JP4517945B2 - Radiation image conversion panel manufacturing method and radiation image conversion panel - Google Patents

Description

  The present invention relates to a method for manufacturing a radiation image conversion panel and a radiation image conversion panel, and more particularly to a method for manufacturing a radiation image conversion panel formed by vapor deposition and a radiation image conversion panel.

  In the medical field, radiographic images such as X-rays are often used for diagnosing diseases. Conventionally, a radiation image is formed by irradiating a phosphor layer (fluorescent screen) with radiation that has passed through a subject, thereby generating visible light and taking this visible light in the same way as when taking a normal photograph. In general, a method using a so-called radiograph in which a film using a silver salt is irradiated and developed after forming a latent image.

  However, in recent years, as a method for forming a radiographic image without using a film coated with silver salt, the stimulable phosphor of the stimulable phosphor plate absorbs the radiation that has passed through the subject, and then this stimulation is performed. For example, when excited phosphor is excited by light or thermal energy, radiation energy absorbed and stored in this stimulable phosphor is emitted as stimulated light, and this stimulated light is detected and imaged. A method has been proposed.

  Here, the stimulable phosphor plate is one type of radiation image conversion panel, and the radiation image conversion panel represented by such a stimulable phosphor plate is as sensitive to radiation as possible, and image quality is as high as possible. It is desired to provide an image having good (sharpness, graininess, etc.), and researches for improving the sensitivity and improving the image quality of the radiation image conversion panel have been conducted.

  The superiority or inferiority of the radiation image conversion method using the radiation image conversion panel depends greatly on the stimulable light emission luminance of the panel and the light emission uniformity of the panel, and in particular, the characteristics of the stimulable phosphor used for these characteristics. It is known that the characteristics are largely dominated.

  By the way, such a radiation image conversion panel can be formed by a vapor deposition method depending on a phosphor material to be used, and Patent Document 1 discloses a method for producing a stimulable phosphor plate by a vapor deposition method. . In the vapor deposition method, a phosphor plate having a structure in which crystals are arranged in an orderly manner such as columnar crystals can be formed on the surface of the support by evaporating and vaporizing the phosphor material and growing crystals attached to the support. .

  However, in this method, crystals that grow on the support from the point of attachment of the foreign matter due to bumps generated when the raw material is vaporized or foreign matter such as scratches or dust slightly attached on the support are formed. Abnormal growth may occur, and at the location where the crystal on the support has grown abnormally, the abnormality extends to the surface of the phosphor plate, causing a protrusion in which the crystal partially protrudes compared to the surrounding area. There was a case.

  In the phosphor plate on which the protrusions due to such abnormal growth occur on the phosphor surface, the excitation light irradiated to the radiation image conversion panel causes scattering and refraction in unnecessary directions by the protrusions. Similarly, the stimulated light generated by excitation causes scattering and refraction different from those of the normal part, thereby generating image noise such as speckles and causing deterioration of image quality.

On the other hand, Patent Document 2 discloses a method for manufacturing a radiation image conversion panel including a process of polishing the entire surface of a phosphor plate formed by a vapor deposition method so as to have a uniform layer thickness with an abrasive. It has been attempted to make the film thickness of the phosphor plate having a non-uniform film thickness distribution uniform.
JP 2003-279696 A JP-T-2004-537646

  However, in the process of polishing the entire surface of the phosphor plate with a polishing agent so as to have a uniform layer thickness, the surface of the phosphor plate is attached with polishing agent or dust / polishing waste generated in the polishing process, or crystals. If the abrasive enters the gap, there is a possibility that another abnormality such as an abnormality in the light emission characteristic or an image failure may be newly generated. Further, there is a risk that the material is wasted including the use of an abrasive and the cost may be increased.

  An object of the present invention is to provide a method for manufacturing a radiation image conversion panel capable of providing a high-quality image while preventing generation of image noise.

In order to solve the above problems, the invention according to claim 1
In the method of manufacturing a radiation image conversion panel that forms a phosphor plate composed of a support and a phosphor layer formed on the support through a vapor deposition step,
After the vapor deposition step, based on the luminance difference from the phosphor plate, a determination step of determining the presence and the amount of protrusion on the phosphor layer surface, and
After the determination step, the phosphor layer surface is partially removed in the layer thickness direction of the phosphor layer by laser ablation, or the phosphor plate is interposed between a pair of heating rollers or pressure rollers by calendering to pass, characterized by having a a flattening step of flattening only the protruding portion present in the phosphor layer on the surface in accordance with the determination result in said determination step.

According to the first aspect of the present invention, since there is a flattening step for flattening only the protrusions existing on the surface of the phosphor layer, only the protrusions on the phosphor surface are flattened, so Anomalous scattering and anomalous refraction can be reduced.
Then, when this planarization step is a step of partially removing the phosphor layer surface in the layer thickness direction of the phosphor layer by a laser ablation method, the protrusions on the phosphor layer surface are instantaneously and locally removed. The temperature is raised to cause thermal decomposition or gasification, and a certain amount is partially removed in the phosphor layer thickness direction to flatten the phosphor layer surface. Further, when the flattening step is performed by calendar processing, the projecting portion on the phosphor plate is crushed by passing the phosphor plate between a pair of heating or pressure rollers, and the phosphor layer 3 Can be planarized.
Furthermore, the present invention has a determination process for determining the presence or absence of protrusions, and sequentially performs a vapor deposition process, a determination process, and a planarization process. Originally, a flattening step can be performed on the protruding portion, and the flattening step can be reliably performed on the protruding portion.

  Invention of Claim 2 is a manufacturing method of the radiation image conversion panel of Claim 1, Comprising: The said fluorescent substance plate has a protective layer provided so that the said fluorescent substance layer surface might be covered, It is characterized by the above-mentioned. To do.

  According to the invention described in claim 2, since the phosphor plate has a protective layer covering the phosphor layer surface, the phosphor layer surface is physically damaged such as scratches from the outside and chemical damage such as moisture absorption. Can be protected from. Further, it is possible to reduce the shape deformation given to the protective layer by the protrusions and the accompanying abnormal scattering and abnormal refraction generated in the protective layer and at the boundary surface between the protective layer and the phosphor layer.

The invention described in claim 3 is the method for manufacturing a radiation image conversion panel according to claim 1 or 2 , wherein the determination step and the flattening step are repeated.

According to the invention described in claim 3 , since the determination step and the flattening step are repeatedly performed, the determination step can be performed again after the flattening step, and the result in the determination step and the result in the flattening step are obtained. It is possible to feed back, and the protrusions can be flattened more finely according to the state of the surface of the phosphor plate.

Invention of Claim 4 is a manufacturing method of the radiographic image conversion panel as described in any one of Claims 1-3 , Comprising: The said fluorescent substance layer is the fluorescent substance formed by a vapor deposition method It is characterized by comprising.

According to the fourth aspect of the present invention, the same action as that of the first to third aspects of the invention can be obtained in applying the gas layer deposition method as the method for producing the phosphor layer.

Invention of Claim 5 is a manufacturing method of the radiographic image conversion panel as described in any one of Claims 1-4 , Comprising: The said fluorescent substance is a stimulable fluorescent substance, It is characterized by the above-mentioned. To do.

According to the invention described in claim 5, when the stimulable phosphor is applied as the material of the phosphor, the same effect as that of the invention of claims 1 to 4 can be obtained.

Invention of Claim 6 is a manufacturing method of the radiographic image conversion panel of Claim 5 , Comprising: The said stimulable fluorescent substance contains the compound of the composition represented by following General formula (1). It is characterized by that.
M1X · aM2X ′ ₂ · bM3X ″ ₃ : eA (1)
[Wherein M1 is at least one alkali metal selected from Li, Na, K, Rb and Cs, and M2 is selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd, and Ni. M3 is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga and In. At least one trivalent metal selected from the group consisting of: X, X ′ and X ″ are at least one halogen selected from the group consisting of F, Cl, Br and I, and A is Eu, Tb, At least one metal selected from the group consisting of In, Ga, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, TI, Na, Ag, Cu, and Mg. Yes, a, b, Each represents a number between 0 ≦ a <0.5,0 ≦ b <0.5,0 <e ≦ 0.2.]

According to the invention described in claim 6 , a stimulable phosphor that contains a compound satisfying the general formula (1) can be applied, and the same effect as that of the invention of claim 5 can be obtained. Can do.

The invention described in claim 7, wherein the stimulable phosphor to a method for producing a radiation image conversion panel according to claim 5 or claim 6, compound composition represented by the following general formula (2) It is characterized by containing.
CsX: eA (2)
[Wherein X is Cl, Br or I, A is Eu, Sm, In, TI, Ga or Ce, and e is a numerical value in the range of 0.0000001 ≦ e ≦ 0.01. ]

According to invention of Claim 7 , what contains the compound which satisfy | fills the said General formula (2) can be applied as a stimulable fluorescent substance, It is the same as that of the invention of Claim 5 or Claim 6. The effect can be obtained.

The invention according to claim 8 is a radiation image conversion panel comprising a phosphor plate composed of a support and a phosphor layer formed on the support through a vapor deposition step.
The phosphor plate has the phosphor according to a result determined by a determination step of determining the presence / absence of a protrusion on the surface of the phosphor layer and a protrusion amount based on a difference in light emission luminance from the phosphor plate. Flattening by partially removing the surface of the layer in the thickness direction of the phosphor layer by a laser ablation method, or by calendering that passes the phosphor plate between a pair of heating rollers or pressure rollers Only the projecting portion existing on the surface of the phosphor layer is planarized by the planarizing step.

According to the invention described in claim 8 , the radiation including the phosphor plate in which only the protrusion on the surface of the phosphor is flattened through the flattening step of flattening only the protrusion on the surface of the phosphor layer. Since it can be set as an image conversion panel, abnormal scattering and abnormal refraction of excitation light and fluorescence can be reduced in the panel.

According to the first aspect of the present invention, since the flattening step can be reliably performed on the protrusion, abnormal scattering and abnormal refraction of excitation light and fluorescence can be reduced, and image noise can be reduced. High-quality images can be obtained.

  According to invention of Claim 2, while protecting from the physical and chemical damage to the fluorescent substance layer surface, the shape deformation | transformation given to the protective layer by a processus | protrusion, and the accompanying extraordinary scattering and anomalous refraction are reduced. Therefore, it is possible to reduce image noise and obtain a high-quality image.

According to the invention described in claim 3 , since the protrusion can be flattened more finely according to the state of the surface of the phosphor plate, it is possible to further reduce the abnormal scattering and abnormal refraction of excitation light and fluorescence. In addition, image noise can be further reduced to obtain a high-quality image.

According to the fourth aspect of the present invention, the same effects as those of the first to third aspects of the present invention can be obtained when the gas layer deposition method is applied as a method for producing the phosphor layer.

According to the invention described in claim 5, when the stimulable phosphor is applied as the phosphor material, the same effects as those of the inventions of claims 1 to 4 can be obtained.

According to the invention described in claim 6 , since a stimulable phosphor containing a compound satisfying the general formula (1) can be applied, a high-luminance and high-quality phosphor plate is produced. can do.

According to the invention described in claim 7 , since a stimulable phosphor containing a compound satisfying the general formula (2) can be applied, the luminance of the general formula (1) is particularly high. -A high-quality phosphor plate can be produced.

According to the invention described in claim 8 , since the flattening step can be surely performed on the protruding portion, it is possible to reduce abnormal scattering and abnormal refraction of excitation light and fluorescence, and to reduce image noise. High-quality images can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail. However, the scope of the invention is not limited to the illustrated examples.

  As shown in FIG. 1, the radiation image conversion panel 1 of the present invention includes a phosphor plate 4 in which a phosphor layer 3 is formed on a predetermined support 2.

  As the support 2 used in the present embodiment, various polymer materials, glass, ceramics, metals, carbon fibers, composite materials including carbon fibers, and the like can be used, for example, quartz, borosilicate glass, chemical strengthening, and the like. Glass, glass such as crystallized glass; ceramics such as alumina and silicon silicon; plastic films such as cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, polycarbonate film; aluminum, iron, copper, A metal sheet such as chromium and a metal sheet having a coating layer such as hydrophilic fine particles are preferable.

  Further, the surface 2a of the support 2 may be a smooth surface, or may be a mat surface for the purpose of improving the adhesion to the phosphor layer 3. Furthermore, in order to improve the adhesiveness between the support 2 and the phosphor layer 3, an adhesive layer may be provided on the surface 2a in advance as necessary.

  The phosphor layer 3 is composed of at least one layer and varies depending on the type of phosphor, but the layer thickness is 50 μm or more, and more preferably in the range of 50 to 1000 μm from the viewpoint of obtaining the effects of the present invention. The phosphor layer 3 has a columnar structure in which a large number of columnar crystals 3a, 3a,. (See FIG. 3).

Here, the phosphor constituting the phosphor layer 3 will be described in detail.
As the phosphor, a stimulable phosphor is preferable, and in particular, a stimulable phosphor containing a compound represented by the general formula (1) can be used.

M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : eA (1)

Here, M ¹ is preferably at least one alkali metal atom selected from the group consisting of Li, Na, K, Rb and Cs, more preferably a Cs atom.

M ² is at least one divalent metal atom selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu, and Ni, and in particular, selected from Be, Mg, Ca, Sr, and Ba. And at least one kind of atom.

M ³ is at least one selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, and In. In particular, it is preferably at least one atom selected from the group consisting of Y, La, Ce, Sm, Eu, Gd, Lu, Al, Ga, and In.

  X, X ′, and X ″ are at least one halogen selected from the group consisting of F, Cl, Br, and I, and particularly preferably at least one atom selected from the group consisting of Br and I, and more preferably Br. Is an atom.

  A is at least selected from the group consisting of Eu, Tb, In, Ga, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg. It is preferably a kind of metal atom, particularly at least one kind of metal atom selected from the group consisting of Eu, Cs, Sm, Tl and Na, and more preferably an Eu atom.

  a, b, and e are numerical values in the ranges of 0 ≦ a <0.5, 0 ≦ b <0.5, and 0 <e ≦ 0.2, respectively.

  Here, the alkali halide phosphor is particularly preferable because it is easy to form a columnar stimulable phosphor by a method such as vapor deposition or sputtering. Among them, a compound represented by the following general formula (2) is particularly preferable. It is preferable to have a photostimulable phosphor that contains.

CsX: yA (2)
Here, X is Cl, Br or I, A is Eu, Sm, In, TI, Ga or Ce, and e is a numerical value in the range of 0.0000001 ≦ e ≦ 0.01. In particular, y can be expected to improve X-ray conversion efficiency and to have high luminance and high image quality when Eu is used as an activator.

  Moreover, in the radiographic image conversion panel 1, the protective layer which protects the fluorescent substance plate 4 is provided as needed. The protective layer includes two moisture-proof protective films 5 and 6, and the phosphor plate 4 includes a first moisture-proof protective film 5 disposed on the upper side of the phosphor layer 3 as shown in FIG. The second moisture-proof protective film 6 disposed below the support 2 is interposed between the second moisture-proof protective film 6 and the second moisture-proof protective film 6.

  In the radiation image conversion panel 1, the peripheral portions of the first and second moisture-proof protective films 5 and 6 are fused over the entire circumference, and the first and second moisture-proof protective films 5 and 6 fluoresce. The body plate 4 is completely sealed. The first and second moisture-proof protective films 5 and 6 seal the phosphor plate 4 to prevent moisture from entering the phosphor plate 4 and to prevent dust and scratches on the phosphor surface. The phosphor plate 4 is protected by preventing the adhesion.

  As the material used for the protective layer, polyalkylene film, polyester film, polymethacrylate film, nitrocellulose film, cellulose acetate film and the like can be used. For example, polypropylene film, polyethylene terephthalate film, polyethylene naphthalate film and the like are transparent. From the viewpoint of property and strength.

  In order to improve moisture resistance, it is more preferable to use a film in which a material that does not easily transmit water vapor and oxygen, such as alumina or silica, is used as the protective layer. In addition, a glass substrate can also be used.

  Then, the manufacturing method of the radiographic image conversion panel 1 which concerns on this invention is demonstrated.

  First, a predetermined support 2 is prepared, and a phosphor layer 3 is formed on the support 2 by a known vapor deposition method as shown in FIG.

  For example, the case where the phosphor layer 3 is formed by a vapor deposition method among a plurality of well-known vapor deposition methods will be briefly described. The support 2 is fixed and installed on a support holder in a vapor deposition apparatus, and the vapor deposition is performed. The inside of the apparatus is evacuated to a certain degree of vacuum. Thereafter, the phosphor is heated and evaporated using a resistance heating method, an electron beam method, or the like as a vapor deposition source, and the phosphor is grown on the surface 2a of the support 2 until a desired thickness is obtained. The body layer 3 is formed on the support 2.

  Then, on the surface of the phosphor layer 3, as shown in FIG. 4, a phosphor having a structure in which columnar crystals 3a having a length of several tens to several hundreds of μm and an average diameter of several μm are regularly arranged can be formed.

  However, when the phosphor is grown on the surface 2 a on the support 2, bumping occurs from the heated and melted phosphor, or scratches or dust are generated on the surface 2 a on the support 2 in the manufacturing process. As shown in FIG. 5, the columnar crystal 3a partially grows abnormally compared to the surrounding area as shown in FIG. 5 using the foreign matter on the surface 2a or the surface of the growing phosphor as a nucleus. There is a case where the protruding portion 7 that protrudes compared to the portion is generated.

  Then, on the surface of the phosphor layer 3, the excitation light irradiated to the radiation image conversion panel 1 is scattered or refracted in unnecessary directions by the protrusions, and the stimulated light generated by the excitation is the same. In addition, image noise such as speckles is generated by causing scattering and refraction different from the normal part, resulting in deterioration of image quality.

  Therefore, when the phosphor layer 3 is formed on the support 2, a determination process is performed on the phosphor layer 3, and then a flattening process is performed based on the determination result, whereby the protrusion 7 is formed. Predetermined processing is performed to produce a phosphor plate 4 with good image quality.

  Here, the determination process and the planarization process are performed using a processing apparatus 10 as shown in FIG.

  As shown in FIG. 6, the processing apparatus 10 includes an XY stage 11 that supports the phosphor plate 4 so as to be movable in the XY direction. Above the XY stage 11 is provided a microscope optical system 13 provided with a high power laser head 12 for irradiating a laser for flattening processing. Here, the optical axis of the laser irradiated from the high power laser head 12 is shown as the optical axis 14.

In order to excite the phosphor in the phosphor plate 4, the microscope optical system 13 is provided with an excitation UV illumination 15 that irradiates excitation light such as ultraviolet rays (UV). The excitation UV illumination 15 has a lens 16 and a reflection mirror 17 disposed at a predetermined angle with respect to the optical axis 14 so that the surface of the phosphor plate 4 can be irradiated coaxially with the optical axis 14. And an optical system (not shown) for irradiating the phosphor plate 4 on the XY stage 11 with spot-shaped excitation light having a predetermined shape and size through the objective lens 18, and excitation UV illumination. The excitation light emitted from 15 passes through the lens 16 and is reflected by the reflection mirror 17, and then radiates in a spot shape to the phosphor plate 4 on the XY stage 11 through the objective lens 18. In the spot irradiated with excitation light in the form of a spot on the body plate 4, fluorescence (instantaneous light emission) is emitted. For example, when CsBr: Eu ²⁺ , which is a stimulable phosphor, is used as the phosphor material, when excited by X-rays, it is excited in addition to storing a latent image on the phosphor plate 4 as stimulating light. It causes so-called instantaneous light emission that emits fluorescence at the moment when it is emitted. The fluorescence generated by the instantaneous light emission can be excited even by light in the ultraviolet region. In the case of CsBr: Eu ²⁺ , when the phosphor plate 4 is irradiated with excitation light of about 360 nm by the excitation UV illumination 15, it is 440 nm. It is possible to emit nearby fluorescence. The excitation UV illumination 15 is not limited as long as it can excite the phosphor in the phosphor plate 4, and excitation light illumination that emits electromagnetic waves such as light other than UV and radiation can be applied. Is possible.

  The microscope optical system 13 includes a CCD camera 19 that observes the surface of the phosphor plate 4. The CCD camera 19 has a reflection mirror 20 that is coaxial with the optical axis 14 and arranged at a predetermined angle with respect to the optical axis 14 so as to capture an image of the surface of the phosphor plate 4, and a lens 21. The fluorescence emitted from the phosphor plate 4 is incident through the objective lens 18 and the reflecting mirror 20 (two-dot chain line) to obtain an image. As the CCD camera 19, a conventionally known one can be applied, and the size of the image obtained by the CCD camera 19 can be easily adjusted by changing the magnification of the objective lens 18.

  Here, the reflection mirrors 17 and 20 provided in the microscope optical system 13 will be described. As the reflection mirrors 17 and 20, a microscope optical system 13 may be provided with a mirror having spectral characteristics of transmittance and reflectance, or the mirror may be irradiated with excitation light by an excitation UV illumination 15 or a CCD. An insertion / extraction mechanism that is inserted into the microscope optical system 13 only when the surface of the phosphor plate 4 is observed by the camera 19 may be provided. The former reflection mirrors 17 and 20 may be mirrors provided with a coating that has a high transmittance for the wavelength of the laser emitted from the high-power laser head 12 and that enhances the reflectance in the ultraviolet region. Thus, it can be realized by selecting a coating that minimizes both the mirror transmission loss during laser processing and the excitation light and fluorescence reflection loss during excitation light / fluorescence observation. On the other hand, the latter reflecting mirrors 17 and 20 can be realized by using an insertion / extraction mechanism that switches the optical path during laser processing, ultraviolet excitation, and fluorescence observation.

  A processing device (not shown) is connected to the CCD camera 19. The processing device is for measuring and determining the state of the surface of the phosphor plate 4 based on information photographed by the CCD camera 19. Here, the phosphor is based on the image photographed by the CCD camera 19. The fluorescence emitted from the plate 4 is imaged and digitized using average luminance or the like to determine abnormality. For example, in the processing apparatus, the brightness of a predetermined numerical value is detected at a place (normal place) where the surface of the phosphor plate 4 is flat as shown in FIG. 4, whereas the phosphor plate shown in FIG. In the protruding portion 7 on the surface 4, a numerical value of brightness different from that of the normal part is detected, and it is determined that there is an abnormality. This is because, when the phosphor plate 4 emits fluorescence by the light emitted from the excitation UV illumination 15, the incident light and the emitted light are abnormally scattered or refracted at the protrusion on the surface of the phosphor plate 4. This is because it is observed as a brightness different from the normal location.

  In addition, the processing apparatus stores a location determined to be abnormal (abnormal location) as a protruding portion in association with a position on the phosphor plate 4 and stores the difference between the luminance at the abnormal location and the luminance at the normal location (luminance). (Difference) is converted and stored as a protrusion amount.

  Next, the high power laser head 12 will be described. The high power laser head 12 is for irradiating the phosphor plate 4 on the XY stage 11 based on the information determined by the processing apparatus, and is irradiated from the high power laser head 12. The laser is connected to a beam spot of a predetermined size (dotted line) on the phosphor plate through a beam shaping optical system (not shown) provided in the high power laser head 12 and the microscope optical system 13 and the objective lens 18. ing.

  Here, the high-power laser head 12 partially removes the surface of the phosphor layer 3 irradiated with the laser in the layer thickness direction of the phosphor layer 3 by a laser ablation method, that is, a protrusion on the surface of the phosphor layer 3. 7 is for instantly and locally raising the temperature to cause pyrolysis, gasification, etc., removing a certain amount in the phosphor layer thickness direction, and flattening the phosphor layer 3 surface. Here, the laser irradiation is performed on the protruding portion 7 on the phosphor plate 4 stored in the processing apparatus from the inspection result.

  Examples of the laser include a YAG laser and a CO2 laser. Also, it is possible to use a laser converted into various wavelengths by incorporating a nonlinear optical crystal into the laser. For example, in the case of a YAG laser, it is possible to use wavelengths such as second harmonic = 532 nm (green), third harmonic = 355 nm (ultraviolet), and fourth harmonic = 266 nm (ultraviolet) with respect to the fundamental wavelength of 1064 nm. In addition, it is possible to select a wavelength that is advantageous for processing on the optical properties of the crystal such as the light absorption and reflection of the phosphor crystal constituting the phosphor plate 4 and the photochemical reaction. In addition, when selecting the wavelength, not only the wavelength advantageous for processing is selected, but also comprehensively evaluated in consideration of the damage to the phosphor plate 4 and the influence on the fluorescence emission characteristics with respect to the specific wavelength, It is preferable to select the laser wavelength to be used.

  Further, the high power laser head 12 has a laser emission port or a laser beam optical axis 14 between the emission port and the objective lens in order to obtain an image (spot diameter) of a desired size on the surface of the phosphor plate 4. An aperture having an appropriate size or a lens for beam shaping may be provided on the top. Alternatively, the spot diameter can be changed by changing the magnification of the objective lens 18 described above.

  Further, the intensity of the laser emitted from the high power laser head 12 is adjusted based on the luminance difference stored in the processing apparatus, and the adjustment of the amount of excavation of the protruding portion is detected in the determination process. It is determined according to the amount of protrusion.

FIG. 7 shows the relationship between laser conditions and excavation amount. In FIG. 7, using a YAG laser having a harmonic generation function in the high-power laser head 12, the wavelengths are 1064 nm and 355 nm, and the beam diameters on the phosphor surface are about 100 μm, 1064 nm, and 355 nm. When the average output is 0.56 mJ and 0.21 mJ, the repetition frequency (pulse frequency) of pulse emission is set to 50 Hz (pulse width; about 10 nsec), and the laser irradiation energy irradiated on the phosphor surface is changed. A graph of the amount of phosphor removed (digging amount) on the surface of the phosphor to be removed is shown in a graph. Here, the laser irradiation energy indicates the pulse number (irradiation pulse number) of the laser irradiated on the phosphor surface. Note that a columnar crystal of CsBr: Eu ^{2+ having} a total layer thickness of about 350 μm was used for the phosphor subjected to the removal processing.

  According to FIG. 7, it is shown that the excavation amount increases with the number of irradiated pulses when the number of irradiation pulses exceeds a certain number of irradiation pulses regardless of the wavelength of 1064 nm or 355 nm. It is possible to control the amount of excavation on the body surface. Therefore, it becomes possible to determine the target excavation amount based on the numerical results shown in the figure and control the laser conditions. The conditions include the manufacturing conditions (mainly vapor deposition conditions) of the phosphor plate 4, the crystal structure thereof, the type of phosphor material constituting the plate, the hardness of the crystal, the degree of brittleness, and the laser ablation reaction. Therefore, before using the high-power laser head 12, the relationship between the number of irradiation pulses and the amount of excavation on the phosphor surface is measured in advance using the phosphor material to be used and its manufacturing conditions. It is possible to perform highly accurate processing by determining processing conditions to be applied to the high power laser head 12 based on the above.

  As a method for adjusting the intensity (irradiation intensity) of the laser applied to the phosphor plate 4, it is possible to adjust the light quantity by mounting an appropriate optical attenuator on the optical path of the laser. Or, for example, when a YAG laser is pulse-oscillated by flash lamp excitation or the like, when irradiating the laser, the irradiation intensity is adjusted by the number of times of pulse oscillation, or the pulse is oscillated at a constant period, and irradiation is performed for the irradiation time It is also possible to adjust the strength.

  When the determination process and the planarization process are performed using the processing apparatus 10 described above, first, the phosphor plate 4 manufactured by the above-described method is mounted on the XY stage 11, and the excitation UV illumination 15 is turned on. Let Then, the phosphor plate 4 is irradiated with excitation light from the excitation UV illumination 15, and the phosphor is excited and emits fluorescence (instantaneous light emission) at the portion irradiated with the excitation light.

  Then, the emission state of the emitted fluorescence is photographed by the CCD camera 19, and it is determined by the processing device whether the portion of the phosphor plate 4 is abnormal or normal. In addition to the luminance difference, the abnormal portion of the phosphor plate 4, that is, the protruding portion 7 is stored.

  Then, the remaining portions of the phosphor plate 4 are similarly scanned by moving the XY stage 11 to determine the fluorescence image of the entire surface of the phosphor plate 4.

  After the determination step is performed in this manner, the high power laser head 12 determines the irradiation intensity for the portion determined to be abnormal, that is, the protrusion 7 based on the luminance difference stored in the processing device. Adjust and irradiate with laser. Then, the temperature rises instantaneously and locally at the protrusion 7 to cause thermal decomposition, gasification, and the like, and a certain amount of phosphor is excavated in the phosphor layer thickness direction. As a result, the protruding portion 7 existing before the laser irradiation is partially removed, and the phosphor surface becomes flat as shown in FIG.

After performing the determination step and the planarization step as described above, a protective layer is provided as necessary. The protective layer may be formed, for example, by covering two surfaces of the phosphor plate 4 with two moisture-proof films having heat-fusibility and heating and pressurizing the peripheral portion with an impulse heater or the like, or separately formed in advance. The protective layer thus formed may be adhered to the phosphor layer 3. In addition, the protective layer may be formed by directly applying a material for the protective layer to the surface of the phosphor layer 3, or by an inorganic material such as SiC, SiO ₂ , SiN, Al ₂ O ₃ by vapor deposition or sputtering. May be laminated. In addition, the layer thickness of the protective layer is preferably 0.1 to 2000 μm.

  In the radiation image conversion panel 1 manufactured by the method as described above, the flattening process is not performed on the phosphor plate 4 in which the phosphor layer 3 is formed on the conventional support by the vapor deposition method. In comparison, since only the protrusion 7 on the phosphor surface can be flattened and the surface of the phosphor layer 3 can be flattened, abnormal scattering and abnormal refraction of excitation light and fluorescence can be reduced, and image noise can be reduced. Generation can be reduced and a high-quality image can be obtained.

  In particular, when a protective layer is provided on the phosphor plate 4, the surface of the phosphor layer 3 can be blocked from the outside, and can be protected from physical and chemical damage to the surface of the phosphor layer 3. it can. In general, phosphors are highly hygroscopic, and phosphor plates are particularly susceptible to deterioration due to moisture absorption, but the protective layer can prevent deterioration due to moisture absorption and maintain high-quality images. it can. At this time, since the protruding portion 7 does not exist between the protective layer and the phosphor plate 4, the shape deformation given to the protective layer by the protruding portion 7, and accordingly, in the protective layer and between the protective layer and the phosphor layer. Anomalous scattering and anomalous refraction that occur at the interface can be reduced, and image noise can be reduced to obtain a high-quality image.

  Of course, the present invention is not limited to the above-described embodiment and can be modified as appropriate.

  For example, in the determination step according to the present embodiment, the phosphor plate 4 is irradiated with excitation light and the fluorescence difference in the image obtained by reading the fluorescence emitted from the phosphor plate 4 is determined. Although the protrusion 7 and the protrusion amount are converted and detected, the protrusion amount of the protrusion 7 on the phosphor plate 4 may be measured with respect to the phosphor plate 4 by a contact / non-contact displacement sensor.

  Alternatively, the excitation UV illumination 15 of FIG. 6 is used as a general illumination white light source, and the surface image of the phosphor plate 4 is imaged by the CCD camera 19 and the focus position at the time of imaging is measured. The amount of protrusion may be obtained from the difference from 7.

  In the planarization step, a laser is used as a means for partially removing the surface of the phosphor layer 3 in the layer thickness direction of the phosphor layer 3 by laser ablation. However, instead of the laser, the same reaction as the laser is used. May be performed using microwaves, plasma, accelerated ions, accelerated electrons, or the like that can be obtained.

  Moreover, as the planarization step, the surface of the phosphor layer 3 was partially removed in the layer thickness direction of the phosphor layer 3 by a laser ablation method. However, in the planarization step, the surface of the phosphor layer 3 was locally removed. It may be melted. In this case, it is possible to flatten the surface of the phosphor layer 3 by melting the protrusions 7 on the phosphor surface with heat. Further, local melting of the surface of the phosphor layer 3 can be performed using light such as laser, microwave, plasma wave or the like. Whether the surface of the phosphor layer 3 is ablated or melted is naturally determined from the material and crystal structure of the phosphor layer 3, the purpose of use, or determined by the light output method, What is necessary is just to select suitably according to a usage form.

  Further, the planarization step may be performed by a so-called calendar process performed using a heating / pressurizing roll. In this case, by passing the phosphor plate 4 between a pair of heating or pressure rollers, the protrusions 7 on the phosphor plate 4 are crushed and the surface of the phosphor layer 3 can be flattened. Is possible.

  Further, the determination step and the planarization step may be performed repeatedly. In this case, the determination step and the flattening step can be performed again after the flattening step, and the result of the determination step and the result of the flattening step can be fed back, so that the surface of the phosphor plate 4 can be fed back. The projection can be flattened more finely according to the state.

  Also, there is a suction step for sucking / removing the sections of the protrusions scattered by the ablation by using a suction machine at the same time as the flattening step or after the flattening step and before the step of providing the protective layer. Also good. In this case, the sections scattered in the flattening step are removed, and the surface of the phosphor layer 3 can be further flattened. Moreover, a suction process may remove a foreign material with a solvent or an adhesive roll instead of attracting | sucking.

  Further, the planarization step may be performed before the step of providing the protective layer on the phosphor plate 4 or after peeling off the protective layer provided after the protective layer is provided. In that case, the phosphor plate 4 However, depending on the material of the protective layer used, the type of phosphor, and the characteristics of the irradiated laser (wavelength, intensity, etc.), The surface of the phosphor plate 4 can be flattened. For example, when glass or a resin film is used for the protective layer, a laser having a wavelength that is very low in absorption by the protective layer is used as the processing laser, and the laser beam is transmitted in a state where the beam diameter on the protective layer is increased. What is necessary is just to design the optical system by which beam shaping was carried out so that the beam diameter on a crystal plane might become a minute spot. By doing so, it is possible to perform the planarization step with the protective layer applied while minimizing damage to the protective layer by the laser, and flatten only the protrusions generated on the surface of the phosphor plate 4. Can be processed.

It is a figure which shows the radiographic image conversion panel which concerns on embodiment of this invention. It is the schematic which shows 1 process of the manufacturing method of the radiographic image conversion panel which concerns on embodiment of this invention. It is a figure which shows a mode that a fluorescent substance layer is formed in a support body by a vapor deposition method. It is a schematic diagram which shows the state of the normal fluorescent substance layer surface. It is a schematic diagram which shows the state by which the protrusion part was formed in the fluorescent substance layer surface. It is a figure which shows the processing apparatus used for the manufacturing method of the radiographic image conversion panel which concerns on embodiment of this invention. It is the graph shown about the relationship between laser irradiation energy and the amount of excavation. It is a schematic diagram which shows the state by which the protrusion part formed in the fluorescent substance layer surface was planarized.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radiation image conversion panel 2 Support body 3 Phosphor layer 4 Phosphor plate 5 1st moisture-proof protective film 6 2nd moisture-proof protective film 7 Protrusion part 10 Processing apparatus 11 XY stage 12 High power laser head 13 Microscope Optical system 14 Optical axis 15 Excitation UV illumination 16, 21 Lens 17, 20 Reflection mirror 18 Objective lens 19 CCD camera

Claims (8)

In the method of manufacturing a radiation image conversion panel that forms a phosphor plate composed of a support and a phosphor layer formed on the support through a vapor deposition step,
After the vapor deposition step, based on the luminance difference from the phosphor plate, a determination step of determining the presence and the amount of protrusion on the phosphor layer surface, and
After the determination step, the phosphor layer surface is partially removed in the layer thickness direction of the phosphor layer by laser ablation, or the phosphor plate is interposed between a pair of heating rollers or pressure rollers by calendering to pass, the production of a radiation image conversion panel and having and a flattening step of flattening only the protruding portion present in the phosphor layer on the surface in accordance with the determination result in said determining step Method.   The method for manufacturing a radiation image conversion panel according to claim 1, wherein the phosphor plate has a protective layer provided so as to cover the surface of the phosphor layer. After the deposition step, the determining step and the method of manufacturing the radiation image conversion panel according to claim 1 or claim 2, characterized in that repeatedly performing the planarization process. The method for manufacturing a radiation image conversion panel according to any one of claims 1 to 3 , wherein the phosphor layer is made of a phosphor formed by a vapor deposition method. The said fluorescent substance is a stimulable fluorescent substance, The manufacturing method of the radiographic image conversion panel as described in any one of Claims 1-4 characterized by the above-mentioned. The method for producing a radiation image conversion panel according to claim 5 , wherein the photostimulable phosphor contains a compound having a composition represented by the following general formula (1).
M1X · aM2X ′ ₂ · bM3X ″ ₃ : eA (1)
[Wherein M1 is at least one alkali metal selected from Li, Na, K, Rb and Cs, and M2 is selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd, and Ni. M3 is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga and In. At least one trivalent metal selected from the group consisting of: X, X ′ and X ″ are at least one halogen selected from the group consisting of F, Cl, Br and I, and A is Eu, Tb, At least one metal selected from the group consisting of In, Ga, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, TI, Na, Ag, Cu, and Mg. Yes, a, b, Each represents a number between 0 ≦ a <0.5,0 ≦ b <0.5,0 <e ≦ 0.2.] The method of manufacturing a radiation image conversion panel according to claim 5 or 6 , wherein the photostimulable phosphor contains a compound having a composition represented by the following general formula (2).
CsX: yA (2)
[Wherein X is Cl, Br or I, A is Eu, Sm, In, TI, Ga or Ce, and e is a numerical value in the range of 0.0000001 ≦ e ≦ 0.01. ] In a radiation image conversion panel provided with a phosphor plate composed of a support and a phosphor layer formed on the support through a vapor deposition step,
The phosphor plate has the phosphor according to a result determined by a determination step of determining the presence / absence of a protrusion on the surface of the phosphor layer and a protrusion amount based on a difference in light emission luminance from the phosphor plate. Flattening by partially removing the surface of the layer in the thickness direction of the phosphor layer by a laser ablation method, or by calendering that passes the phosphor plate between a pair of heating rollers or pressure rollers A radiation image conversion panel, wherein only the protrusions present on the surface of the phosphor layer are flattened by the flattening step.

Images