erasing time, so that the accumulative fluorescence is obtained. The radiation image recorded on the body can be surely erased. Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.
It shows the state with the case removed. The same components as those in FIG. 5 are denoted by the same reference numerals. In the figure, a plurality of rod-shaped light sources 17 are arranged with their longitudinal direction oriented in a direction orthogonal to the moving direction of the fluorescent body SP, and the fluorescent body S
It is turned on when P is completely inserted into the case (not shown), and is turned off when erasing for a certain period of time is completed.
Note that the fluorescent body SP is gradually moved in the direction of the arrow in the figure during erasing to reduce unevenness in erasing due to variations in emission intensity among the light sources 17, but the fluorescent body SP is fixed. Alternatively, the light source 17 may be moved. Such a light source 1
A fluorescent lamp, a halogen lamp, a tungsten lamp or the like can be used as 7, and they may be of the same type.
A plurality of types may be mixed and used. A reflection member 18 for enhancing the erasing efficiency is provided above each light source 17, and the fluorescent body SP is deformed or discolored by the heat generated from the light source 17 between each light source 17 and the fluorescent body SP. An infrared cut filter 19 is provided to prevent this. And, a cooling fan 20 is provided on the side surface,
The photoelectric conversion element 21 such as a photodiode is movably movable along the arrangement direction of the light sources 17 so as to face the light sources 17.
Is provided. Although the filter 22 for reducing the amount of received light is provided on the light receiving surface of the photoelectric conversion element 21, it can be omitted if the photoelectric conversion element 21 can be arranged away from the light source 17. The photoelectric conversion element 21 moves in the direction of the arrow in the figure to detect the output level (output light intensity) of all the light sources (# 1 to # 5). FIG. 2 is a diagram showing the output of the photoelectric conversion element 21 (that is, the output level of each light source) at this time. Now, let us say that the output levels from the light sources 17 of # 1 to # 5 are L1 to L5, respectively. Here, whether or not the afterimage can be sufficiently erased is not determined only by the light output level from the light source 17. That is, as can be seen from [exposure amount (erase energy)] = [light intensity] × [light irradiation time], in order to completely erase the afterimage, an exposure amount of a predetermined amount or more should be secured. Must be
Therefore, in order to sufficiently erase the afterimage on the stimulable phosphor SP, it is necessary to consider not only the light output level from the light source 17 but also the erase time for irradiating the light at the level. The reference value in FIG. 2 corresponds to a light level capable of ensuring an exposure amount capable of completely erasing an afterimage when light irradiation is performed for a preset erasing time t. There is. That is, in FIG. 2, # 1,
With the output levels L1, L2, L4, and L5 from the light sources 17 of # 2, # 4, and # 5, it is possible to obtain an exposure amount that is sufficient to erase the afterimage in the erase time t. However, at the output level L3 of the light source 17 of # 3, sufficient afterimage erasing cannot be performed by erasing for the erasing time t. The broken line in the figure is the output of the light source of # 3 before it fluctuates due to deterioration or the like. The comparison between the reference value and the light output level is performed by the processing device 23. That is, the photoelectric conversion element 21
Is output to the processing device 23, and the output level at the position of each light source 17 is compared with the reference value. As a result of the comparison, if the output level is equal to or higher than the reference value, the afterimage can be sufficiently erased by irradiating during the erasing time t. On the other hand, when the output of the photoelectric conversion element 21 is equal to or less than the reference value, the time for erasing the erasing light (erasing time) is longer than the preset erasing time t according to the output of the photoelectric conversion element 21. Then, the exposure amount necessary to erase the afterimage is ensured. With this configuration, the afterimage is sufficiently erased, and therefore, when the stimulable phosphor SP is reused, the problem that the image becomes double and the image is remarkably damaged is solved. You can Further, when the output level of the light source 17 is equal to or lower than the reference value, the display device 24 may notify the operator that the output of the light source 17 is low. Note that a warning sound may be further emitted. As a result,
The operator can immediately recognize that the light source 17 is deteriorated. Although the five light sources are used in the above embodiment, the number of the light sources 17 is not limited to five.
There may be any number of light sources. Further, the light source 17 does not necessarily have to be provided in plural, and may be one if the functional deterioration is allowed to some extent. In actual use, there is a case where the light source 17 is broken and the output level of the photoelectric conversion element 21 is particularly low (for example, 0 level). In this case, the exposure amount control means 23 determines that the light source 17 has a disconnection, and the display device 2
You may make it display that on 4 and stop operation. With this configuration, the light emitting state of the light source can be automatically detected, and the image can be erased in an erasing time corresponding to the amount of exposure required to erase the image according to the detection result. By doing so, the afterimage recorded on the stimulable phosphor can be surely erased. In the above embodiment, one photoelectric conversion element is moved along the arrangement direction of the light sources, but a photoelectric conversion element may be provided for each light source. With such a configuration, the output level of each light source 17 can be measured at the same time, a moving mechanism for the photoelectric conversion element is not required, and the configuration can be simplified. The photoelectric conversion element 21 is not limited to the photodiode, and may be a phototransistor or an optical semiconductor such as CdS. When a light source that generates heat due to internal loss is used as the light source, a pyroelectric element, a thermocouple, or the like may be provided on the light source, the light source support, or the like to detect thermal energy. Further, the output energy of the light source can be substantially detected by detecting the current flowing through the light source. With this configuration, a sensor that directly detects energy is not required, and signal processing can be simplified. Further, when the characteristics of the fluorescent material SP are not deteriorated by heat, the heating energy irradiation type using an oven heating type may be used, and the state (level) of the output energy is detected by using a thermal sensor. can do. As described above in detail, according to the present invention, the value according to the output energy of the energy generating means
Based on the detection result of the energy detection means for detecting
Deterioration or disconnection of the erasing light source is detected by the abnormality detection means,
The radiation image recorded on the accumulative phosphor can be surely erased by ensuring the exposure amount necessary for erasing the radiation image based on the detection result of the abnormality detecting means. An image erasing device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing an output level of each light source. FIG. 3 is a diagram showing recording of a radiation image on a phosphor. FIG. 4 is a diagram showing a configuration example of a radiation image reading device for reading a radiation image recorded on a fluorescent body. FIG. 5 is a configuration diagram of a conventional radiation image erasing device. FIG. 6 is another configuration diagram of a conventional radiation image erasing device. [Description of Reference Signs] 17 Light Source 18 Reflecting Member 19 Infrared Cut Filter 20 Cooling Fan 21 Photoelectric Conversion Element 22 Dimming Filter 23 Processing Device 24 Display Device SP Accumulative Fluorescent Body HL Support

Continuation of front page    (56) References JP-A-59-202099 (JP, A)                 JP 59-72079 (JP, A)                 JP 58-80633 (JP, A)                 JP-A-57-182992 (JP, A)                 JP-A-55-97612 (JP, A)                 JP-A-53-20092 (JP, A)

Claims (1)

(57) [Claims] For stimulable phosphors on which radiographic images are stored and recorded,
Consists of multiple erasing light sources that emit light while moving relative to each other
Detecting means and a value corresponding to the output energy of the plurality of erasing light sources are detected
Energy detecting means for, of the erasing light sources from the detected value of said energy detection means
Abnormality detecting means for detecting deterioration or disconnection, and the abnormality detecting means for detecting deterioration or disconnection of the erasing light source
Exposure, the exposure required to erase the afterimage of the accumulative phosphor.
Control means for controlling the erasing means so as to secure the amount of light
When the radiation image erasing apparatus characterized by having a. 2. The abnormality detecting unit detects deterioration or disconnection of the erasing light source.
Upon detection, the control means forwards the output energy.
In order to increase the time to irradiate the storage phosphor,
The radiation image erasing device according to claim 1, wherein the removing means is controlled . 3. The abnormality detecting unit detects deterioration or disconnection of the erasing light source.
Upon detection, the control means controls the output light intensity of the erasing light source.
Radiographic image erasing apparatus according to claim 1, wherein the controller controls the erasing means to increase the degree.