PATENT ABSTRACT
A housing for accommodating a radiation detecting member, has a first plate member to which radiation is incident from an outside of the housing; a second plate member arranged opposite to the first plate member; a radiation detecting member provided between the first plate member and the second plate member and having a radiation receiving surface to detect the radiation having passed through the first plate member; and a scattering radiation shielding member arranged at a radiation receiving surface side of the radiation detecting member and to eliminate scattering radiation from the radiation before the radiation is detected by the radiation receiving surface.

PATENT DESCRIPTION
BACKGROUND OF THE INVENTION 
   The present invention relates to a radiation image reading apparatus, and particularly to a radiation image reading apparatus which is used in a radiation image information recording and reproducing system using a radiation detector. 
   From the past, a radiation image represented by an X-ray image is widely used for the disease diagnosis. As a method to obtain the radiation image, so-called radiography system by which the radiation which passes through the subject is irradiated onto a fluorescent substance layer which is called an intensifying screen of the radiation detector, and a visible ray emitted from this fluorescent substance layer is irradiated onto the a silver halide photosensitive material (hereinafter, called “photosensitive material”), and a developing processing is conducted on this photosensitive material and a visible image is obtained, is proposed and put into practical use. 
   In recent years, instead of the radiography system, a radiation image recording and reproducing system in which the irradiated radiation energy is accumulated and recorded, and the radiation detector having a “stimulable phosphor” which stimulably emits corresponding to the accumulated and recorded radiation energy, when exciting light is irradiated, is used, is proposed. This system is structured in such a manner that, when the radiation transmitted the subject, is irradiated onto the sheet-like stimulable phosphor, after the radiation energy (hereinafter, called “image information”) corresponding to the radiation transmittance density of each portion of the subject, is accumulated and recorded into the stimulable phosphor, the image information accumulated and recorded in the stimulable phosphor is emitted by the exciting light as the stimulable emission light, and the intensity of this stimulable emission light is converted into an electric signal, and through the image recording material such as the photosensitive material or an image display apparatus such as a CRT, it is reproduced as a visible image. 
   Sheet-like stimulable phosphor (hereinafter, called “stimulable phosphor sheet”)  500  is, as shown in  FIG. 37 , in many cases, arranged in a housing  520  in the condition that it is fixed on a predetermined supporting plate  510 , and used for the radiation image radiographing, and after the radiation image radiographing is completed, the image information accumulated in the stimulable phosphor is read out by a radiation image reading means (hereinafter, called “reading means”)  530  provided in the housing  520 . The radiation image radiographing apparatus provided with such a reading means  530  is called the “radiation image reading apparatus”. 
   As the reading means  530 , as shown in  FIG. 37 , a means arranged on the rear surface side (opposite side to the radiation source) of the stimulable phosphor sheet  500  is proposed, and put in practical use. This reading means is provided with an exciting light source  531 , light guiding means  532 , and photoelectric conversion means  533 , and the image information accumulated on the stimulable phosphor sheet  500  is emitted as the stimulable emission light from the rear surface side by the exciting light irradiated from the exciting light source  531 , and the stimulable emission light is guided to the photoelectric conversion means  533  through the light guiding means  532  and converted into an electric signal. This electric signal is transferred to an image processing means, not shown, and the image processing is conducted, and visualized. 
   When the radiation image reading apparatus provided with the reading means  530  which reads out the stimulable emission light emitted from the rear surface side (opposite side to the radiation source) of such the stimulable phosphor sheet  500 , is used, there is a following problem. 
   That is, on the radiation source  600  side of the stimulable phosphor sheet  500 , as shown in  FIG. 38 , there exist the subject, front plate  521  of housing  520 , and supporting plate  510  (in the order from the radiation source  600 ), and stimulable phosphor sheet  500  accumulates also the radiation (scattering ray) of the low energy scattered when the radiation passes through them. When the accumulation of the accurate image information is hindered by such the scattering ray, there is a case where various harmful influences such as the lowering of the diagnostic performance are caused. 
   Particularly, when the subject  700  is arranged above such a radiation image reading apparatus and the radiographing is conducted (that is, in the case of the radiographing at the “lying position”), because it is necessary that a top board  800  supporting the weight of the subject  700  is provided between the subject  700  and the front plate  521  of the housing  520  (refer to  FIG. 39 ), a bad effect in which the scattering ray gives to the radiation image, is larger. 
   As a means for shielding such the scattering ray, conventionally, a “grid” structured in such a manner that a laminating body in which a radiation absorption layer formed of lead having the high radiation absorption factor and a radiation transmitting layer formed of aluminum, paper, wood, and synthetic resin which have the low radiation absorption factor are alternately provided, is covered by a cover member having the low radiation absorption factor, is used, and the scattering ray is shielded by arranging the grid in the vicinity of the subject  700  side. 
   However, because there is a case where the radiation is scattered also by a member constituting the grid or grid itself, there is a case where the accurate accumulation and recording of the image information which reaches the stimulable phosphor sheet are hindered. 
   Further, in the recent years, instead of the radiography system, a radiation image radiographing system by which the radiation detector such as a semiconductor sensor is used and the radiation image is radiographed, the radiation image is converted into the electric signal (image signal), and the electric signal (image signal) is image-processed and displayed on the CRT, is proposed. 
   A radiation image radiographing apparatus used in the radiation image radiographing system is, generally, provided with the housing fixed at a predetermined position and the radiation detector housed in this housing, and the radiation which is irradiated from the radiation source and passing through the subject and the front plate of the housing, is detected by the radiation detector. The radiation detector is provided with the conversion means for converting the detected radiation into the electric signal (image signal), and the electric signal (image signal) converted corresponding to the level of the detected radiation is sent to the image processing means, and herein, a predetermined image processing is conducted and it is outputted to the image display means such as the CRT, and displayed. 
   According to the radiation image radiographing system using the radiation image radiographing apparatus, the very broader range radiation can be detected as compared with the radiographing method, and the radiation image with an abundant amount of information can be obtained. 
   However, the radiation detector housed in the radiation image radiographing apparatus detects even the radiation (scattering ray) of the low energy scattered on each kind of members until the radiation is absorbed in the radiation absorption layer and detected. When the detection of the accurate image signal is hindered by such the scattering ray, there is a case where the various harmful influences such as the lowering of the diagnostic performance are caused. 
   The object of the present invention is to provide a radiation image radiographing apparatus by which the scattering ray is effectively shielded, and the image quality of the radiation image can be largely increased. 
   SUMMARY OF THE INVENTION 
   A radiographing cassette having a housing for housing a stimulable phosphor sheet described in Item 1-1 of the present invention is characterized in that there is provided a scattering radiation shielding grid on the reverse side of a front plate of the housing, and there is provided the stimulable phosphor sheet in contact with the scattered radiation shielding grid. 
   In the invention described in Item 1-1, since there is provided the grid for shielding the radiation (scattered radiation), having lower leveled energy that is generated when the radiographing is performed, on the reverse side of the front plate of the radiographing cassette, it is possible to prevent image information based on the scattered radiation from being accumulated and recorded on the stimulable phosphor sheet, and further, since the stimulable phosphor sheet is in contact with the grid, image information based on the radiation is accumulated and recorded on the stimulable phosphor sheet, in the step that the scattering of the scattered radiation caused by the grid itself is small, and thereby, it is possible to accumulate and record more correct image information. 
   The invention described in Item 1-2 is characterized in that the front plate of the above-mentioned housing is formed with a scattering radiation shielding grid, and the stimulable phosphor sheet is provided to be in contact with the reverse side of the front plate, in the radiographing cassette having the housing for housing the stimulable phosphor sheet. 
   In the invention described in Item 1-2, since the front plate itself of the radiographing cassette is represented by the grid, a primary factor for generating the scattered radiation is less and the scattering radiation is less generated. Further, since the generated radiation is shielded by the grid and the stimulable phosphor sheet is in contact with the grid, image information based on the radiation is accumulated and recorded on the stimulable phosphor sheet, in the step that the scattering of the scattering radiation generated by the grid itself is less, and thereby, it is possible to accumulate and record more correct image information. 
   The invention described in Item 1-3 is characterized in that the above-mentioned housing is composed of a housing main body having an opening section, the front plate for covering the opening section, and the stimulable phosphor sheet is in contact with the above-mentioned scattered radiation shielding grid, and can be separated from the housing main body together with the front plate, in the radiographing cassette described in Item 1-1 or 1-2. 
   In the invention described in Item 1-3, since the stimulable phosphor sheet, being in close contact with the grid, is separated from the housing main body, with the front plate, the stimulable phosphor sheet can be supported by the grid, and thereby, it is prevented from being damaged by the case that the stimulable phosphor sheet is bent, when the stimulable phosphor sheet after the radiographing is handled out of the radiographing cassette. 
   The invention described in Item 1-4 is represented by a radiation image reading apparatus employing the radiographing cassette described in either one of Items 1-1 to 1-3, wherein there are provided, an irradiating means for irradiating exiting light on the surface opposite to the radiation irradiated surface of the above-mentioned stimulable phosphor sheet, and a reading means for reading the above-mentioned radiation image from the stimulable phosphor sheet, by detecting stimulation light generated based on the exiting light irradiated by the irradiating means. 
   The invention described in Item 1-4 can read image information, accumulated and recorded on the stimulable phosphor sheet, under the condition that the grid is provided and the influence of the scattered radiation is small, on the surface opposite to the radiation-irradiated surface of the stimulable phosphor sheet. 
   The invention described in Item 1-5 is characterized in that there is provided a stimulable phosphor sheet take-up means which takes up the stimulable phosphor sheet from the radiographing cassette, in the radiation image reading apparatus described in Item 1-4. 
   Since the invention described in Item 1-5 can take up the stimulable phosphor sheet provided on the grid in the radiographing cassette, the stimulable phosphor sheet after the radiographing can be handled out of the radiographing cassette, and thereby, various means can be employed to read image information. 
   The invention described in Item 1-6 is represented by a radiation image reading method in the radiation image reading apparatus, described in Item 1-4 or 1-5, wherein exciting light is irradiated on the surface opposite to the surface of the above-mentioned stimulable phosphor sheet where the radiation having used for recording the radiation image is irradiated, and the above-mentioned radiation image can be read from the stimulable phosphor sheet, by the detection of the stimulation light generated based on the exiting light. 
   The invention described in Item 1-6 can read image information accumulated and recorded on the stimulable phosphor sheet, on the surface opposite to the surface where the radiation is irradiated to the stimulable phosphor sheet, under the condition that the stimulable phosphor sheet is provided on the grid and the influence of the scattered radiation is small. 
   The invention described in Item 2-1, represented by a radiographing cassette having a housing for housing a stimulable phosphor sheets, is characterized in that there is provided a metallic layer composed of a metal whose atomic number is not less than 20 or an alloy whose effective atomic number is not less than 20, between a front plate of the above-mentioned housing and the stimulable phosphor sheet, and an average radiation transmittance on a local part of 1 mm 2  sampled from the surface of the metallic layer optionally is from 1/10 to 10 times that on the total area on the metallic surface, and further the thickness of the metallic layer is in a range of 5 μm–200 μm. 
   In the invention described in Item 2-1, since there is provided the metallic layer that is composed of a specific metallic material and has the specific radiation transmittance and the thickness, between the front plate and the stimulable phosphor sheet, it is possible to shield effectively the radiation (scattered radiation), having low energy, which is scattered when transmitting through the subject. Accordingly, it is possible to improve the image quality of the radiation image remarkably. 
   The invention described in Item 2-2 is characterized in that an average radiation transmittance on a local part of 1 mm 2  sampled from the surface of the metallic layer optionally is ½ to 2 times that on the total area on the metallic layer, in the radiographing cassette described in Item 2-1. 
   The invention described in Item 2-3 is characterized in that the metallic layer is fixed to the reverse side of the front plate, in the radiographing cassette described in Item 2-1 or 2-2. 
   The invention described in Item 2-4 is characterized in that the metallic layer is composed of at least either one of Cu, Ni, Fe, Pb, Zn, W, Mo, Au, Ag, Ba, Ta, Cd, Ti, Zr, V, Nb, Cr, Co, and Sn, in the radiographing cassette described in Item 2-1, 2-2 or 2-3. 
   The invention described in Item 2-5 is characterized in that the metallic layer is composed of at least either one of Cu, Ni, Fe, Pb, and Zn, in the radiographing cassette described in Item 2-1, 2-2, or 2-3. 
   The invention described in Item 2-6 is characterized in that the thickness of the metallic layer is not less than 5 μm and not greater than 50 μm, in the radiographing cassette described in Item 2-1, 2-2, 2-3, 2-4, or 2-5. 
   The invention described in Item 2-7 is characterized in that the metallic layer has a columnar structure, in the radiographing cassette described in Item 2-1, 2-2, 2-3, 2-4, 2-5, or 2-6. 
   The invention described in Item 2-8 is characterized in that the metallic layer is produced by an electrolyte method, in the radiographing cassette described in Item 2-1, 2-2, 2-3, 2-4, 2-5, 2-6 or 2-7. 
   The invention described in Item 2-9 is characterized in that a synthetic resin thin film is laminated on at least one of the surfaces of the metallic layer, in the radiographing cassette described in Item 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7 or 2-8. 
   The invention described in Item 2-10 is characterized in that the front plate is a hard one composed of at least either one material of carbon fiber reinforced resin, acrylic resin, phenol resin, polyimide resin, or aluminum, in the radiographing cassette described in Item 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8 or 2-9. 
   An electronic cassette for radiographic imaging, having a flat type radiation detecting means for detecting the radiation and a flat housing for covering the radiation detecting means, of the invention described in Item 3-1 is characterized in that there is provided a metallic layer composed of a metal whose atomic number is not less than 20 or an alloy whose effective atomic number is not less than 20, between a front plate of the above-mentioned housing and the stimulable phosphor sheet, and an average radiation transmittance on a local part of 1 mm 2  sampled from the surface of the metallic layer optionally is 1/10 to 10 times that on the total area on the metallic surface, and further the thickness of the metallic layer is not less than 5 μm and not larger than 200 μm. 
   In the invention described in Item 3-1, since there is provided the metallic layer that is composed of a specific metallic material and has the specific radiation transmittance and the thickness, between the front plate of the housing and the radiation detecting means, it is possible to shield evenly and effectively the radiation (scattering radiation) having low energy. Accordingly, it is possible to improve the image quality of the radiation image remarkably. 
   The invention described in Item 3-2 is characterized in that an average radiation transmittance on a local part of 1 mm 2  sampled from the surface of the metallic layer optionally is ½ to 2 times that on the total area on the metallic surface, in the electronic cassette for radiographic imaging described in Item 3-1. 
   The invention described in Item 3-3 is characterized in that the metallic layer is fixed to the reverse side of the front plate, in the electronic cassette for radiographic imaging described in Item 3-1 or 3-2. 
   The invention described in Item 3-4 is characterized in that the metallic layer is composed of at least either one of Cu, Ni, Fe, Pb, Zn, W, Mo, Au, Ag, Ba, Ta, Cd, Ti, Zr, V, Nb, Cr, Co, and Sn, in the electronic cassette for radiographic imaging described in Item 3-1, 3-2 or 3-3. 
   The invention described in Item 3-5 is characterized in that the metallic layer is composed of at least either one of Cu, Ni, Fe, Pb, and Zn, in the electronic cassette for radiographic imaging described in Item 3-1, 3-2, 3-3 or 3-4. 
   The invention described in Item 3-6 is characterized in that the thickness of the metallic layer is not less than 5 μm and not greater than 50 μm, in the electronic cassette for radiographic imaging described in Item 3-1, 3-2, 3-3, 3-4, or 3-5. 
   The invention described in Item 3-7 is characterized in that the metallic layer has a columnar structure, in the electronic cassette for radiographic imaging described in Item 3-1, 3-2, 3-3, 3-4, 3-5, or 3-6. 
   The invention described in Item 3-8 is characterized in that the metallic layer is produced by an electrolyte method, in the electronic cassette for radiographic imaging described in Item 3-1, 3-2, 3-3, 3-4, 3-5, 3-6 or 3-7. 
   The invention described in Item 3-9 is characterized in that a synthetic resin thin film is coated on at least one of the surfaces of the metallic layer, in the electronic cassette for electronic imaging described in Item 3-1, 3-2, 3-3, 3-4, 3-5, 3-6, 3-7 or 3-8. 
   The invention described in Item 3-10 is characterized in that the front plate is a hard one made of at least either one material of carbon fiber reinforced resin, acrylic resin, phenol resin, polyimide resin, or aluminum, in the electronic cassette for radiographic imaging described in Item 3-1, 3-2, 3-3, 3-4, 3-5, 3-6, 3-7, 3-8 or 3-9. 
   The invention described in Item 4-1 is a radiation image reading apparatus, having therein a supporting plate, a stimulable phosphor sheet arranged on the side opposite to the radiation-irradiated side on the supporting plate, and a reading means for reading stimular phosphor light emitted from the stimulable phosphor sheet, in which the stimulable phosphor sheet is irradiated by the radiation, that has passed through the subject and the supporting plate successively, and radiation image information recorded on the stimulable phosphor sheet based on the energy of the irradiated radiation is read, wherein the supporting plate is formed of a scattered radiation shielding grid, and the scattered radiation shielding grid and the stimilable phosphor sheet are provided to be in contact with each other. 
   In the invention described in Item 4-1, the scattering radiation shielding grid supports and holds the stimulable phosphor sheet, and further prevents the image information, caused by the radiation (scattering radiation) having lower energy generated when the radiographing is performed on the stimulable phosphor sheet, from being accumulated and recorded on the stimulable phosphor sheet. Especially, since the supporting plate is not required by making the grid to be the supporting plate, the scattered radiation generated by the supporting plate is reduced, and the influence of the scattered radiation is further reduced. Further, since the stimulable phosphor sheet is in contact with the grid, image information based on the radiation is accumulated and recorded on the stimulable phosphor sheet, in the stage where scattering of the scattering radiation caused by the grid itself is less, and thereby, it is possible to obtain correct image information by reading the image information accumulated and recorded. 
   The present invention mentioned in Item 4-2 is characterized in that the stimulable phosphor sheet is coated with a moisture-proof protective film, in the radiation image reading apparatus described in Item 4-1. 
   Needless to say, the invention described in Item 4-2 can obtain the effect same as the effect of the invention described in Item 4-1, and especially, it is possible to prevent that moisture such as humidity and a stain are stuck to the stimulable phosphor sheet and that a crack is caused on the stimnlable phosphor sheet itself, because the stimulable phosphor sheet is coated by the moisture-proof protective film. 
   The present invention mentioned in Item 4-3 is characterized in that the scattered radiation shielding grid and the stimulable phosphor sheet are cemented each other through a resin film, in the radiation image reading apparatus described in Item 4-1 or 4-2. 
   The invention described in Item 4-4 is characterized in that the stimular phosphor light is read from the surface opposite to the surface of the stimulable phosphor sheet irradiated by radiation, in the radiation image reading apparatus described in either one of Items 4-1, 4-2 or 4-3. 
   The invention described in Item 5-1 is represented by a radiation image reading apparatus, having therein, a supporting plate, a stimulable phosphor sheet arranged at the side opposite to the radiation-irradiated side of the supporting plate, and a reading means for reading a stimulable emission light emitted from the stimulable phosphor sheet, in which the radiation, that has passed through the subject and the supporting plate successively, is irradiated on the stimulable phosphor sheet, and radiation image information, accumulated on the stimulable phosphor sheet based on the energy of the irradiated radiation, is read as the stimular phosphor light wherein there is provided a metallic layer that is composed of a metal whose atomic number is not less than 20 or an alloy whose effective atomic number is not less than 20, at the position that is closer to the subject than from the stimulable phosphor sheet, and an average radiation transmittance on a local part of 1 mm 2  sampled from the surface of the metallic layer optionally is from 1/10 to 10 times that on the total area on the metallic surface, further the thickness is in a range of 5 μm–200 μm. 
   In the invention described in Item 5-1, since there is provided a metallic layer that is composed of a specific metallic material and has the specific radiation transmittance and the thickness, at the position that is closer to the subject than the stimulable phosphor sheet, it is possible to shield effectively the radiation (scattered radiation), having low energy, which is scattered when transmitting through the subject. Accordingly, it is possible to improve the image quality of the radiation image remarkably. 
   The invention described in Item 5-2 is characterized in that a metallic layer is arranged between the supporting plate and the stimulable phosphor sheet, in the radiation image reading apparatus described in Item 5-1. 
   The invention described in Item 5-3 is characterized in that the stimulable phosphor sheet is fixed to the supporting plate under the condition that the both sides of the stimulable phosphor sheet are coated by a moisture-proof protective film, and the metallic layer is provided in the moisture-proof protective film arranged on the supporting plate side, in the radiation image reading apparatus described in Item 5-1 or 5-2. 
   The invention described in Item 5-4 is characterized in that an average radiation transmittance on a local part of 1 mm 2  sampled from the surface of the metallic layer optionally is from ½ to 2 times that on the total area on the metallic surface, in the radiation image reading apparatus described in Item 5-1, 5-2 or 5-3. 
   The invention described in Item 5-5 is characterized in that the metallic layer is made of at least either one of Cu, Ni, Fe, Pb, Zn, W, Mo, Au, Ag, Ba, Ta, Cd, Ti, Zr, V, Nb, Cr, Co, and Sn, in the radiation image reading apparatus described in Item 5-1, 5-2, 5-3 or 5-4. 
   The invention described in Item 5-6 is characterized in that the metallic layer is made of at least either one of Cu, Ni, Fe, Pb, and Zn, in the radiation image reading apparatus described in Item 5-1, 5-2, 5-3, or 5-4. 
   The invention described in Item 5-7 is characterized in that the metallic layer is made of at least either one of Cu, Ni and Fe, in the radiation image reading apparatus described in Item 5-1, 5-2, 5-3, or 5-4. 
   The invention described in Item 5-8 is characterized in that the thickness of the metallic layer is not less than 5 μm and not greater than 50 μm, in the radiation image reading apparatus described in Item 5-1, 5-2, 5-3, 5-4, 5-5, 5-6 or 5-7. 
   The invention described in Item 5-9 is characterized in that the metallic layer has a columnar structure, in the radiation image reading apparatus described in Item 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-7 or 5-8. 
   The invention described in Item 5-10 is characterized in that the metallic layer is produced by an electrolyte method, in the radiation image reading apparatus described in Item 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-7, 5-8 or 5-9. 
   The invention described in Item 5-11 is characterized in that the front plate is a hard one made of at least either one material of acrylic resin, phenol resin, polyimide resin, carbon fiber reinforced synthetic resin or aluminum, in the radiation image reading apparatus described in Item 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-7, 5-8, 5-9 or 5-10. 
   The invention described in Item 5-12 is characterized in that the reading means reads the stimulable emission light emitted from the both sides of the stimulable phosphor sheet, in the radiation image reading apparatus described in Item 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-7, 5-8, 5-9, 5-10 or 5-11. 
   The invention described in Item 6-1 is represented by a radiation image radiographing apparatus having therein a flat type radiation detecting means for detecting the radiation and a housing for covering the radiation detecting means, wherein there is provided a metallic layer made of a metal whose atomic number is not less than 20 or an alloy whose effective atomic number is not less than 20, between the front plate of the above-mentioned housing and the radiation detecting means, and an average radiation transmittance on a local part of 1 mm 2  sampled from the surface of the metallic layer optionally is from 1/10 to 10 times that on the total area on the metallic surface, and further, the thickness is not less than 5 μm and not greater than 200 μm. 
   In the invention described in Item 6-1, since there is provided the metallic layer that is made of a specific metallic material and has the specific radiation transmittance and the thickness, between the front plate of the housing and the radiation detecting means, it is possible to shield the radiation (scattered radiation) having low energy, effectively to be in an even condition. Accordingly, it is possible to improve the image quality of the radiation image remarkably. 
   The invention described in Item 6-2 is characterized in that an average radiation transmittance on a local part of 1 mm 2  sampled from the surface of the metallic layer optionally is from ½ to 2 times that on the total area on the metallic surface, in the radiation image radiographing apparatus described in Item 6-1. 
   The invention described in Item 6-3 is characterized in that the metallic layer is fixed to the reverse side of the front plate, in the radiation image radiographing apparatus described in Item 6-1 or 6-2. 
   The invention described in Item 6-4 is characterized in that the metallic layer is made of at least either one of Cu, Ni, Fe, Pb, Zn, W, Mo, Au, Ag, Ba, Ta, Cd, Ti, Zr, V, Nb, Cr, Co, and Sn, in the radiation image radiographing apparatus described in Item 6-1, 6-2 or 6-3. 
   The invention described in Item 6-5 is characterized in that the metallic layer is made of at least either one of Cu, Ni, Fe, Pb, and Zn, in the radiation image radiographing apparatus described in Item 6-1, 6-2, 6-3 or 6-4. 
   The invention described in Item 6-6 is characterized in that the thickness of the metallic layer is not less than 5 μm and not greater than 50 μm, in the radiation image radiographing apparatus described in Item 6-1, 6-2, 6-3, 6-4 or 6-5. 
   The invention described in Item 6-7 is characterized in that the metallic layer has a columnar structure, in the radiation image radiographing apparatus described in Item 6-1, 6-2, 6-3, 6-4, 6-5, or 6-6. 
   The invention described in Item 6-8 is characterized in that the metallic layer is produced by an electrolyte method, in the radiation image radiographing apparatus described in Item 6-1, 6-2, 6-3, 6-4, 6-5, 6-6 or 6-7. 
   The invention described in Item 9-9 is characterized in that a synthetic resin thin film is laminated on at least one of the surfaces of the metallic layer, in the radiation image radiographing apparatus described in Item 6-1, 6-2, 6-3, 6-4, 6-5, 6-6, 6-7 or 6-8. 
   The invention described in Item 6-10 is characterized in that a front plate is a hard one made of at least either one material of carbon fiber reinforced resin, acrylic resin, phenol resin, polyimide resin, or aluminum, in the radiation image radiographing apparatus described in Item 6-1, 6-2, 6-3, 6-4, 6-5, 6-6, 6-7, 6-8 or 6-9. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram of an X-ray radiation image reading apparatus related to the first embodiment of the present invention. 
       FIG. 2  is an enlarged drawing of part II of  FIG. 1 . 
       FIG. 3  is an enlarged section of a grid related to the embodiment of the present invention. 
       FIG. 4  is a schematic diagram of an X-ray image reading apparatus related to the second embodiment of the present invention. 
       FIG. 5  is an enlarged section of part V of  FIG. 4 . 
       FIG. 6  is a schematic diagram of an X-ray image reading apparatus related to the third embodiment of the present invention. 
       FIG. 7  is an enlarged section of part VII of  FIG. 6 . 
       FIG. 8  is a schematic perspective view of a cassette related to the fourth embodiment of the present invention. 
       FIG. 9(   a ) is a section taken on line A—A in  FIG. 8 . 
       FIG. 9(   b ) is an enlarged drawing of part  2 B of  FIG. 9(   a ). 
       FIG. 10  is an enlarged section of a grid related to the embodiment of the present invention. 
       FIG. 11(   a ) is a schematic diagram of a radiation image reading apparatus related to the fourth embodiment of the present invention. 
       FIG. 11(   b ) is an enlarged drawing of part  104 B of  FIG. 11(   a ). 
       FIG. 12  is a schematic perspective view of a cassette related to the fifth embodiment of the present invention. 
       FIG. 13(   a ) is a section taken on line B—B in  FIG. 12 . 
       FIG. 13(   b ) is an enlarged drawing of part  6 B of  FIG. 13(   a ). 
       FIG. 14(   a ) is a schematic diagram of a radiation image reading apparatus related to the fifth embodiment of the present invention. 
       FIG. 14(   b ) is an enlarged drawing of part  107 B of  FIG. 14(   a ). 
       FIG. 15(   a ) is a schematic diagram of a variation of a radiation image reading apparatus related to the fifth embodiment of the present invention. 
       FIG. 15(   b ) is an enlarged drawing of part  108 B of  FIG. 15(   a ). 
       FIG. 16  is a schematic perspective view of a cassette related to the sixth embodiment of the present invention. 
       FIG. 17(   a ) is a section taken on line C—C in  FIG. 16 . 
       FIG. 17(   b ) is an enlarged drawing of part  110 B of  FIG. 17(   a ). 
       FIG. 18(   a ) is a schematic diagram of a radiation image reading apparatus related to the sixth embodiment of the present invention. 
       FIG. 18(   b ) is an enlarged drawing of part  111 B of  FIG. 18(   a ). 
       FIG. 19  is an example in which metallic foil is employed instead of a grid in  FIG. 2  in the seventh embodiment of the present invention. 
       FIGS. 20(   a ) and  20 ( b ) are for the purpose of explaining radiation transmittance for metallic foil,  FIG. 20(   a ) is a conceptual drawing showing a local part of 1 mm 2  sampled from the surface of the metallic foil optionally, and  FIG. 20(   b ) is a graph showing an average radiation transmittance in each local part. 
       FIG. 21  is a conceptual drawing for illustrating a producing method (electrolytic solution method) of the metallic foil. 
       FIG. 22  is an enlarged section showing a columnar structure of the metallic foil. 
       FIG. 23  is an example wherein the metallic foil is employed instead of the grid in  FIG. 5   
       FIG. 24  is an enlarged section of the condition that a synthetic resin film is laminated on the metallic foil of the X-ray image reading apparatus shown in  FIG. 23 . 
       FIG. 25  is an example wherein the metallic foil is employed instead of the grid in  FIG. 7 . 
       FIG. 26  is a schematic perspective view of a cassette related to the embodiment of the present invention. 
       FIG. 27(   a ) is an enlarged section taken on line II—II section in  FIG. 26 . 
       FIG. 27(   b ) is an enlarged drawing of part  2 B of  FIG. 27(   a ). 
       FIGS. 28(   a ) and  28 ( b ) are for the purpose of explaining radiation transmittance for metallic foil of the cassette shown in  FIG. 26 , and  FIG. 28(   a ) is a conceptual drawing showing a local part of 1 mm 2  sampled from the surface of the metallic foil optionally, while  FIG. 28(   b ) is a graph showing an average radiation transmittance in each local part. 
       FIG. 29  is a schematic diagram of an X-ray image radiographing apparatus related to the eighth embodiment of the invention. 
       FIG. 30  is an enlarged section of part II in  FIG. 29 . 
       FIG. 31  is an enlarged section of the condition that a synthetic resin film is coated on the metallic foil of the X-ray image reading apparatus shown in  FIG. 29 . 
       FIG. 32  is an enlarged section in the case of an occasion wherein the other X-ray detecting device is provided on the X-ray image padiographing apparatus, shown in  FIG. 29 . 
       FIG. 33  is a schematic perspective view of an electronic cassette related to the ninth embodiment of the present invention. 
       FIG. 34  is an enlarged section taken on line II—II in  FIG. 33 . 
       FIG. 35  is an enlarged section of the condition that a synthetic resin film is laminated on the metallic foil of the electronic cassette shown in  FIG. 33 . 
       FIG. 36  is an enlarged section of the case wherein the other X-ray detecting device is provided on the electronic cassette shown in  FIG. 33 . 
       FIG. 37  is a schematic diagram of a conventional radiation image reading apparatus of a standing position type. 
       FIG. 38  is an enlarged section of part IX of  FIG. 37 . 
       FIG. 39  is a schematic diagram of a conventional radiation image reading apparatus of a lying position type. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings, the embodiments of the present invention will be detailed below. In the present embodiment, an X-ray image reading apparatus (radiation image reading apparatus) used in the “radiation image information recording and reproducing system” by which an X-ray transmitted the subject is irradiated onto the stimulable phosphor sheet, and the image information is accumulated and recorded, will be described. 
   (The First Embodiment) 
   The X-ray image reading apparatus  10  according to the present embodiment is, as shown in  FIG. 1  and  FIG. 2 , used for the X-ray radiographing at the standing position, and provided with housing  11 , grid  12 , exciting light source  13 , light guiding means  14 , photoelectric conversion means  15 , erasing means  16 , image processing means  17 , image output means  18 , and stimulable phosphor sheet  19 . The exciting light source  13 , light guiding means  14 , and photoelectric conversion means  15  are arranged on the rear surface side of the stimulable phosphor sheet  19  (opposite side to the X-ray irradiation side), and they structure a reading means for reading the stimulable emission light from the rear surface side of the stimulable phosphor sheet  19 . 
   The housing  11  protects each device mounted in its inside, and together with that, it is a housing which prevents that, after the radiographing, the light is irradiated onto the stimulable phosphor sheet  19  and the accumulated and recorded image information is vanished. In the case of the X-ray radiographing, because it is conducted by irradiating the X-ray which is irradiated from an X-ray source  30  and passes through a subject  40  and the front plate  11   a  of the housing  11 , onto the stimulable phosphor sheet  19 , the front plate  11   a  of the housing  11  is made of the material whose X-ray transmission factor is high. In this connection, in order not to hinder the transmission of the X-ray, it is preferable that the thickness of the front plate  11   a  is about 1–5 mm. Further, it is preferable that, in order to surely protect an each kind of devices mounted in its inside, the housing  11  is made of the material whose rigidity is comparatively high. 
   As the material whose X-ray transmission factor is high and rigidity is high, aluminum, carbon fiber reinforced resin, acrylic resin, phenol resin, polyimide resin, and composite material of these resins and aluminum, can be listed. In the present embodiment, as the material of the housing  11 , the carbon fiber reinforced resin is adopted. 
   The grid  12  is used as a means for shielding the radiation (scattered ray) of the low energy scattered when it passes through the material such as the subject. The grid  12  is, for example, as shown in  FIG. 3 , structured in such a manner that a lamination body in which the radiation absorption layer  12   a  formed of lead with the high radiation absorption factor, and the radiation transmission layer  12   b  formed of aluminum, wood, synthetic resin with the low radiation absorption factor, are alternately provided, is covered by the cover member  12   c  with the low radiation absorption factor. In the radiation to pass through the grid  12 , because the straight advancing component easily passes through, and the scattering ray hardly passes through, as the result, the scattering ray is shielded. 
   The grid  12  is fixed in the vicinity of the front plate  11   a  of the housing  11 , and also has a function as the supporting body to almost perpendicularly support the stimulable phosphor sheet  19  to the irradiation direction of the X-ray, and in the present embodiment, the stimulable phosphor sheet  19  is fixed on the opposite side surface to the X-ray irradiation side of the grid  12  (refer to  FIGS. 1 and 2 ). 
   The stimulable phosphor sheet  19  is the sheet in which the stimulable phosphor  19   b  is laminated on the sheet-like supporting body  19   a  (refer to  FIG. 2 ). It is preferable that the sheet-like supporting body  19   a  is, for the operation, made of a material having the flexibility such as wool, cotton, paper, or plastic film. The stimulable phosphor  19   b  is a material which accumulates the irradiated X-ray energy and, when the exciting light is irradiated, emits the stimulative ray corresponding to the accumulated X-ray energy. 
   As the stimulable phosphor  19   b , rare-earth activated strontium sulfide fluorescent substance, or rare-earth activated lanthanum oxy-sulfide fluorescent substance, disclosed in U.S. Pat. No. 3,859,527, rare-earth activated alkaline earth metal fluoro-halide fluorescent substance, disclosed in U.S. Pat. No. 4,236,078 or Japanese Tokkaihei No. 8-265525, rare-earth activated lanthanum oxy-halide fluorescent substance, disclosed in Japanese Tokkaisho No. 55-12144, copper and/or lead activated zinc sulfide, rare-earth activated alumina.barium oxide or silica.alkaline earth metal oxide fluorescent substance, disclosed in Japanese Tokkaisho No. 55-12142, can be listed. 
   The stimulable phosphor sheet  19  in the present embodiment is adhered to the grid  12  (through an adhesive agent, not shown) in the situation that its both surfaces are coated by a moisture-proof protective film  20  as a moisture proof-protective film (refer to  FIG. 2 ). The moisture proof protective film  20  performs the function to prevent the water from invading into the stimulable phosphor sheet. It is preferable that this moisture-proof protective film  20  is a film having the high X-ray transmission factor and transparency so that the transmittance of the X-ray, exciting light or stimulable emission light is not prevented. 
   As the moisture proof protective film  20  having such a characteristic, a resin film such as a polyethylene film, polypropylene film, vinyl chloride resin film, polyethylene terephthalate film, polymethacrylate film, nitrocellulose film, or cellulose acetate film, and their laminated body, and a film in which a thin film such as metal oxide, or silicon nitride is evaporated on these films, can be listed. In the present embodiment, as a moisture-proof protective film  20 , a film in which metal oxide is evaporated on the polyethylene terephthalate film, is adopted, and it is arranged on both surfaces of the stimulable phosphor sheet  19 , and thermal fusing is conducted on its outside edge. 
   In this connection, this protective film may also be different on the X-ray irradiation side and exciting light irradiation side, and on the X-ray irradiation side, a very thin metallic thin film which does not prevent the X-ray transmission, can also be used. 
   The exciting light source  13  performs the function by which the stimulable emission light corresponding to the accumulated and recorded image information, is emitted, by irradiating the exciting light onto the stimulable phosphor sheet  19 . The exciting light source  13  in the present embodiment is, by (not shown) drive mechanism, while it is reciprocated in the arrowed direction in  FIG. 1 , the exciting light can be irradiated onto the stimulable phosphor sheet  19 . 
   The light guiding means  14  functions to guide the stimulable emission light emitted from the stimulable phosphor sheet  19  to the photoelectric conversion means  15 , and is made of transparent acrylic plate. In this connection, the light guiding means  14  is reciprocated in timed relationship with the exciting light source  13 . 
   The photoelectric conversion means  15  detects the stimulable emission light emitted from the stimulable phosphor sheet  19 , and generates the electric signal corresponding to the light amount of the stimulable emission light. In the present embodiment, as the photoelectric conversion means  15 , the photo-multiplier is adopted. 
   The erasing means  16  functions such that, after the image information is read from the stimulable phosphor sheet  19  by the reading means composed of the exciting light source  13 , light guiding means  14  and photoelectric conversion means  15 , the radiation energy remaining in this stimulable phosphor sheet  19  is emitted. By this erasing means  16 , the new X-ray radiographing can be conducted. 
   The image processing means  17  obtains the digital image signal by A/D-converting the image information converted into the electric signal by the photoelectric conversion means  15 . 
   The image output means  18  outputs the digital image signal obtained by the image processing means  17  as the X-ray image. As this image output means  18 , other than a device displaying the X-ray image such as the CRT or liquid crystal display, a device to produce the hard-copy of the X-ray image, such as an ink jet printer, can be listed. 
   The image information of the X-ray which passes through the subject  40 , front plate  11   a  and further grid  12 , and which is accumulated and recorded on the stimulable phosphor sheet  19 , can be read by the X-ray radiographing in the radiation image reading apparatus  10  structured as described above. Particularly, because the grid and the stimulable phosphor sheet are in contact with each other, in the stage in which the scattering of the scattered ray generated by the grid itself is smaller, the image information according to the radiation is accumulated and recorded on the stimulable phosphor sheet, and by reading out the accumulated and recorded information, more accurate image information can be obtained. 
   Further, as described above, in the opposite surface to the surface on which radiation is irradiated on the stimulable phosphor sheet  19 , by reading out the image information, more accurate image information can be obtained. 
   That is for the reason that the difference is generated in the image information which is accumulated and recorded by the energy difference of the radiation component. The direct component of the image information in the radiation is the radiation with the straight advancing and comparatively high energy. Comparing with that, the scattering ray generated when the radiation collides with the material, is the radiation with comparatively low energy, and the radiation in which the image information is scattered and disturbed. Furthermore, when the grid  12  is provided, the energy of the scattered ray is more reduced. 
   To accumulate and record the image information on the stimulable phosphor sheet  19 , is that the energy of the radiation is absorbed in the stimulable phosphor sheet  19 , therefore, the high energy and straight advancing radiation can reach the rear side of the stimulable phosphor sheet  19 , and on the rear side, the image information can be accumulated and recorded. On the one hand, in the low energy scattering radiation, although the image information can be accumulated and recorded on the front side of the stimulable phosphor sheet  19 , the energy is absorbed before it reaches the rear side, and the component which reaches the rear side is small. Accordingly, because the image information of the rear side is the information in which the direct component of the image information is many (the scattering ray is small), more accurate image information can be obtained. 
   (The Second Embodiment) 
   An X-ray image reading apparatus according to the present embodiment is, as shown in  FIG. 4 , used for the X-ray radiographing at the lying position, and because the structure and function of the exciting light source  13 , reading means composed of the light guiding means  14  and photoelectric conversion means  15 , and erasing means  16 , and the material characteristic of the housing  11 , grid  12 , stimulable phosphor sheet  19 , and moisture-proof protective film  20 , are practically the same as those of the X-ray image reading apparatus according to the first embodiment, the description will be omitted. Further, because the practically same units can be adopted also for the image processing means  17  and image output means  18 , the illustration is neglected. 
   In the present embodiment, above the housing  11  of the X-ray image reading apparatus  10 , a top board  50  which supports the weight of the subject  40  is provided (refer to  FIG. 4 ). This top board  50  is structured by the material having the rigidity which can bear the weight of the subject  40  and the high X-ray transmission factor, and in the present embodiment, an acrylic plate is adopted. 
   By the x-ray radiographing in the thus structured radiation image reading apparatus  10 , the image information of the X-ray which passes through the subject  40 , top board  50 , and front plate  11   a  and further grid  12 , and which is accumulated and recorded on the stimulable phosphor sheet  19 , can be read. 
   Further, in the same as the first embodiment, on the surface opposite to the surface onto which the radiation is irradiated on the stimulable phosphor sheet  19 , by reading the image information, more accurate image information can be obtained. 
   (The Third Embodiment) 
   In the X-ray image reading apparatus relating to the present embodiment, as shown in  FIG. 6 , the stimulable phosphor sheet  19  is not fixed on the grid  12 , and circulated in the apparatus by a circulation conveying means  91 , and the image information accumulated on the stimulable phosphor sheet  19  is read out by the reading means provided on a circulation path, and erased by the erasing means  16 . 
   In this connection, in the present embodiment, because the structure and function of the erasing means  16 , image processing means  17  and image output means  18 , and the material characteristic of the housing  11 , grid  12 , and stimulable phosphor sheet  19 , are practically the same as in the X-ray image reading apparatus according to the first embodiment, the description will be neglected. 
   In the X-ray image reading apparatus according to the present embodiment, on the rear portion of the grid  12 , a pressure plate  22  by which the stimulable phosphor sheet  19  is pushed to the grid  12 , and temporarily held, is provided. This pressure plate  22  can be moved in the arrowed direction in  FIG. 6  by a drive mechanism, not shown, and the stimulable phosphor sheet  19  conveyed to the radiographing position between the grid  12  and pressure plate  22  can be temporarily held. 
   Further, the situation in which, by the grid  12  and pressure plate  22 , the stimulable phosphor sheet  19  is held at the radiographic position A, is shown in  FIG. 7 . 
   As shown in  FIG. 7 , after, onto the stimulable phosphor sheet  19  held at the radiographic position A by the grid and pressure plate  22 , the X-ray transmitted the subject is irradiated, and the X-ray radiographing is completed, the stimulable phosphor sheet  19  is conveyed to the reading position B by the circulation conveying means  91 . In the present embodiment, the light guiding means  14  and photoelectric conversion means  15  are arranged on the rear surface side (opposite side to the X-ray irradiation side) of the stimulable phosphor sheet  19  conveyed to the reading position B (refer to  FIG. 6 ), and the stimulable emission light emitted from the stimulable phosphor sheet  19  can be detected by the exciting light irradiated by the exciting light source  13 . 
   After the image information accumulated on the stimulable phosphor sheet  19  is read at the reading position B, it is conveyed again to the radiographing position A by the circulation conveying means  91 . In the present embodiment, because the erasing means  16  is provided on the path on which it is conveyed from the reading position B to the radiographing position A, the radiation energy remaining in the stimulable phosphor sheet  19  is emitted, and it can be used for a new X-ray radiographing. 
   By the X-ray radiographing in thus structured radiation image reading apparatus, the image information of the X-ray which passes through the subject  40 , front plate  11   a , and further, grid  12 , and which is accumulated and recorded, can be read. 
   Further, in the same manner as in the first embodiment, on the surface opposite to the surface on which the radiation is irradiated onto the stimulable phosphor sheet  19 , by reading the image information, more accurate image information can be obtained. Further, in this correspondence, the image information on the surface on which the radiation is irradiated, can also be read, and the layout of the light guiding means  14  can also be changed. 
   In this connection, in the embodiments described above, it is structured that an adhesive agent is used when the stimulable phosphor sheet  19  and the grid  12  are adhered, however, the present invention is not limited to this, but, it may also be the adhesion by a double-sided tape. Further, the structure of the radiation reading apparatus is also at will, and for the rest, of course, the specific detailed structure can also be appropriately changed. 
   Next, an embodiment in which the present invention is applied to a portable cassette type radiation detector, will be described. 
   (The Fourth Embodiment) 
   A cassette  110  according to the present embodiment is, as shown in  FIG. 8 , one whose plane shape is rectangular, and the front plate  111  is separably attached from a cassette case  112  as the housing main body. Further, as shown in  FIG. 9 , the cassette  110  is provided with the front plate  111 , grid  113 , stimulable phosphor sheet  120 , and cassette case  112 . The cassette  110  protects the stimulable phosphor sheet  120  at the time of the radiographing or conveying, and after the radiographing, prevents that the light is irradiated on the stimulable phosphor sheet  120  and the accumulated image information is vanished. 
   On the rear surface of the front plate  111 , the grid  113  is provided, and further, on the rear surface of the grid  113 , the stimulable phosphor sheet  120  is arranged being in contact with it. This front plate  111  is attached in such a manner that it covers an accommodation portion  112   x  of the cassette case  112 , and after the radiographing, when the light is irradiated on the stimulable phosphor sheet  120 , the function as a light shielding plate which prevents the accumulated image information from being vanished, is also performed. In the present embodiment, it is structured in such a manner that, when a guide groove  111 ′ is provided on the side surface of the front plate  111 , and a protrusion  112 ′ corresponding to the guide groove  111 ′ is respectively provided in the inside of the side surface of the cassette case  112 , the front plate  111  is slid to the cassette case  112  (refer to  FIG. 8  and  FIG. 9 ). 
   The X-ray radiographing is conducted in such a manner that the front plate  111  is attached to the cassette case  112 , the stimulable phosphor sheet  120  is accommodated in its accommodation portion  112   x , and the X-ray which passes through the subject  150  and front plate  111 , and further, grid  113 , is irradiated on the stimulable phosphor sheet  120  (refer to  FIG. 9(   a )). Therefore, the front plate  111  is made of the material whose X-ray transmission factor is high. Further, in order not to hinder the transmission of the X-ray, it is preferable that the thickness of this front plate  111  is about 1–5 mm. 
   Further, it is preferable that the front plate  111  is made of the material having the high rigidity in order to prevent the physical damage of the stimulable phosphor sheet  120 . As the material having the high X-ray transmission factor and high rigidity, aluminum, carbon fiber reinforced resin, acrylic resin, phenol resin, polyimide resin, and composite material of these resins and aluminum, can be listed. In the present embodiment, as the material of the front plate  111 , carbon fiber reinforced resin is adopted. 
   The cassette case  112  is provided with the accommodation portion  112   x  which accommodates the stimulable phosphor sheet  120 , and at the time of radiographing and conveying, prevents the stimulable phosphor sheet  120  from being damaged, and after the radiographing, prevents that, when the light is irradiated on the stimulable phosphor sheet  120 , the accumulated and recorded image information is vanished. 
   As the material of the cassette case  112 , when it has the rigidity of the degree in which the physical damage of the stimulable phosphor sheet  120  can be prevented, any material may be used, and each metal, synthetic resin, and fiber reinforced resin can be listed. 
   The stimulable phosphor sheet  120  in the present embodiment is attached to the front plate  111  (grid  113 ) by the fixing means, not shown, and following the slide motion of the front plate  111 , it is accommodated in, or taken out from the accommodation portion  112   x  of the cassette case  112  (refer to  FIG. 8  and  FIG. 9 ). The thickness of this stimulable phosphor sheet  120  can be appropriately determined corresponding to the accumulated X-ray amount, the kind of the stimulable phosphor, and the height of the accommodation portion  112   x  of the cassette case  112 . 
   Next, a radiation image reading apparatus using the cassette  110  in the fourth embodiment, and a method will be described. 
     FIG. 11   a  shows the main portion structure of the radiation image reading apparatus  180  according to the present embodiment, and it is the apparatus to read the image information accumulated and recorded on the stimulable phosphor sheet  120  accommodated in the cassette  110 . 
   The radiation image reading apparatus  180 , as shown in  FIG. 11   a , is provide with a cassette accommodation portion  180   a , image reading section  180   b , exciting light source  114  as the irradiating means, light guiding means  115 , photoelectric conversion means  116 , image processing means  117 , image output means  118 , and erasing means  119 . This radiation image reading apparatus  180  operates in such a manner that it conveys the front plate  111  from the cassette  110  accommodated in the cassette accommodation portion  180   a  to the image reading section  180   b  by the conveying means, not shown, next, after, from the stimulable phosphor sheet  120  provided on the front plate  111 , the image information is read, it returns the front plate  111  to the cassette case  112 . 
   The exciting light source  114 , light guiding means  115 , and photoelectric conversion means  116  are arranged on the side of the stimulable phosphor sheet  120  attached to the front plate  111 , and particularly the exciting light source  114 , light guiding means  115 , and photoelectric conversion means  116  structure the reading means for reading the stimulable emission light from the rear surface side (opposite side to the X-ray irradiation side) of the stimulable phosphor sheet  120 . 
   The cassette accommodation portion  180   a  and image reading portion  180   b  are units which protect each of devices mounted in their inside, and together with it, prevent the image information in which, after the radiographing, the light is irradiated on the stimulable phosphor sheet  120  and which is accumulated and recorded, from being vanished, and it is preferable that they are made of the materials with comparatively high rigidity, so that they surely protect each of devices mounted in their inside. 
   The exciting light source  114  performs the function by which, by irradiating the exciting light on the stimulable phosphor sheet  120 , the stimulable emission light corresponding to the accumulated and recorded image information is emitted. The exciting light source  114  in the present embodiment, while it is reciprocated in the arrowed direction in  FIG. 11   a , can irradiate the exciting light on the stimulable phosphor sheet  120 . 
   The light guiding means  115  functions in such a manner that the stimulable emission light emitted from the stimulable phosphor sheet  120  is guided to the photoelectric conversion means  116 , and is made of a transparent acrylic plate. In this connection, the light guiding means  115  reciprocates in timed relationship with the exciting light source  114 . 
   The photoelectric conversion means  116  detects the stimulable emission light emitted from the stimulable phosphor sheet  120 , and generates the electric signal corresponding to the light amount of the stimulable emission light. In the present embodiment, as the photoelectric conversion means  116 , a photo-multiplier is adopted. 
   The image processing means  117  A/D converts the image information converted into the electric signal by the photoelectric conversion means  116 , and obtains the digital signal. 
   The image output means  118  outputs the digital signal obtained by the image processing means  117  as the X-ray image. As this image output means  118 , other than the device displaying the X-ray image such as CRT or liquid crystal display, the device which hardcopies the X-ray image, such as the inkjet printer, can be listed. 
   After the erasing means  119  reads the image information from the stimulable phosphor sheet  120  by the reading means composed of the exciting light source  114 , light guiding means  115 , and photoelectric conversion means  116 , it emits the radiation energy remaining in the stimulable phosphor sheet  120 , and erases the image information. By this erasing means  119 , the new X-ray radiographing can be conducted onto the stimulable phosphor sheet  120 . 
   In the radiation image reading apparatus  180  structured in this manner, by the X-ray radiographing using the cassette  110 , the image information of the X-ray which passes through the subject  150 , and front plate  111 , and further, grid  113 , and is accumulated and recorded on the stimulable phosphor sheet  120 , can be read. 
   Further, in this manner, on the surface opposite to the surface on which the radiation is irradiated onto the stimulable phosphor sheet  120 , by reading the image information, more accurate image information can be obtained. 
   This is because the difference is generated in the image information accumulated and recorded by the energy difference of the radiation components. The direct component of the image information in the radiation is the radiation having the straight advancing comparatively high energy. As compared with this, the scattering ray generated when the radiation collides with the material, is the radiation having the comparative low energy, and the image information is scattered and disturbed. Furthermore, when the grid  113  is provided, the energy of the scattered ray is more reduced. 
   Because, to accumulate and record the image information on the stimulable phosphor sheet  120 , also means that the energy of the radiation is absorbed in the stimulable phosphor sheet  120 , the high energy straight advancing radiation can reach the rear side of the stimulable phosphor sheet  120 , and the image information can be accumulated and recorded on the rear side. On the one hand, although the low energy scattered radiation can accumulate and record the image information on the front side of the stimulable phosphor sheet  120 , the energy is absorbed before it reaches the rear side, and the component which reaches the rear side is small. Accordingly, because the image information of the rear side is the information which has many direct components of the image information (scattering ray is small), more accurate image information can be obtained. 
   In this connection, in the fourth embodiment, although the structure in which the grid  113  is provided on the front plate  111 , is adopted, the structure in which the front plate  111  itself is formed as the grid  113 , may also be adopted. According to this structure, without even the necessity of the structure in which the grid  113  is provided on the front plate  111 , the same effect can be obtained. 
   (The Fifth Embodiment) 
   The cassette  110   a  according to the present embodiment, as shown in  FIG. 12 , has the rectangular plane shape, and the grid  113  as the front plate is fixed on the cassette case  112   a  as the housing main body. Further, as shown in  FIG. 13 , the cassette  110   a  is provided with the grid  113  as the front plate, stimulable phosphor sheet  120 , protective film  123 , and cassette case  112   a . This cassette  110   a  protects the stimulable phosphor sheet  120  at the time of radiographing or conveying, and further, prevents the image information in which the light is irradiated on the stimulable phosphor sheet  120  after the radiographing, from being vanished. 
   The grid  113  as the front plate is provided with the stimulable phosphor sheet  120 , and attached so as to cover the accommodation portion  112   x  of the cassette case  112   a , and also performs the function as the light shielding plate which, after the radiographing, when the light is irradiated on the stimulable phosphor sheet  120 , prevents the case where the accumulated image information is vanished. In the present embodiment, the grid  113  as the front plate and the cassette case  112   a  are the fixedly provided integrated structure (refer to  FIG. 12 ,  FIG. 13   a  and  FIG. 13   b ). 
   Relating to the X-ray radiographing, because it is the same as the fourth embodiment, the description will be omitted. 
   The cassette case  112   a  is provided with the accommodation portion  112   x  to accommodate the stimulable phosphor sheet  120 , and prevents, at the time of the radiographing or conveying, the stimulable phosphor sheet  120  from being damaged, and together with that, prevents, when the light is irradiated on the stimulable phosphor sheet  120  after the radiographing, the accumulated and recorded image information from being vanished. 
   Further, on the cassette case  112   a , a rotation axis  112   y , and an open and close-able lid portion  112   z  which is attached to the rotation axis  112   y  and rotated around the rotation axis  112   y  as the center, are provided. 
   The lid portion  112   z  is opened in the case where the stimulable phosphor sheet  120  is taken from the cassette case  112   a  when the image information accumulated and recorded on the stimulable phosphor sheet  120  is read, in the radiation image reading apparatus inside. 
   In this connection, in  FIGS. 12 ,  13   a  and  13   b , the rotation axis  112   y  is provided at about the center of the cassette case  112   a , however, when it is a portion where the aperture area from which the stimulable phosphor sheet  120  can be taken from the cassette case  112   a  can be secured, it is not particularly limited, and further, corresponding to a portion at which the rotation axis  112   y  is provided, the dimension of the lid portion  112   z  is changed. 
   In this connection, because the material of the cassette case  112   a  is the same as the cassette case  112 , the description will be omitted. 
   Relating to the grid  113 , because it is the same as the fourth embodiment, the description will be omitted. 
   The protective film  123  having the light transparency is provided on the surface of the stimulable phosphor  122  of the stimulable phosphor sheet  120  (sheet-like supporting body  121 , the stimulable phosphor  122 ), and prevents the deterioration and damage of the stimulable phosphor  122 . In this connection, the sheet-like supporting body  121  and protective film  123  in the fifth embodiment are structured by the material having particularly the flexibility, for example, such as PET. 
   The stimulable phosphor sheet  120  in the present embodiment is attached to the grid  113  as the front plate by a fixing means, not shown, and is accommodated in the accommodation portion  112   x  of the cassette case  112   a  (refer to  FIGS. 13   a  and  13   b ). The thickness of the stimulable phosphor sheet  120  can be appropriately determined corresponding to the accumulating X-ray amount, the kind of the stimulable phosphor, and the height of the accommodation portion  112   x  of the cassette case  112   a.    
   Next, the radiation image reading apparatus using the cassette  110   a  of the fifth embodiment and the method will be described. 
     FIG. 14   a  is a view showing the main portion structure of the radiation image reading apparatus  280  according to the present embodiment, and it is an apparatus to read the image information accumulated and recorded on the stimulable phosphor sheet  120  accommodated in the cassette  110   a.    
   The radiation image reading apparatus  280  is, as shown in  FIG. 14   a , provided with an apparatus housing  280   a , cassette insertion portion  280   b , the exciting light source  114 , light guiding means  115 , photoelectric conversion means  116 , image processing means  117 , image output means  118 , erasing means  119 , a stimulable phosphor sheet take-out means  130 , stimulable phosphor sheet conveying means  131 , and stimulable phosphor sheet accommodation portion  132 . 
   The radiation reading apparatus  280  operates in such a manner that the lid portion  112   z  of the cassette  110   a  which is inserted into the cassette insertion portion  280   b  of the apparatus housing  280   a  is opened, and from the opening section, the image information is read by the reading means (exciting light source  114 , light guiding means  115 , photoelectric conversion means  116 ) which is provided on the conveying path on which the stimulable phosphor sheet  120  taken out by the stimulable phosphor sheet take-out means  130  is conveyed by the stimulable phosphor sheet conveying means  131 . 
   The exciting light source  114 , light guiding means  115 , and photoelectric conversion means  116  are arranged on the rear surface side (opposite side to the X-ray irradiation side) of the stimulable phosphor sheet  120  conveyed by the stimulable phosphor sheet conveying means  131 , and they structure the reading means for reading the stimulable emission light from the rear surface side of the stimulable phosphor sheet  120 . 
   The apparatus housing  280   a  protects each kind of devices mounted in its inside, and together with this, prevents the image information in which the light is irradiated on the stimulable phosphor sheet  120  after the radiographing, and accumulated and recorded, from being vanished, and it is preferable that it is made of the material having the comparatively high rigidity so that each kind of devices mounted in its inside can be surely protected. 
   The aperture of the cassette insertion portion  280   b  is simultaneously opened with the insertion of the cassette  110   a . At the time of the opening, by the structure in which the opening section is closely contact with the cassette  110   a , it is structured so that the light does not enter the inside of the apparatus housing  280   a.    
   Although it is only different from the first embodiment that the exciting light source  114 , light guiding means  115 , and photoelectric conversion means  116  are not moved by the drive mechanism, because other functions are same, the description will be omitted. Further, because the image processing means  117  and image output means  118  are the same as the fourth embodiment, the description will be omitted. 
   The stimulable phosphor sheet take-out means  130  is a means by which the stimulable phosphor sheet  120  is taken from the inside of the cassette  110   a  by, for example, a suction cup, and guided to the stimulable phosphor sheet conveying means  131 . 
   The stimulable phosphor sheet conveying means  131  is a means by which the stimulable phosphor sheet  120  is conveyed by, for example, one pair of the upper and lower guide rollers to the position at which the image information is read by the reading means (the exciting light source  114 , light guiding means  115 , and photoelectric conversion means  116 ). The sheet-like supporting body  121  and protective film  123  of the stimulable phosphor sheet  120  are structured by the material having the flexibility, therefore, at the time of the conveyance by the guide roller, even when it is not only the straight advancing conveying path, but also the arc-like curving conveying path, the stimulable phosphor sheet  120  can be conveyed. 
   Further, in the stimulable phosphor sheet  120  by which the reading of the image information is completed, the radiation energy remaining in the stimulable phosphor sheet  120  is discharged by the erasing means  119 , and the image information is erased. By this erasing means  119 , after the stimulable phosphor sheet  120  becomes the situation in which the new X-ray radiographing can be conducted, it is conveyed to the stimulable phosphor sheet accommodation portion  132 . 
   The stimulable phosphor sheet accommodation portion  132  accommodates the stimulable phosphor sheet  120  in which the reading of the image information is completed. The accommodated stimulable phosphor sheet  120  is taken out by a predetermined method. 
   In the radiation reading apparatus  280  structured in this manner, by the X-ray radiographing using the cassette  110   a , the image information of the X-ray which passes through the subject  150  and grid  113 , and which is accumulated and recorded on the stimulable phosphor sheet  120 , can be read. 
   Further, in the same as in the first embodiment, on the surface opposite to the surface on which the radiation is irradiated on the stimulable phosphor sheet  120 , when the image information is read, more accurate image information can be obtained. 
   Further, a modified example of the radiation image reading apparatus using the cassette  110   a  of the fifth embodiment, will be described. 
     FIG. 15   a  shows the main portion structure of the radiation image reading apparatus  280 ′ according to the present embodiment, and it is an apparatus by which, after the stimulable phosphor sheet  120  accommodated in the cassette  110   a  is taken out, and the image information accumulated and recorded on the stimulable phosphor sheet  120  is read out, the operation to return the stimulable phosphor sheet  120  to the cassette  110   a , is conducted. 
   The radiation image reading apparatus  280 ′ is, as shown in  FIG. 15 , provided with an apparatus housing  280 ′ a , cassette insertion portion  280 ′ b , the exciting light source  114 , light guiding means  115 , photoelectric conversion means  116 , image processing means  117 , image output means  118 , erasing means  119 , stimulable phosphor sheet take-out means  130 , and stimulable phosphor sheet conveying means  131 . 
   In the radiation image reading means  280 ′, as compared with the radiation image reading apparatus  280 , only the conveying path of the stimulable phosphor sheet  120  is different, and because the other functions are same, only the different portion will be described. 
   The stimulable phosphor sheet  120  taken from the inside of the cassette  110   a  by the stimulable phosphor sheet take-out means  130 , is guided by the stimulable phosphor sheet conveying means  131  to the position of the reading means (the exciting light source  114 , light guiding means  115 , and photoelectric conversion means  116 ), and the image information is read out. The sheet-like supporting body  121  and protective film  123  of the stimulable phosphor sheet  120  are structured by the material having the flexibility, therefore, at the time of the conveyance by the guide roller, even when it is not only the straight advancing conveying path, but also the arc-like curving conveying path, the stimulable phosphor sheet  120  can be conveyed. In the stimulable phosphor sheet  120  by which the reading of the image information is completed, the radiation energy remaining in the stimulable phosphor sheet  120  is discharged by the erasing means  119  provided on the conveying path on which it is returned to the cassette  110   a  by the stimulable phosphor sheet conveying means  131 , and the image information is erased. By this erasing means  119 , after the stimulable phosphor sheet  120  becomes the situation in which the new X-ray radiographing can be conducted, it is returned to the inside of the cassette  110   a  by the stimulable phosphor sheet conveying means  131 . 
   Even when the apparatus is the radiation image reading apparatus  280 ′ of such structure, the same effect as the radiation image reading apparatus  280  is obtained. 
   In this connection, in the fifth embodiment, the structure in which the grid  113  as the front plate is provided, is adopted, however, the structure in which the front plate is provided on the outer surface of the grid  113  as a separated body, may also be adopted. According to such a structure, the cassette  110   a  can be reinforced by the front plate, and together with that, the same effect can be obtained. 
   In this connection, the protective film  123  is not necessary when the stimulable phosphor  122  is not deteriorated or damaged, or when the deterioration or damage is not problem, and it may be not provided. 
   (The Sixth Embodiment) 
   The cassette  110   b  according to the present embodiment, as shown in  FIG. 16 , has the rectangular plane shape, and the slide plate  140  is separably jointed with the cassette case  112   b . Further, as shown in  FIGS. 17   a  and  17   b , the cassette  110   b  is provided with the front plate  111   b , grid  113 , stimulable phosphor sheet  120 , slide plate  140 , and cassette case  112   b . This cassette  110   b  protects the stimulable phosphor sheet  120  at the time of radiographing or conveying, and together with this, prevents the image information in which the light is irradiated on the stimulable phosphor sheet  120  after the radiographing and accumulated, from being vanished. 
   The grid  113  is attached to the rear surface of the front plate  111   b . The front plate  111   b  is attached so as to cover the accommodation portion  112   x  of the cassette case  112   b , and when the light is irradiated on the stimulable phosphor sheet  120  after the radiographing, it also performs the function as the light shielding plate to prevent the accumulated image information from being vanished. 
   Relating the X-ray radiographing, because it is the same as the forth embodiment, the description will be omitted. Further, relating to the front surface  111   b , because its material is the same as the front plate  111 , the description will be omitted. 
   In the cassette case  112   b , other than a point that its shape is different from the cassette case  112 , because it is the same, the description will be omitted. Further, because the grid  113  is the same as the fourth embodiment, the description will be omitted. 
   The slide plate  140  is formed of the resins having the light transparency, and to its surface side (the X-ray irradiation side), the stimulable phosphor sheet  120  is attached. In the present invention, it is structured such that, when the a side edge portion  140 ′ of the slide plate  140  is engaged with a guide groove  112 ′ b  corresponding to the thickness of the side edge portion  140 ′, that is, with the inside of the side surface of the cassette case  112 , the slide plate  140  is slid to the cassette case  112   b  (refer to  FIG. 16 ,  FIG. 17   a  and  FIG. 17   b ). 
   Because the stimulable phosphor sheet  120  (sheet-like supporting body  121 , stimulable phosphor  122 ) is the same as the fourth embodiment, the description will be omitted. 
   The stimulable phosphor sheet  120  in the present invention is attached to the slide plate  140  by the fixing means, not shown, and following the slide operation of the slide plate  40 , it is accommodated in or taken from the accommodation portion  112   x  of the cassette case  112   b  (refer to  FIG. 11 ,  FIG. 17   a  and  FIG. 17   b ). In this case, because the grid  113  and the stimulable phosphor sheet  120  are in the condition of close contact with each other, there is a possibility that the friction is generated between the grid  113  and the stimulable phosphor sheet  120  at the time of the slide operation. Therefore, it is preferable that the stimulable phosphor sheet  120  is protected by covering with the protective film (not shown). By the protection, the stimulable phosphor sheet  120  is prevented from the flaws being generated by the friction, and the deterioration of the image information due to the flaws is prevented. 
   The thickness of the stimulable phosphor sheet  120  can be appropriately determined corresponding to the accumulated X-ray amount, the kind of the stimulable phosphor, and the height of the accommodation portion  112   x  of the cassette case  112   b.    
   Next, the radiation image reading apparatus using the cassette  110   b  of the sixth embodiment, and the method will be described. 
     FIG. 18   a  is a view showing the main portion structure of the radiation image reading apparatus  380  according to the present embodiment, and it is an apparatus to read the image information accumulated and recorded on the stimulable phosphor sheet  120  accommodated in the cassette  110   b.    
   The radiation image reading apparatus  380  is, as shown in  FIG. 18   a , provided with a cassette accommodation portion  380   a , the exciting light source  114 , light guiding means  115 , photoelectric conversion means  116 , image processing means  117 , image output means  118 , and erasing means  119 . 
   The radiation reading apparatus  380  operates in such a manner that, from the cassette  110   b  accommodated in the cassette accommodation portion  380   a , the slide plate  140  is conveyed to the image reading section  380   b  by the conveying means, not shown, and next, after the image information is read from the stimulable phosphor sheet  120  provided on the slide plate  140 , the slide plate  140  is returned to the cassette case  112   b.    
   The exciting light source  114 , light guiding means  115 , and photoelectric conversion means  116  are arranged on the slide plate  140  side, and they structure the reading means for reading the stimulable emission light from the rear surface side (opposite side to the X-ray irradiation side) of the stimulable phosphor sheet  120 . 
   In the radiation image reading apparatus  380 , other than a point that the slide plate  140  is conveyed from the cassette  110   b  to the image reading section  380   b  by the conveying means, not shown, and the image information is read, because it is the same as the fourth embodiment (radiation reading apparatus  180 ), the description will be omitted. 
   According to the radiation image reading apparatus  380  structured as described above, by the X-ray radiographing using the cassette  110   b , the image information of the X-ray which passes through the subject  150  and front plate  111   b , and further, grid  113 , and which is accumulated and recorded on the stimulable phosphor sheet  120 , can be read. Particularly, because the slide plate  140  has the light penetrability, the image information accumulated and recorded on the stimulable phosphor sheet  120  can be read through the slide plate  140 . 
   Further, in the same as the fourth embodiment, on the surface opposite to the surface on which the radiation is irradiated onto the stimulable phosphor sheet  120 , by reading the image information, more accurate image information can be obtained. 
   Further, the slide plate  140  functions also as the protective plate to protect the stimulable phosphor  122  of the stimulable phosphor sheet  120 . 
   As described above, in the cassette, when the radiation image accumulated and recorded on the stimulable phosphor sheet  120  provided in contact with the grid  113  is read from the stimulable phosphor sheet  120 , on the surface opposite to the surface on which the radiation is irradiated onto the stimulable phosphor sheet  120 , when the image information is read, more accurate image information can be obtained. 
   In this connection, in the above embodiments, it is defined that the front plates  111  and  111   b  are made of the carbon fiber reinforced resins, however, the present invention is not limited to this, but it may also be made of the grid, and further, it may also be structured such that, on the front surface of the grid  113 , the front plate is provided. 
   Further, it is defined that the front plate  111  is detachable by the slide motion, however, the present invention is not limited to this, but any detaching mechanism by using the holding means or engaging means may also be used. Further, the structure of the radiation image reading apparatus is also at will, and other than that, it is of course that also the specific detailed structure is appropriately changeable. 
   (The Seventh Embodiment) 
   Instead of the grid in the first to the sixth embodiments, an embodiment using a metallic foil (used as a metallic layer) will be described below. 
     FIG. 19  is an example in which the metallic foil is used instead of the grid in  FIG. 2 , and in the moisture-proof protective film  20  arranged on the supporting plate  12  side, a metallic foil  21  is provided. This metallic foil  21  is a metallic layer which performs the function to remove the X-ray (scattered ray) of the low energy scatted when the X-ray successively passes through the subject  140 , front plate  11   a  of the housing  11  and supporting plate  12 . 
   In order to perform the above-described function, the metallic foil  21  is structured by a metal more than the atomic number  20 , or an alloy more than the effective atomic number  20 . For example, it can be structured by at least one kind in the metals more than the atomic number  20  such as Cu, Ni, Fe, Pb, Zn, W, Mo, Au, Ag, Ba, Ta, Cd, Ti, Zr, V, Nb, Cr, Co and Sn, or an alloy of these metals. Because these metals and alloys absorb the low energy X-ray, the scattered ray can be effectively absorbed and removed. 
   Herein, the “effective atomic number” means the atomic number when the atomic number of each metal constituting the alloys is averaged based on the mole ratio. For example, in the case of an alloy structured in the condition that the mole ratio of Co (the atomic number  27 ) and Cu (the atomic number  29 ) is 1:1, the effective atomic number is  28 . In the present embodiment, as the metallic foil  21 , the copper foil structured by Cu (the atomic number is  29 ) is adopted. 
   It is commonly said that the average radiation transmission factor of the local portion  21   a  of the area 1 mm 2  extracted from the surface of the metallic foil  21  (refer to  FIG. 20(   a )), is ½ times to 2 times of the average radiation transmission factor in the whole surface area. That is, when the average radiation transmission factor Tn for each of local portions (extraction number n) a plurality of which are arbitrarily extracted, is plotted in a graph of  FIG. 20(   b ) in which the vertical axis expresses the radiation transmission factor and the horizontal axis expresses the extraction number n, each plotted point distributes in the area R (0.5 Tm≦T≦2 Tm, Tm: the average radiation transmission factor in the whole surface area of the metallic foil  21 ). This shows that the radiation transmission factor of the metallic foil  21  is comparatively uniform over the whole surface. 
   The thickness of the metallic foil  21  is defined that it is not lower than 5 μm and not larger than 200 μm. When the thickness is not larger than 5 μm, because the scattered ray removing function is not sufficiently performed, it is not preferable. Further, when the thickness is not lower than 200 μm, because the scattered ray by the metallic foil  21  affects the bad influence on the X-ray image, it is not preferable. In the present embodiment, the thickness of the metallic foil  21  is set to 12 μm. 
   The metallic foil  21  can be produced by an electrolyte method (refer to  FIG. 21 ) by which the metal electrically adhered from the electrolyte  50  onto the rotation drum  60  is peeled and wound, or by rolling method by which the metallic line is rolled by a multistage mill. In the present embodiment, the electrolyte method is adopted, and the metallic foil  21  produced by the electrolyte method, as its cross section is shown in  FIG. 22 , has the pillar structure  21   b . Accordingly, the X-ray parallel to the pillar direction (including the image information) can be effectively transmitted, and the scattered ray not parallel to the pillar direction (not including the image information) can be effectively cut off. 
   In the X-ray image reading apparatus according to the present embodiment, because, between the supporting plate  12  and the stimulable phosphor sheet  19 , the metallic foil  21  structured by Cu is fixedly adhered, the X-ray of the low energy (scattering ray) scattered when it passes through the subject  40 , can be effectively shielded. Further, because the thickness of this metallic foil  21  is set to 12 μm, the scattered ray due to this metallic foil  21  does not affect the bad influence on the X-ray image. Accordingly, the image quality of the X-ray image can be greatly increased. 
   Further, because the X-ray image reading apparatus according to the present embodiment adopts the metallic foil  21  having the pillar structure produced by the electrolyte method, the X-ray parallel to the pillar direction (including the image information) can be effectively transmitted, and the scattered ray not parallel to the pillar direction (not including the image information) can be effectively cut off. 
   Further, because the X-ray image reading apparatus according to the present embodiment adopts the carbon fiber reinforced resin as the material of the front plate  11   a  of the housing  11  and supporting plate  12 , the transmission of the X-ray is not hindered, and the lowering of the image quality of the X-ray image can be prevented. 
     FIG. 23  shows an example in which the metallic foil is used instead of the grid in  FIG. 5 , and to the rear surface of the front plate  11   a  of the housing  11  (that is, the surface of the opposite side to the side onto which the X-ray is irradiated), the metallic foil  21  is adhered through the double-side adhesive tape  22 . It is preferable that the double-side adhesive tape  22  is structured of polyester resin with the high X-ray transmission factor or polypropylene. 
   In this connection, in order to prevent the metallic foil  21  from being stained when the metallic foil  21  is exposed in the air for long period of time, as shown in  FIG. 24 , it is preferable that the synthetic resin film  23  is laminated on the other surface of the metallic foil  21  (the surface of the opposite side to the double-side adhesive tape  22 ). As the synthetic resin constituting this film  23 , polyester resin such as polyethylene telephthalate, or polyethylene naphthalate which have the excellent moisture-proof property and high X-ray transmission factor, or polypropylene, can be listed. 
   The kind or thickness of the film  23  can be appropriately set by considering the kind or thickness of the metallic foil  21 . For example, as described above, to the metallic foil  21  formed of Cu of 12 μm thickness, the polyethylene telephthalate film  23  of about 20 μm thickness can be adopted. 
     FIG. 25  is a view showing an example using the metallic foil instead of the grid in  FIG. 7 , and to the rear surface of the supporting plate  12  (the surface of the opposite side to the side on which the X-ray is irradiated), the metallic foil  21  is adhered through the double-side adhesive tape  22 , and at the time of the X-ray radiographing, the X-ray of the low energy scattered when the X-ray passes through the subject can be effectively removed. In this connection, in the same as the above-described embodiment, in order to prevent the metallic foil  21  from being stained when the metallic foil  21  is exposed in the air for long period of time, on the other surface of the metallic foil  21  (the surface opposite to the double-side adhesive tape), the synthetic resin film can also be laminated. 
     FIG. 26  shows an example in which the metallic foil is used instead of the grid in the cassette in  FIG. 16 . In  FIG. 27(   a ), the metallic foil  113  is adhered to the rear surface of the front plate  111   b  of the housing  111  (that is, the surface of the opposite side to the side on which the X-ray is irradiated) through the double-side adhesive tape  114 , and is a metallic layer which performs the function to remove the X-ray (scattering ray) of the low energy scattered when the X-ray passes through the subject  130  and the front plate  111   b . It is preferable that the double-side adhesive tape  114  is structured of polyester resin with the high X-ray transmission factor, or polypropylene. 
   The stimulable phosphor sheet  120  in the present invention is temporarily fixed to the slide plate  112  by the fixing means, not shown, and following the slide operation of the slide plate  112 , it is accommodated in the accommodation portion  111   a  of the housing  111  (refer to  FIG. 27(   a )). The thickness of the stimulable phosphor sheet  120  can be appropriately determined corresponding to the accumulated X-ray amount, the kind of the stimulable phosphor, and the height of the accommodation portion  111   a  of the housing  111 . In this connection, in the present embodiment, as the fixing means, the double-side adhesive tape in which the lead foil to absorb the X-ray, exists, is adopted. 
   Further, in the present embodiment, the stimulable phosphor sheet  120  is arranged in the condition that it is separated by about 4 mm from the metallic foil  113  (refer to  FIG. 27(   b )). In this manner, by separating the stimulable phosphor sheet  120  from the metallic foil  113 , when the stimulable phosphor sheet  120  is slid integrally with the slide plate  112 , it can be prevented that the metallic foil  113  is brought into contact with the stimulable phosphor  122 , and the physical damage and the optical deterioration of the stimulable phosphor  122  can be beforehand prevented. 
   In the cassette  110  according to the present embodiment, because, between the front plate  111   b  of the housing  111  and the stimulable phosphor sheet  120 , because the metallic foil  113  structured by Cu is fixedly adhered, the X-ray of the low energy (scattering ray) scattered when it passes through the subject  130 , can be effectively removed. Further, because the thickness of this metallic foil  113  is set to 12 μm, the scattering ray due to this metallic foil  113  does not affect the bad influence on the X-ray image. Accordingly, the image quality of the X-ray image can be greatly increased. 
   Further, because the cassette  110  according to the present embodiment adopts the metallic foil  113  having the pillar structure produced by the electrolyte method, the X-ray parallel to the pillar direction (including the image information) can be effectively transmitted, and the scattered ray not parallel to the pillar direction (not including the image information) can be effectively cut off. 
   Further, because the cassette  110  according to the present embodiment adopts the carbon fiber reinforced resin as the material of the housing  111 , the transmission of the X-ray is not hindered, and by the excellent rigidity, the stimulable phosphor sheet  120  can be surely protected. 
   In this connection, in order to prevent the metallic foil  113  from being stained when the metallic foil  113  is exposed in the air for long period of time, as shown in  FIG. 28 , it is preferable that the synthetic resin film  115  is laminated on the other surface of the metallic foil  113  (the surface of the opposite side to the double-side adhesive tape  122 ). As the synthetic resin constituting this film  115 , polyester resin such as polyethylene telephthalate, or polyethylene naphthalate which have the excellent moisture proof property and high X-ray transmission factor, or polypropylene, can be listed. 
   The kind or thickness of the film  115  can be appropriately set by considering the kind or thickness of the metallic foil  113 . For example, as described above, to the metallic foil  113  formed of Cu of 12 μm thickness, the polyethylene telephthalate film  115  of about 20 μm thickness can be adopted. In this connection, as shown in  FIG. 28(   b ), also in this case, the stimulable phosphor sheet  120  is arranged in the condition that it is about 3 mm separated from the metallic foil  113 . 
   In this connection, in the embodiments described above, as the means by which the metallic foil  113  is fixedly adhered to the rear surface of the front plate  111   b  of the housing  111 , the double-side adhesive tape  114  is adopted, however, the fixing means is not limited to this, for example, the metallic foil  113  may be adhered to the rear surface of the front plate  111   b  of the housing  111  through the adhesive agent. Also the adhesive agent in this case, it is preferable that it is structured of polyester resin with the high X-ray transmission factor. 
   (The Eighth Embodiment) 
   Next, an embodiment in which the present invention is applied to the X-ray detector having the semiconductor sensor, will be described. 
   The X-ray image radiographing apparatus  210  according to the present embodiment, is provided, as shown in  FIG. 29 , with the housing  211 , X-ray detector  220 , image processing means  230 , and image display means  240 . The housing  211  mounts the X-ray detector  220  or each kind of the other devices in its inside, and is fixed at a predetermined position. 
   The X-ray radiographing is conducted by detecting the X-ray which is irradiated from the X-ray source  250  and which passes through the subject  260  and the front plate  211   a  of the housing  211 , by the X-ray detector  220  (refer to  FIG. 30 ), therefore, the front plate  211   a  of the housing  211  is produced by the material with the high X-ray transmission factor. In this connection, when the thickness of the front plate  211   a  is about 0.3–5 mm, because the penetrability of the X-ray is being secured and the maintaining of the strength can be intended, it is preferable. Further, it is preferable that the housing  211  is produced by the material with the comparatively high rigidity so that each kind of devices mounted in its inside can be surely protected. 
   On the rear surface of the front plate  211   a  of the housing  211  (that is, the surface of the opposite side to the side on which the X-ray is irradiated), the metallic foil  212  is adhered through the double-side adhesive tape  213  (refer to  FIG. 30 ). This metallic foil  212  is a metallic layer performing the function to remove the low energy X-ray (scattering ray) scattered when the X-ray passes through the subject  260  and the front plate  211   a . It is preferable that the double-side adhesive tape  213  is structured of polyester resin which has the high X-ray transmission factor, or polypropylene. 
   In  FIG. 30 , the X-ray detector  220  is composed of the light emitting means  221 , photoelectric conversion means  222 , and supporting plate  223 , and functions so that the irradiated X-ray is converted into the electric signal (image signal). The electric signal (image signal) converted by this X-ray detector  220  is sent to the image processing means  230 , which will he described later, and displayed on the image display means  240 . The X-ray detector  220  is fixed in the housing  211  by the fixing means, not shown. 
   The light emitting means  221  functions so that it emits the light corresponding to the intensity of the irradiated X-ray, and in the present embodiment, a scintillator is adopted. As the scintillator, the conventionally used one such as Gd 2 O 2 :Tb, fluorescent substance such as CaWO 4 , scintillation fiber structured by doping the fluorescent substance in the fiber plate, CsI:Na, or CsI:Tl, can be used without limitation. 
   The light conversion means  222  generates the electric signal of the amount corresponding to the intensity of the light of the light emitting means  221 , which is (light-emitted by the irradiation of the X-ray). The electric signal generated by the photoelectric conversion means  222  is sent to the image processing means  230  which will be described later, and displayed on the image display means  240 . The supporting plate  223  is used for forming the photoelectric conversion means  222  on its upper surface, and in the present embodiment, the glass base plate is adopted. 
   As the photoelectric conversion means  222 , the conventionally used one can be used without limitation. For example, a means or the like in which the thin film transistor (TFT) which is the switching element is formed on the supporting plate  223 , and the PIN photodiode which is photoelectric conversion element is formed in the manner to connect to the TFT, (refer to Japanese Tokkai No. 2000-114530), can be listed. 
   The image processing means  230  is a means by which the electric signal transferred from the X-ray detector  220  is A/D converted and the digital signal is obtained. As the image output means  240 , other than a device to display the X-ray image such as the CRT or liquid crystal display, a device to produce the hard-copy of the X-ray image such as the inkjet printer, can be listed. 
   In the X-ray image radiographing apparatus  210  according to the present embodiment, because, between the front plate  211   a  of the housing  211  and the X-ray detector  220 , the metallic foil  212  structured by Cu is fixedly adhered, the X-ray of the low energy (scattering ray) scattered when it passes through the subject  260 , can be effectively shielded in the condition that the uniformity is excellent. Further, because the thickness of this metallic foil  212  is set to 12 μm, the scattering ray due to this metallic foil  212  does not affect the bad influence on the X-ray image. Accordingly, the image quality of the X-ray image can be greatly increased. 
   In this connection, in order to prevent the metallic foil  212  from being stained when the metallic foil  212  is exposed in the air for long period of time, as shown in  FIG. 31 , it is preferable that the synthetic resin film  214  is laminated on the other surface of the metallic foil  212  (the surface of the opposite side to the double-side adhesive tape  213 ). As the synthetic resin constituting this film  214 , polyester resin such as polyethylene telephthalate, or polyethylene naphthalate which have the excellent moisture proof property and high X-ray transmission factor, or polypropylene, can be listed. 
   In this connection, in the embodiments described above, as the means by which the metallic foil  212  is fixedly adhered to the rear surface of the front plate  211   a  of the housing  211 , the double-side adhesive tape  213  is adopted, however, the fixing means is not limited to this, for example, the metallic foil  212  may be adhered to the rear surface of the front plate  211   a  of the housing  211  through the adhesive agent. Also the adhesive agent in this case, it is preferable that it is structured of polyester resin with the high X-ray transmission factor. 
   Further, in the embodiment described above, the X-ray detector provided with the light emitting means is shown, however, as shown in  FIG. 32 , an X-ray detector  220 ′ provided with the conversion means for directly converting the irradiated X-ray to the electric charge may also be adopted. This X-ray detector  220 ′ is provided with a conversion means  224  by which the electric charge corresponding to the intensity of the irradiated X-ray is generated in the light conducting layer, and the generated electric charge is accumulated in a plurality of capacitors arranged plane-like, and the electric charge accumulated in the conversion means  224  is read out, and the radiation image can be obtained. 
   (The Ninth Embodiment) 
   Next, an example in which the present invention is applied to the X-ray image radiographing-use electronic cassette (electronic cassette)  310  housing the X-ray detector  320  for detecting the X-ray, will be described. 
   The electronic cassette  310  according to the present embodiment shows the rectangular planar shape as shown in  FIG. 33 , and its handle  350  is held by the hand, and appropriately carried to a predetermined position in the hospital and can be used. This electronic cassette  310  is, as shown in  FIG. 34 , provided with a housing  311 , metallic foil  312 , x-ray detector  320 , image information storing means  330  and battery  340 . 
   The housing  311  is one to accommodate parts such as the x-ray detector  320 , image information storing means  330  and battery  340 , in its inside, and performs the function to prevent these accommodated parts from being damaged at the time of radiographing or conveying. The electronic cassette  310  according to the present embodiment is carried to the necessary position in the hospital, however, when assuming that a part of the body of the patient which is the subject  360  is placed on its upper portion, it is preferable that the housing  311  is produced by the material with the comparatively high rigidity. 
   Further, the X-ray radiographing is conducted by detecting the X-ray which passes through the subject  360  and the front surface plate  311   a  of the housing  311 , by the X-ray detector  320  (refer to  FIG. 34 ). Therefore, the front plate  311   a  of the housing  311  is produced with the material having the high X-ray transmission factor. When the thickness of this front plate  311   a  is about 0.3–5 mm, because, while the penetrability of the X-ray is secured, the strength can be maintained, it is preferable. 
   The metallic foil  312  is adhered through the double-side adhesive tape  313  to the rear surface of the front plate  311   a  of the housing  311  (that is, the surface of the opposite side to the side on which the X-ray is irradiated), and is the metallic layer to perform the function to shield the low energy X-ray (scattering ray) scattered when the X-ray passes through the subject  360  and the front plate  311   a . It is preferable that the double-side adhesive tape  313  is structured of polyester resin which has the high X-ray transmission factor, or polypropylene. 
   The X-ray detector  320  has the plane type structure structured by the light emitting means  321 , photoelectric conversion means  322  and supporting plate  323 , and functions so that the irradiated X-ray is converted into the electric signal (image signal). The converted electric signal (image signal) is sent to the outside image processing means connected to the electronic cassette  310 , and displayed on the predetermined image display means. 
   The light emitting means  321  functions so that it emits the light corresponding to the intensity of the irradiated X-ray, and in the present embodiment, the scintillator is adopted. As the scintillator, the conventionally used one such as Gd 2 O 2 :Tb, fluorescent substance such as CaWO 4 , scintillation fiber structured by doping the fluorescent substance in the fiber plate, CsI:Na, or CsI:Tl, can be used without limitation. 
   The light conversion means  322  generates the electric signal of the amount corresponding to the intensity of the light of the light emitting means  321 , which is (light-emitted by the irradiation of the X-ray). The electric signal generated by the photoelectric conversion means  322  is sent to the outside image processing means connected to the electronic cassette  310 , and displayed on a predetermined image display means. The supporting plate  323  is used for forming the photoelectric conversion means  322  on its upper surface, and in the present embodiment, the glass base plate is adopted. 
   As the photoelectric conversion means  322 , the conventionally used one can be used without limitation. For example, a means or the like in which the thin film transistor (TFT) which is the switching element is formed on the supporting plate  323 , and the PIN photodiode which is photoelectric conversion element is formed in the manner to connect to the TFT, (refer to Japanese Tokkai No. 2000-114530), can be listed. 
   The image information storing means  330  performs the function to temporarily store the electric signal (image signal) generated by the X-ray detector  320 . When the image information storing means  330  is provided in the electronic cassette  310 , a trouble in which the electric signal (image signal) obtained by the X-ray radiographing is outputted each time to the outside apparatus, can be omitted. Accordingly, while the arranged position of the electronic cassette  310  is changed, the X-ray radiographing can be continuously conducted in a plurality of times. 
   As the image information storing means  330 , the conventionally used one such as RAM (Random Access Memory), magnetic recording medium, or optical recording medium, can be used without limitation. In this connection, in the electronic cassette  310 , a CPU, not shown, is provided, and by the control of this CPU, the electric signal (image signal) stored in the image information storing means  330  is transferred to the outside image processing means through the connector  370 . 
   The battery  340  is a unit for supplying the electricity to drive each kind of devices in the electric cassette  310 . While this battery  340  is electrically charged, it is not necessary that the electricity is supplied from the outside to the electronic cassette  310 , and the electronic cassette  310  can be used by properly being carried. 
   In the cassette  310  according to the present embodiment, because, between the front plate  311   b  of the housing  311  and the X-ray detector  320 , because the metallic foil  312  structured by Cu is fixedly adhered, the X-ray of the low energy (scattered ray) scattered when it passes through the subject  360 , can be effectively removed in the condition of the excellent uniformity. Further, because the thickness of this metallic foil  312  is set to 12 μm, the scattered ray due to this metallic foil  312  does not affect the bad influence on the X-ray image. Accordingly, the image quality of the X-ray image can be greatly increased. 
   In this connection, in order to prevent the metallic foil  312  from being stained when the metallic foil  312  is exposed in the air for long period of time, as shown in  FIG. 35 , it is preferable that the synthetic resin film  314  is laminated on the other surface of the metallic foil  312  (the surface of the opposite side to the double-side adhesive tape  313 ). As the synthetic resin constituting this film  314 , polyester resin such as polyethylene telephthalate, or polyethylene naphthalate which have the excellent moisture proof property and high X-ray transmission factor, or polypropylene, can be listed. 
   Further, in the embodiment described above, the X-ray detector provided with the light emission means is shown, however, as shown in  FIG. 36 , the X-ray detector  320 ′ provided with the conversion means for converting the irradiated X-ray directly to the electric charge can be adopted. The X-ray detector  320 ′ is provided with the conversion means  324  by which the electric charge corresponding to the intensity of the irradiated X-ray is generated in the light conducting layer, and the generated electric charge is accumulated in a plane-likely arranged plurality of capacitors, and the electric charge accumulated in the conversion means  324  is read out, and the radiation image can be obtained. 
   According to the present invention, by the grid to remove the scattered low energy radiation (scattered ray) generated at the time of the radiation radiographing, the image information according to the scattered ray can be prevented from being accumulated and recorded on the stimulable phosphor sheet. Particularly, when the grid is made as the supporting plate, because the supporting plate becomes unnecessary, and the scattered ray generated in the supporting plate is reduced, the influence of the scattered ray can be more reduced. Further, at the time of the radiation radiographing, because the grid is in contact with the stimulable phosphor sheet, in the stage in which the scattering of the scattered ray generated in the grid itself is smaller, the image information based on the radiation can be accumulated and recorded on the stimulable phosphor sheet, and by reading the accumulated and recorded image information, more accurate image information can be obtained. 
   According to the present invention, the low energy radiation (scattering ray) scattered when it passes through the subject, can be effectively shielded, and the image quality of the radiation image can be greatly increased.