JP2011027573A - Radiation image conversion panel and radiation image sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image conversion panel that enhances the reflectance without forming a reflecting layer comprising metal thin films or the like and can also exhibit the higher reflectance than that when a reflecting layer is made of spherical crystal particles and a method for manufacturing the panel. <P>SOLUTION: In the radiation image conversion panel 10, a radiation conversion layer 2 which converts incident radiation into light is formed on a substrate 1. The radiation conversion layer 2 has a reflecting layer 3 which reflects the light toward a light emission face 2a on the side opposite to the light emission face 2a which emits the light, and the reflecting layer 3 has a helical structure where crystals of phosphors pile up helically. Moreover, the reflecting layer 3 is formed so that the reflectance on its outside domain can be higher than that on its inside domain. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiation image conversion panel and a radiation image sensor provided with a radiation conversion layer composed of a plurality of columnar crystals (needle crystals).

  Conventionally, a radiation image conversion panel including a radiation conversion layer composed of a plurality of columnar crystals (needle crystals) is known. This type of radiation image conversion panel is configured, for example, by providing a phosphor layer obtained by growing phosphor crystals in a columnar shape on a substrate made of amorphous carbon. However, since the reflectance of the substrate such as amorphous carbon is low and it is difficult to improve the light utilization efficiency as it is, conventionally, a radiation image conversion panel in which a reflective layer made of a metal thin film such as aluminum is formed is known. (For example, see Patent Documents 1 and 2). On the other hand, there is also known a radiation image conversion panel that improves the image quality of a radiation image by increasing the linearity of the columnar crystal by keeping the width of the waviness within a certain range with respect to the side surface of the columnar crystal (for example, Patent Documents). 3). Furthermore, a radiation image conversion panel having an improved reflectance without forming a reflection layer has also been known (see, for example, Patent Document 4).

JP 2002-236181 A JP 2003-75542 A JP 2005-164380 A Japanese Patent No. 3987469

  The radiation image conversion panel described in Patent Document 4 described above increases the reflectance by devising the structure of the columnar crystal.

  However, in the radiation image conversion panel described in Patent Document 4, each columnar crystal is formed by a lower layer in which a plurality of spherical crystal particles are stacked in a rosary shape in a vertical direction and a columnar crystal layer formed thereon. Therefore, there were the following problems. Here, it is assumed that there are a plurality of columnar crystals 100, 101, 102 as shown in FIG. Each of the columnar crystals 100, 101, and 102 has spherical crystal particles 100a, 100b, 100c, 101a, 101b, 101c, 102a, 102b, and 102c, which form a lower layer by overlapping in a bead shape. In addition, columnar crystal parts 100d, 101d, and 102d are stacked. In this case, when the adjacent ones of the columnar crystals 100, 101, 102 are seen, the crystal grains are in contact with each other.

  Since each crystal particle has a curved surface whose surface is curved like a spherical surface, for example, as shown in FIG. 21B, the crystal particles 100a, 100b, and 100c are adjacent crystal particles 101a and 101b, respectively. , 101c and a certain range from the most overhanging portion contact to form a contact portion c. However, since a non-contact portion appears at a location away from the contact portion c, a situation in which a gap v is formed between the adjacent columnar crystals 100 and 101 cannot be avoided.

  Therefore, in the radiation image conversion panel described in Patent Document 4, the density of the phosphor in the lower layer where the spherical crystal particles are present is low, and this lower layer functions as a reflective layer having light reflection characteristics. Could not be increased.

  Therefore, the present invention has been made to solve the above problems, and the reflectance can be increased without forming a reflective layer made of a metal thin film or the like, and the reflective layer is formed by spherical crystal particles. Another object of the present invention is to provide a radiation image conversion panel and a radiation image sensor that can exhibit a high reflectance.

  In order to solve the above problems, a radiation image conversion panel according to the present invention is a radiation image conversion panel in which a radiation conversion layer for converting incident radiation into light is formed on a substrate, and the radiation conversion layer emits light. A reflection layer that reflects light to the emission surface side on the opposite side of the light emission surface, and the reflection layer has a spiral structure in which phosphor crystals are stacked in a spiral shape, and on the inner side of the outer periphery of the substrate A radiation image conversion panel formed so that the reflectance on the outer area is higher than the inner area when the area to be arranged is the inner area and the area arranged outside the inner area is the outer area. Features.

  In this radiation image conversion panel, since the reflective layer has a spiral structure of phosphor crystals, when a large number of columnar crystals are formed on the substrate, the gaps between the columnar crystals in the reflective layer can be reduced. Further, the reflectance on the outer region can be made higher than that of the inner region by the reflective layer.

  The reflective layer may be formed so that the thickness on the outer region is thicker than the inner region, or only on the outer region. In either case, the reflectance on the outer region can be made higher than the inner region by the reflective layer.

  Further, it is preferable that the reflective layer is formed so as to gradually increase in thickness toward the outer periphery of the substrate on the outer region.

  If it does in this way, a reflective layer can make a reflectance become high, so that it approaches the outside also on an outside field.

  Further, the reflective layer is thicker on the intermediate region than on the central region when the region including the central portion of the substrate in the inner region is the central region and the region disposed outside the central region is the intermediate region. Preferably, it is formed or formed only on the intermediate region.

  In this way, the reflectance can be increased in the order of the central region, the intermediate region, and the outer region.

  The radiation conversion layer is composed of a plurality of columnar crystals in which phosphor crystals are stacked in a columnar shape, and each of the columnar crystals extends from the spiral structure to the light emitting surface side along the direction intersecting the substrate. It is preferable that the spiral structure and the columnar structure are formed by successively laminating phosphor crystals. According to this configuration, since the light reflected by the spiral structure is incident on the columnar structure laminated continuously on the spiral structure, the luminance can be increased without reducing the contrast of the radiation image.

  The radiation conversion layer is composed of a plurality of columnar crystals in which phosphor crystals are stacked in a columnar shape, a spiral structure is formed in the plurality of columnar crystals, and the first, adjacent ones of the plurality of columnar crystals, The spiral structure portion forming the spiral structure of the second columnar crystal preferably has an intrusion structure in which the second columnar crystal enters a gap that is spaced above and below the first columnar crystal. According to this configuration, the distance between the columnar crystals can be reduced while maintaining the crystal density and size of the spiral structure capable of exhibiting a sufficient reflection effect and mechanical strength, thereby reducing the radiation conversion efficiency. Without increasing brightness.

  At this time, the portion on the second columnar crystal side in the spiral structure portion of the first columnar crystal and the portion on the first columnar crystal side in the spiral structure portion of the second columnar crystal are in a direction intersecting the substrate. The gap between the spiral structure portion of the first columnar crystal and the spiral structure portion of the second columnar crystal is a wavy line when viewed from a direction orthogonal to the direction intersecting the substrate. More preferred. According to this configuration, it is possible to reliably maintain the crystal density and size of the spiral structure that can exhibit a sufficient reflection effect and mechanical strength, and to further reduce the interval between the columnar crystals.

  In the radiation conversion layer, it is preferable that a plurality of spiral loops forming a spiral structure are stacked in a direction intersecting the substrate. Alternatively, in the radiation conversion layer, a flat spherical portion forming the spiral structure is formed on the substrate. It is preferable that a plurality of layers are stacked obliquely with respect to the orthogonal direction. According to these structures, since the reflective function in a helical structure part becomes reliable, the reflectance in a reflective layer can be raised. Further, it is preferable that the flat spherical portion connected to the columnar structure in the flat spherical portion is not larger than the column diameter of the columnar structure (that is, in the direction orthogonal to the direction intersecting the substrate, The width of the flat spherical portion to be connected is preferably smaller than the width of the columnar structure. Thereby, the scintillation light generated in the vicinity of the flat spherical portion of the column diameter structure can be efficiently reflected in the tip direction without being attenuated.

  When a plurality of spiral loops are laminated in the radiation conversion layer, the reflecting layer is preferably such that the phosphor crystal is bent left and right in a cross section in a direction intersecting the surface of the substrate. More preferably, the spiral loop has an interval of about 0.67 μm to 5 μm in the direction intersecting the substrate. When the spiral loop has such an interval, it appears clearly that the phosphor crystal is bent left and right in the cross section in the direction intersecting the surface of the substrate.

  Moreover, the radiation conversion layer may be comprised by the scintillator containing CsI, and may be comprised by the photostimulable phosphor containing CsBr.

  In addition, a substrate made of a material containing carbon fiber such as CFRP has a non-uniform structure in the surface direction of the substrate as compared with a substrate made of amorphous carbon, metal, glass, or the like. Therefore, in a substrate made of a material containing carbon fiber, a difference occurs in the substrate absorption rate of emitted light, which affects the optical image output from the panel. In addition, a substrate made of a material containing carbon fiber has a structure in which radiation transmission characteristics are not uniform in the plane direction. Therefore, especially when trying to take a radiation image in a low radiation intensity state (low energy), if the transmission characteristics are different in the surface direction, the ratio of the radiation that reaches the radiation conversion layer will be uneven in the surface direction. Therefore, the obtained image is affected. A reflection film that reflects the light emitted from the radiation conversion layer can be formed between the substrate and the radiation conversion layer to increase the overall brightness and reduce this effect, but this reduces the contrast. Resulting in. On the other hand, if the configuration of the radiation image conversion panel according to the present invention is used, good luminance and contrast can be obtained even with a non-uniform substrate made of a material containing carbon fibers.

  And this invention is a radiation image sensor which has an imaging board | substrate provided with the imaging device, and the scintillator layer formed on the imaging board | substrate, Comprising: A scintillator layer has a reflective layer which reflects light to the imaging board | substrate side. The reflective layer has a spiral structure in which phosphor crystals are stacked in a spiral shape, and the area located inside the outer periphery of the imaging substrate is located inside and outside the inside area. Provided is a radiation image sensor formed so that the reflectance on the outer region is higher than the inner region when the region to be processed is the outer region.

  As described above, according to the present invention, the reflectance can be increased without forming a reflective layer made of a metal thin film or the like, and a higher reflectance can be achieved than when the reflective layer is formed of spherical crystal particles. A radiation image conversion panel with high brightness and a method for manufacturing the same can be obtained. In general, when the luminance is increased by the reflection effect, the contrast (resolution) is lowered. However, the contrast can be increased as compared with the case where a reflective layer such as a metal thin film is formed.

It is a top view of the radiation image conversion panel concerning the embodiment of the present invention. It is sectional drawing of the direction orthogonal to the board | substrate of the radiographic image conversion panel which concerns on embodiment of this invention. It is sectional drawing of the direction orthogonal to the board | substrate of the columnar crystal which comprises a radiation converting layer. FIG. 4 is a cross-sectional view in a direction orthogonal to the substrate showing the spiral structure portion of the columnar crystal of FIG. 3, (a) shows a combination of three columnar crystals, and (b) shows two columnar crystals separated from each other. It is a figure. It is a perspective view which shows the principal part of the manufacturing apparatus used for manufacture of a radiation image conversion panel. It is the figure which showed the relationship between the rotation speed difference applied at the time of manufacture, and the reflectance about the radiation image conversion panel manufactured by crystal growth by several rotation speed differences about several types of board | substrates. It is a graph which shows the relationship between a helical pitch and a reflectance about four types of board | substrates. It is a graph which shows the relationship between the film thickness of a spiral structure part, and a light output about two types of board | substrates, and the relationship between the film thickness of a spiral structure part, and CTF. FIG. 1 is a cross-sectional view in a direction perpendicular to the substrate of the radiation image conversion panel when the rotational speed difference is changed, and (a) is a curved surface that is a straight line at a portion where the boundary surface intersects the cross-section, b) shows a curved surface. It is sectional drawing of the direction orthogonal to the board | substrate of the columnar crystal which comprises the radiation conversion layer in the radiation image conversion panel of FIG. Similarly, it is sectional drawing of the direction orthogonal to the board | substrate which shows a helical structure part. It is a top view similar to FIG. 1 which shows another radiation image conversion panel. FIG. 13 is a cross-sectional view of regions showing different reflectivities in the radiation image conversion panel of FIG. 12, (a) is an outer region, (b) is an intermediate region, and (c) is a cross-sectional view of a central region. It is a top view similar to FIG. 1 which shows the radiation image conversion panel different from FIG. FIG. 15 is a cross-sectional view of regions showing different reflectivities in the radiation image conversion panel of FIG. 14, (a) is an outer region, (b) is an intermediate region, and (c) is a cross-sectional view of a central region. It is a top view similar to FIG. 1 which shows the radiation image conversion panel different from FIG. FIG. 17 is a cross-sectional view of regions showing different reflectivities in the radiation image conversion panel of FIG. 16, (a) is an outer region, (b) is an intermediate region, and (c) is a cross-sectional view of a central region. It is a top view similar to FIG. 1 which shows a radiation image sensor. FIG. 19 is a cross-sectional view of regions showing different reflectivities in the radiation image sensor of FIG. 18, (a) is an outer region, (b) is an intermediate region, and (c) is a cross-sectional view of a central region. It is a perspective view which shows the principal part of another manufacturing apparatus used for manufacture of a radiation image conversion panel. (A) is sectional drawing of the direction orthogonal to the board | substrate of the columnar crystal which comprises the radiation conversion layer of the conventional radiation image conversion panel, (b) is the figure which expanded the principal part.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

(Configuration of radiation image conversion panel)
FIG. 1 is a plan view of a radiation image conversion panel 10 according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. The radiation image conversion panel 10 includes a substrate 1 and a radiation conversion layer 2 formed on the substrate 1, and has a configuration in which the substrate 1 and the radiation conversion layer 2 are covered with a protective layer 9. The protective layer 9 is a protective film (an organic film such as polyparaxylylene, or an inorganic film) that covers at least the radiation conversion layer 2 in order to protect the radiation conversion layer 2 from moisture or the like.

  The substrate 1 is a rectangular plate made of amorphous carbon, aluminum, or the like, and the surface 1a on the side where the radiation conversion layer 2 is formed is formed flat. The radiation conversion layer 2 converts the radiation R incident from the outside of the substrate 1 into a light image corresponding to the radiation R, and the light L formed from the converted light image and a light image reflected by a reflection layer 3 described later is a light emitting surface 2a. The light is emitted from. The radiation conversion layer 2 includes the reflective layer 3 and the columnar layer 4, but has a structure in which a large number of columnar crystals 7 that are needle-shaped crystals gather as shown in FIG. The reflective layer 3 and the columnar layer 4 are formed. The thickness of the radiation conversion layer 2 is about 50 μm to about 1000 μm, and the reflective layer 3 is about 1% to 10% of the thickest part, and has a thickness of about 5 μm to about 50 μm. is doing.

  Further, in the radiation conversion layer 2, when the region disposed inside the outer periphery of the substrate 10 is an inner region, and the region disposed outside the inner region is an outer region, the reflectance on the outer region rather than the inner region. Is formed to be high. More specifically, as shown in FIG. 1, an area including four corners excluding a circular area having a radius of 10r from the center CC from the rectangular area of the substrate 1 is the outer area 10a. The circular region inside the outer region 10a is an inner region 10b, and the reflective layer 3 is formed only on the outer region 10a. Only the columnar layer 4 is formed on the inner region 10b, and the reflective layer 3 exists only on the outer region 10a. The region where the reflective layer 3 exists is hatched in FIG. Further, the reflective layer 3 on the outer region 10a exists in the range of the length r from the outer periphery and the height h from the surface 1a in the II-II line section, and the thickness is constant from the center CC toward the outer periphery. The thickness of the spiral loop gradually increases, and the number of spiral loops to be described later is the same, but the interval between the spiral loops increases toward the outer periphery. Then, as shown in FIG. 2, when the boundary surface LF between the reflective layer 3 and the columnar layer 4 is considered, the boundary surface LF is a curved surface that is a straight line at a portion that intersects the II-II line cross section.

  The columnar crystal 7 is obtained by growing a scintillator (CsI) or stimulable phosphor (CsBr) crystal as shown in FIG. A portion above 5 (on the light emission surface 2 a side) is a columnar portion 6. In each columnar crystal 7, the spiral structure portion 5 and the columnar portion 6 are integrally formed by continuously laminating crystals such as scintillators. The columnar crystal 7 is formed in a taper shape in which the outer diameter of the columnar portion 6 is smaller than the outer diameter of the spiral structure portion 5 and becomes thicker toward the tip side (opposite side of the substrate 1). And since the most advanced part has a pointed shape, the columnar part excluding the pointed part is formed in a tapered shape.

  The spiral structure portion 5 is formed by laminating crystals such as scintillators spirally from the surface 1a, and a portion of one turn around the central axis X (spiral loop) is almost regular in a direction perpendicular to the surface 1a. It has a helical structure that is formed automatically. In FIG. 3, the ranges indicated by 5A and 5B constitute one helical loop. The dimension of the spiral loop in the direction orthogonal to the surface 1a (hereinafter also referred to as “spiral pitch”) is about 0.5 μm to about 15 μm, and there are a plurality of substantially similar spiral loops (for example, about 5 to about 15). The spiral structure 5 is formed by stacking.

  Further, in the cross section in the direction orthogonal to the substrate 1a as shown in FIG. 3, the spiral structure portion 5 has a crystal such as a scintillator repeatedly bent substantially regularly on the left and right with the central axis X interposed therebetween. The bent portions 5a and 5b are connected to each other to have a bent structure. In each V-shaped portion 5a, 5b, the portion that protrudes most to the right in FIG. 3 is a folded portion 5c, and the connecting portion is a connecting portion 5d.

  The columnar portion 6 is formed as a straight portion following the spiral structure portion 5 and has a columnar structure formed by extending a crystal such as a scintillator substantially straight along a direction intersecting the surface 1a. And the helical structure part 5 and the columnar part 6 are integrally formed continuously by vapor deposition.

  In the case where the columnar crystal 7 is a scintillator crystal, the radiation incident on the columnar crystal 7 is converted into light (scintillation light), and the light is guided through the columnar portion 6 to the tip side (substrate 1). From the opposite side). In addition, when the columnar crystal 7 is a stimulable phosphor crystal, radiation information corresponding to incident radiation is accumulated and recorded. When red laser light or the like is irradiated as excitation light, light corresponding to the accumulated information is recorded. Is guided through the columnar portion 6 and emitted from the tip side (the side opposite to the substrate 1). The reflective layer 3 reflects the light guided to the reflective layer 3 side among the light guided through the columnar crystal 7 to increase the amount of light emitted from the tip side.

  As shown in FIG. 4 (a), the columnar crystal 7 has a relationship with the columnar crystals 8 and 9 on both sides, and the insertion structure in which the other enters between the vertically separated portions on one side. have. That is, as shown in FIG. 4B, which is an enlarged view of FIG. 4A, for the adjacent columnar crystals 7, 8, the V-shaped portions 5a, 5b on the right side of the connecting portion 5d of the columnar crystal 7 It has a penetration structure in which the connecting portion 5d of the columnar crystal 8 enters a gap 5e formed therebetween. In FIG. 4B, for convenience of explanation, the columnar crystals 7 and 8 are shown apart from each other, but the columnar crystals 7 and 8 are combined to form a penetration structure as shown in FIG. 4A. is doing.

  With this penetration structure, the columnar crystal 8 side portion of the columnar crystal 7 in the spiral structure portion 5 and the columnar crystal 7 side portion of the columnar crystal 8 in the spiral structure portion 5 are perpendicular to the surface 1 a of the substrate 1. Are overlapping. More specifically, the folded portion 5c of the columnar crystal 7 and the connecting portion 5d of the columnar crystal 8 overlap each other when viewed from above. The gap between the spiral structure portion 5 of the columnar crystal 7 and the spiral structure portion 5 of the columnar crystal 8 is wavy when viewed from a direction parallel to the surface 1a of the substrate 1 (side surface side of the substrate).

  Among the columnar crystals 7 having the above-described structure, the reflection layer 3 is constituted by the spiral structure portion 5, and the columnar layer 4 is constituted by the columnar portion 6. The reflection layer 3 has a function of reflecting the light L because the light L is scattered by irregularly reflecting the light L when the light L enters. Therefore, the radiation image conversion panel 10 exhibits good light reflection characteristics even if it does not have a light reflection film such as a metal film for increasing the reflectance, and can increase the amount of light emitted from the light exit surface 2a. Therefore, the sensitivity for detecting radiation can be increased. The radiation image conversion panel 10 has no risk of corrosion due to the metal film because the metal film is not formed to increase the sensitivity of detecting the radiation.

  Moreover, in the case of the radiation image conversion panel 10, the reflective layer 3 is constituted by the spiral structure portion 5 of the columnar crystal 7. As described above, since the columnar crystal 7 forms an intrusion structure in which adjacent ones in the spiral structure portion 5 enter, in the spiral structure portion 5, a space where no crystal such as a scintillator exists is extremely small. Can do. Therefore, since the density of crystals such as a scintillator in the reflective layer 3 is high, a high reflectance is exhibited.

  In the radiation image conversion panel 10, the radiation conversion layer 2 is formed with a uniform thickness from the peripheral portion of the substrate 1 to the inner portion thereof by performing vapor deposition of a scintillator using a manufacturing apparatus 50 described later. However, even if the thickness of the radiation conversion layer 2 is the same, the inclination of the columnar crystal changes in the peripheral part and the inner part (particularly the central part), and therefore the light extraction efficiency in the peripheral part deteriorates, and the luminance increases. It will deteriorate. In consideration of this point, the radiation image conversion panel 10 according to the present exemplary embodiment is configured such that the reflectance on the outer region 10a is higher than that of the inner region 10b. In the case of the radiation image conversion panel 10, the reflection layer 3 is formed only on the outer region 10a so that the reflectance on the outer region 10a is higher than that on the inner region 10b. In addition, the reflective layer 3 on the outer region 10a gradually increases in thickness toward the outer side. Therefore, in the outer region 10a, the space between the spiral loops increases toward the outside, thereby improving the scattering characteristics of the light L. Therefore, the luminance efficiency is further improved as it goes outward. ing.

(Method for manufacturing radiation image conversion panel)
A method for manufacturing the radiation image conversion panel 10 will be described. The radiation image conversion panel 10 described above can be manufactured, for example, as follows. Here, FIG. 5 is a perspective view showing a main part of the manufacturing apparatus 50 used for manufacturing the radiation image conversion panel 10. The manufacturing apparatus 50 includes a disk 51 for placing a substrate and a vapor deposition container 52. The disc 51 and the vapor deposition container 52 are housed in a vacuum device (not shown).

  The disc 51 has a mounting portion 50a on which the substrate 1 is placed in the center, and a plurality of holes 50b are formed around the mounting portion 50a for weight reduction. The vapor deposition container 52 has an annular storage portion 52a, and a vapor deposition source such as a scintillator is stored in the storage portion 52a. The storage portion 52a has a flat surface 52b on the disc 51 side closed, but a hole 52c is formed in a part thereof. The hole 52c is opened and closed by a shutter (not shown).

  Then, the disk 51 and the vapor deposition container 52 rotate by receiving a driving force from a rotation driving device (not shown) so that their respective rotation axes coincide with the axis XX. Further, the vapor deposition container 52 is heated to evaporate the vapor deposition source stored in the storage portion 52a, and the shutter is opened, and the evaporated vapor deposition source is stacked on the substrate 1 to perform crystal growth, thereby converting radiation. Layer 2 is formed.

  At that time, the rotational speed of the vapor deposition vessel 52 is made slower than the rotational speed of the disk 51 by making a difference between the rotational speeds per unit time.

  In the manufacturing apparatus 50, the number of rotations per unit time of the disk 51 (that is, the number of rotations per unit time of the substrate 1) and the number of rotations per unit time of the vapor deposition vessel 52 (that is, per unit time of the hole 52c). When the difference in rotation number is defined as a difference in rotation number, if the difference in rotation number is made smaller than a certain value (details will be described later, also referred to as critical rotation number difference), the columnar crystals 7 of the radiation conversion layer 2 are obtained. The spiral structure 5 described above appears. Therefore, crystal growth is performed in a state in which the rotational speed difference is smaller than a certain value for a certain period of time from the start of manufacture, thereby forming the above-described spiral structure portion 5. Then, the radiation image conversion panel 10 can be manufactured by increasing the rotational speed difference and forming the columnar portion 6.

  In this case, a region where the reflective layer 3 is to be formed is exposed, and a member (also referred to as a covering member, not shown) that can cover the other is placed on the substrate 1, and the rotational speed difference is made critical. Crystal growth is performed at a lower rotational speed difference. After the helical structure 5 appears, the covering member is removed, and the crystal growth is performed with the rotational speed difference higher than the critical rotational speed difference. By doing so, the radiation image conversion panel 10 is obtained.

  When crystal growth is performed while rotating the disc 51 and the vapor deposition vessel 52 as described above, the vapor deposition source overlaps or deviates from the portion on the substrate 1 where the vapor deposition source has already been deposited. It will be deposited over the position. However, when the rotational speed difference is made smaller than the critical rotational speed difference, it is considered that the deposition source tends to be stacked while gradually shifting the position so as to draw a circle from the portion where the deposition source has already been deposited. Therefore, it is considered that the crystal grows while the vapor deposition sources are spirally stacked, and the spiral structure portion 5 is formed.

  Here, FIG. 6 shows the rotation speed difference and reflection applied at the time of manufacturing the radiation image conversion panel 10 manufactured by crystal growth with several kinds of rotation speed differences using the manufacturing apparatus 50 described above. It is the figure which showed the relationship with a rate. In this embodiment, an ac (amorphous carbon) substrate, a glass substrate, a substrate A (a substrate in which aluminum is formed as a reflective film on an aluminum substrate), and a substrate B (a substrate in which aluminum is formed as a reflective film on an aluminum substrate). 4 types of substrates having a higher reflectivity than the substrate A) were prepared, and crystal growth was performed for each of them using the same vapor deposition source while changing the rotational speed difference. The rotational speed difference was made in six types: “0.4”, “0.5”, “1”, “3”, “12”, “25”. The case where the rotational speed difference is “1” corresponds to, for example, the case where the disk 51 is rotated at a rotational speed of Y [rpm] and the vapor deposition vessel 52 is rotated at a rotational speed of Y-1 [rpm]. (Y is a positive value greater than 1).

  FIG. 6 also shows the helical pitch in each radiation image conversion panel 10. As apparent from FIG. 6, the reflectance of the manufactured radiation image conversion panel 10 is higher when the difference in rotational speed is reduced to “1” than when the difference in rotational speed is “25” for any of the four types of substrates. ing. When the rotational speed difference is “25”, the spiral pitch is 0.04 μm. When the rotational speed difference is “3”, the helical pitch is 0.67 μm, and when the rotational speed difference is “1”, the spiral pitch is 0.04 μm. As the pitch difference becomes 2 μm, the spiral pitch increases as the rotational speed difference is reduced. Among these, when the rotational speed difference is reduced to “1”, the above-described bent structure appears clearly in the cross section of the radiation conversion layer 2, so that it is considered that the reflective layer 3 is constituted by the spiral structure portion 5.

  FIG. 7 is a graph showing the relationship between the spiral pitch and the reflectance for four types of substrates. As is clear from FIG. 7, the effect of improving the reflectance clearly appears for any substrate when the helical pitch is about 2 μm, that is, when the rotational speed difference is reduced to “1”. However, when the rotational speed difference is made smaller than “1” and set to “0.4”, the spiral pitch becomes 5 μm, but the reflectance in this case is almost the same as when the rotational speed difference is made “0.5”. Therefore, it is considered that the spiral pitch may be about 5 μm at most.

  In particular, in the case of an ac (amorphous carbon) substrate, even when the helical pitch is 0.67 smaller than 1 μm, that is, even when the rotational speed difference is “3”, the effect of improving the reflectance clearly appears. Therefore, the critical rotational speed difference can be set to “3” in the present embodiment.

  In the state before the radiation conversion layer 2 is formed, the ac (amorphous carbon) substrate shows a dark black color, while changing the helical pitch (changing the rotational speed difference as described above). ) When the radiation conversion layer 2 is formed, the color of the substrate gradually decreases from black to dark gray, gray, and light gray as the helical pitch becomes longer (the difference in rotational speed becomes smaller). This indicates that the reflectance of the radiation conversion layer 2 increases as the helical pitch increases.

  FIG. 8A shows the thickness and light of the spiral structure portion 5 for two types of substrates, a substrate C (a substrate in which aluminum is formed as a reflective film on an aluminum substrate) and an ac (amorphous carbon) substrate. It is the graph which showed the relationship with an output. FIG. 8B is a graph showing the relationship between the film thickness of the spiral structure portion 5 and the CTF (Contrast Transfer Function: image resolution) for two types of substrates, the substrate C and the ac substrate. FIG. 8 shows that although a high CTF is shown if the thickness of the spiral structure portion 5 is about 50 μm, the CTF gradually decreases when the thickness of the spiral structure portion 5 is larger than about 50 μm. Is done. Therefore, the film thickness of the spiral structure portion 5 is preferably about 10 μm to 50 μm.

(Configuration of another radiation image conversion panel)
On the other hand, when the rotational speed difference is “3”, the radiation conversion layer 12 different from the radiation conversion layer 2 is formed on the substrate 1. Here, FIG. 9 is a cross-sectional view in a direction orthogonal to the substrate of the radiation image conversion panel 20 on which the radiation conversion layer 12 is formed, and FIG. (B) is a case where the boundary surface LF is a curved surface. FIG. 10 is a cross-sectional view similar to FIG. 9 showing the two helical structures 15 constituting the reflective layer 13 of the radiation conversion layer 12, and FIG. 11 is a cross-sectional view similar to FIG. 9 showing the helical structures 15. .

  The radiation conversion layer 12 is different from the radiation conversion layer 2 in that it includes a reflective layer 13. The reflective layer 13 is different from the reflective layer 3 in that the base portion 1 side portion of the columnar crystal 7 is a spiral structure portion 15. The spiral structure portion 15 has a plurality of flat spherical portions 15a, and each flat spherical portion 15a is inclined with respect to the central axis X (a flat plane N described later is inclined with respect to the central axis X). ). Each flat spherical portion 15a has a structure in which a spherical body is shrunk in a specific direction (for example, up and down direction) and a side surface portion is projected, and a surface passing through the most projected portion is a flat plane N. ing. The flat spherical portion 15a is not limited to a spherical body contracted in a specific direction, and is a portion corresponding to each spiral loop when the above-described spiral loops are in contact with each other (when they are in contact in the vertical direction). May be. Further, the flat spherical portion 15 a connected to the columnar portion 6 (that is, the uppermost portion of the flat spherical portion 15 a) does not become larger than the column diameter of the columnar portion 6. As a result, the scintillation light generated in the vicinity of the flat spherical portion of the column diameter portion can be efficiently reflected in the tip direction without being attenuated.

  Further, as shown in detail in FIG. 11, the radiation conversion layer 12 is obtained by overlapping an ellipse composed of a crystal such as a scintillator in a state inclined with respect to the central axis X in a cross section perpendicular to the substrate 1 a. It has a continuous elliptical structure. In each columnar crystal 7, the spiral structure portion 15 and the columnar portion 6 are integrally formed by continuously laminating crystals such as scintillators.

  As shown in FIG. 10, the columnar crystal 7 has a relationship with the adjacent columnar crystal 8, and a portion of the other flat spherical portion 15a enters between the flat spherical portions 15a on one side. It has a structure. Due to this penetration structure, the columnar crystal 8 side portion of the columnar crystal 7 on the spiral structure portion 15 and the columnar crystal 7 side portion of the columnar crystal 8 on the columnar crystal 7 side are perpendicular to the surface 1 a of the substrate 1. Are overlapping. The gap between the spiral structure portion 15 of the columnar crystal 7 and the spiral structure portion 15 of the columnar crystal 8 is wavy when viewed from a direction parallel to the surface 1a of the substrate 1 (side surface side of the substrate).

  In such a radiation image conversion panel 20, the reflection layer 13 is configured by the spiral structure portion 15. However, since the spiral structure portion 15 has an insertion structure, the spiral structure portion 15 has a crystal such as a scintillator. The space where there is no can be made small. Therefore, since the density of crystals such as a scintillator in the reflective layer 13 is high, a high reflectance is exhibited.

  The radiation image conversion panel 20 is obtained when the rotational speed difference is set to about “3” in the manufacturing apparatus 50 described above. Even if the rotational speed difference is about “3”, the vapor deposition source is stacked while gradually shifting the position from the portion where the vapor deposition source is already vapor deposited. In this case, the rotational speed difference is set to about “1”. The tendency of vapor deposition to overlap the same portion becomes more significant than in the case, and thus the crystal grows in a state where the vertical interval of the spiral loop is narrowed and collapsed. Therefore, it is considered that the spiral structure portion 15 is formed.

  Next, FIG. 12 is a plan view similar to FIG. 1 showing another radiation image conversion panel 30, and FIG. 13 is a cross-sectional view of regions showing different reflectances in the radiation image conversion panel 30. Similar to the radiation image conversion panel 10, the radiation image conversion panel 30 has a structure in which the radiation conversion layer is different between the outer region and the inner region. Of the inner region 10b, the region including the center CC of the substrate 1 is the central region 10c. When the region disposed outside the central region 10c is the intermediate region 10e, the reflective layer 13 is formed only on the intermediate region 10e, and the reflective layer 13 is not formed in the central region 10c. ing. The reflective layer 13 is thicker on the outer region 10a than on the intermediate region 10e. Specifically, as shown in FIG. 13, when the thickness of the reflective layer 13 on the intermediate region 10e is hh, the thickness on the outer region 10a is twice as large as hh (2 × hh). When the reflective layer 13 is formed in this manner, the reflectance of the intermediate region 10e can be made higher than that of the central region 10c, and the reflectance on the outer region 10a can be further increased. Therefore, the radiation image conversion panel 30 has a high reflectance in three stages in the order of the central region 10c, the intermediate region 10e, and the outer region 10a.

  The radiation image conversion panel 30 shown in FIG. 13 has a structure in which the reflective layer 13 is not formed in the central region 10c. However, as shown in FIGS. 14 and 15, the reflective layer 13 is formed in the central region 10c. It can also be set as the radiation image conversion panel 31 of the structure to do. In this case, the thickness of the reflective layer 13 in the central region 10c can be made thinner than that of the reflective layer 13 on the intermediate region 10e to be half of hh (hh / 2).

  Further, the radiation image conversion panel 32 shown in FIGS. 16 and 17 may be used. In the radiation image conversion panel 32, reflection layers having the same thickness and different reflectances are formed in the outer region 10a, the intermediate region 10e, and the central region 10c, respectively. That is, the reflective layer 3 is formed on the outer region 10a, the reflective layer 13 is formed on the intermediate region 10e, and the reflective layer 23 is formed on the central region 10c. The reflective layer 23 has a structure in which a plurality of spherical particles are stacked.

  In the reflective layers 3, 13, and 23, when the crystal density of the scintillator is compared, the reflective layer 3 has the highest crystal density, and then the crystal density of the scintillator decreases in the order of the reflective layers 13 and 23. Therefore, the reflectance also decreases in the order of the reflective layers 3, 13, and 23. Therefore, the reflective layer 3 having the highest reflectance is formed on the outer region 10a, the reflective layer 13 having the next highest reflectance is formed on the intermediate region 10e, and the reflective layer 23 having the lowest reflectance is formed on the central region 10c. Is formed. Even in this case, the reflectance on the outer region 10a can be made higher than the inner region 10b.

  All of the radiation image conversion panel fans 10, 20, and 30 to 32 can be manufactured using the manufacturing apparatus 54 shown in FIG. The manufacturing apparatus 54 is different from the manufacturing apparatus 50 in that it has a plurality of vapor deposition containers 53 instead of the vapor deposition containers 52. The vapor deposition container 53 is a cylindrical container in which a vapor deposition source is housed. A hole 53c is formed in a part of the vapor deposition container 53 and can be opened and closed by a shutter (not shown).

  In the case of the manufacturing apparatus 50, the disc 51 and the vapor deposition container 52 are rotated so that the respective rotation axes coincide with the axis XX. In the manufacturing apparatus 54, the plurality of vapor deposition containers 53 are arranged on one plane intersecting the axis XX, and circulate around the axis XX on the plane. In this manufacturing apparatus 54, each vapor deposition container 53 is heated to evaporate the stored vapor deposition source, and the crystal is grown by opening the shutter and laminating the evaporated vapor deposition source on the substrate 1, Radiation conversion layers 2 and 12 are formed.

  Also in this manufacturing apparatus 50, the number of revolutions per unit time of the disk 51 (that is, the number of revolutions per unit time of the substrate 1) and the number of revolutions of the vapor deposition vessel 53 per unit time (that is, the unit of the hole 53c). When the difference from the number of revolutions per hour) is defined as the difference in revolutions, the spiral structure 5 is formed in the columnar crystal 7 of the radiation conversion layer 2 by making the difference in revolutions smaller than the difference in critical revolutions. . Thereafter, the columnar portion 6 is formed by increasing the rotational speed difference.

  Further, only the holes 52c and 53c of the vapor deposition containers 52 and 53 are rotated, and the number of rotations is slowed when the reflective layer 3 (spiral structure part 5) is formed, and fast when the columnar layer 4 (columnar part 6) is formed. Of course, the radiation conversion layers 2 and 12 can be formed. Alternatively, the radiation conversion layers 2 and 12 may be prepared by rotating only the substrate 1 and slowing down the rotation speed when forming the reflective layer 3 (spiral structure portion 5) and increasing the rotation speed when forming the columnar layer 4 (columnar portion 6). Can be formed. In these cases, the rotational speed difference shown in FIG. 6 becomes the rotational speed of the substrate 1 or the holes 52c and 53c of the vapor deposition containers 52 and 53 as they are, and in each case, the reflective layer 3 (spiral structure) having the pitch shown in FIG. It is possible to form part 5).

(Configuration of radiation image sensor)
FIG. 18 is a cross-sectional view similar to FIG. 1 showing the configuration of the radiation image sensor 40 according to the present embodiment. The radiation image sensor 40 includes an imaging substrate 41 having a plurality of imaging elements 42 such as photodiodes, and the radiation conversion layer 12 is formed on a surface 41 a on the imaging substrate 41 where the imaging element 42 is formed. . The radiation conversion layer 12 includes the reflection layer 13 and the columnar layer 4, but the reflection layer 13 is formed on the surface side of the radiation conversion layer 12 on the outer region 10 a and the intermediate region 10 e. The reflective layer 13 formed on the outer region 10a is formed thicker than the reflective layer 13 formed on the intermediate region 10e. Such a radiation image sensor 40 includes the reflective layer 13 on the outer region 10a and the intermediate region 10e, so that the imaging device 42 can efficiently perform light detection even in a peripheral region where the light detection efficiency tends to be lowered. In particular, since the reflective layer 13 on the outer region 10a is formed thicker than the reflective layer 13 on the intermediate region 10e, the luminance efficiency is improved, so that the image sensor 42 can detect light more efficiently. It has become. Although not shown, in the radiation image sensor 40, the reflective layer 3 may be formed instead of the reflective layer 13, or the reflective layer having the same thickness in the outer region 10 a, the intermediate region 10 e, and the central region 10 c, respectively. 3, the reflective layer 13 and the reflective layer 23 may be formed.

  In any of the above-described radiation image sensors (FIGS. 18 and 19), radiation is incident from the reflection layer on the surface side of the scintillator layer (opposite side of the imaging substrate 41), and the scintillation light is the root of the columnar layer of the scintillator layer, that is, imaging. Light is emitted from the interface with the element and enters the image sensor.

  The above description is the description of the embodiment of the present invention, and does not limit the apparatus and method of the present invention, and various modifications can be easily implemented. In addition, an apparatus or method configured by appropriately combining components, functions, features, or method steps in each embodiment is also included in the present invention.

  For example, the reflective layer 3 may be formed on the tip side of the columnar crystal 7 (the side opposite to the substrate 1). In this case, the substrate 1 is made of a transparent light guide member such as fiber optics or fiber optical plate in which optical fibers having a size of several μm to several tens of μm are bundled. The radiation incident on the columnar crystal 7 without passing through the substrate 1 is converted into light (scintillation light), and the light is guided through the columnar portion 6 and emitted from the root side (substrate side). That is, radiation is incident from the reflective layer 3 on the surface side of the scintillator layer, and the scintillation light is emitted from the base of the columnar portion of the scintillator layer, that is, from the interface with the substrate 1. The reflective layer 3 reflects the light guided to the reflective layer 3 side among the light guided through the columnar crystals 7 and increases the amount of light emitted from the root side.

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2, 12 ... Radiation conversion layer 3, 13, 23 ... Reflection layer, 4 ... Columnar layer, 5 ... Spiral structure part, 6 ... Columnar part, 7, 8, 9 ... Columnar crystal 10, 20, 30, 31, 32 ... Radiation image conversion panel, 10a ... Outer region, 10b ... Intermediate region, 10c ... Center region, 40 ... Radiation image sensor, 50, 54 ... Manufacturing equipment, 51 ... Disc, 52, 53 ... Vapor deposition vessel .

Claims (32)

A radiation image conversion panel in which a radiation conversion layer for converting incident radiation into light is formed on a substrate,
The radiation conversion layer has a reflective layer that reflects the light to the emission surface side on the opposite side of the light emission surface that emits the light,
The reflective layer has a spiral structure in which phosphor crystals are spirally stacked, and an area disposed inside the outer periphery of the substrate is an inner area, and an area disposed outside the inner area is an outer area. A radiation image conversion panel formed so that the reflectance on the outer region is higher than that on the inner region when the region is used.   2. The radiation image conversion panel according to claim 1, wherein the reflective layer has a thickness on the outer region larger than that on the inner region, or is formed only on the outer region.   3. The radiation image conversion panel according to claim 2, wherein the reflective layer is formed so as to gradually increase in thickness toward the outer periphery of the substrate on the outer region.   The reflective layer has a thickness on the intermediate region that is larger than the central region when the region including the central portion of the substrate in the inner region is a central region, and the region disposed outside the central region is an intermediate region. The radiation image conversion panel according to any one of claims 1 to 3, wherein the radiation image conversion panel is formed thick, or is formed only on the intermediate region. The radiation conversion layer is composed of a plurality of columnar crystals in which the phosphor crystals are stacked in a columnar shape,
Each of the columnar crystals has the helical structure and a columnar structure extending from the helical structure to the light emitting surface side along a direction intersecting the substrate,
The radiation image conversion panel according to any one of claims 1 to 4, wherein the spiral structure and the columnar structure are configured by continuously laminating crystals of the phosphor.   The radiation conversion layer includes a plurality of columnar crystals in which the phosphor crystals are stacked in a columnar shape, and the plurality of columnar crystals have the spiral structure, and the first column adjacent to each other among the plurality of columnar crystals. 1. The spiral structure part forming the spiral structure of the second columnar crystal has a penetration structure in which the second columnar crystal enters a gap spaced apart above and below the first columnar crystal. The radiation image conversion panel as described in any one of Claims 1-5. The portion of the first columnar crystal on the second columnar crystal side in the spiral structure portion and the portion of the second columnar crystal on the spiral column of the first columnar crystal side are the substrate and It overlaps as seen from the crossing direction,
A gap between the spiral structure portion of the first columnar crystal and the spiral structure portion of the second columnar crystal is wavy when viewed from a direction orthogonal to the direction intersecting the substrate. The radiation image conversion panel according to claim 6.   The radiation image conversion panel according to any one of claims 1 to 7, wherein a plurality of spiral loops forming the spiral structure are stacked in the radiation conversion layer in a direction intersecting the substrate.   9. The radiation image conversion panel according to claim 1, wherein the reflective layer has a crystal of the phosphor bent to the left and right in a cross section in a direction intersecting the surface of the substrate. .   The radiation image conversion panel according to claim 8, wherein the radiation conversion layer has an interval of about 0.67 μm to 5 μm in a direction in which the spiral loop intersects the substrate.   In the said radiation conversion layer, the flat spherical part which forms the said helical structure is sloping with respect to the direction orthogonal to the said board | substrate, and it is laminated in multiple numbers, The one of Claims 1-7 characterized by the above-mentioned. The radiation image conversion panel described.   The radiation conversion panel according to claim 11, wherein the flat spherical portion connected to the columnar structure in the flat spherical portion is not larger than a column diameter of the columnar structure.   The radiation image conversion panel according to claim 1, wherein the radiation conversion layer includes a scintillator containing CsI.   The radiation image conversion panel according to claim 1, wherein the radiation conversion layer is made of a stimulable phosphor containing CsBr.   The radiation image conversion panel according to claim 1, wherein the substrate is made of a material containing carbon fiber. A radiation image conversion panel in which a radiation conversion layer for converting incident radiation into light is formed on a substrate,
The radiation conversion layer has a reflective layer that reflects the light to the emission surface side on the opposite side of the light emission surface that emits the light,
The reflective layer has a reflective structure composed of a phosphor crystal, and an area disposed inside the outer periphery of the substrate is defined as an inner area, and an area disposed outside the inner area is defined as an outer area. When formed, the radiation image conversion panel is formed so that the reflectance on the outer region is higher than that on the inner region. A radiation image sensor having an imaging substrate including an imaging element, and a scintillator layer formed on the imaging substrate,
The scintillator layer has a reflective layer on the surface side that reflects light to the imaging substrate side,
The reflective layer has a spiral structure in which phosphor crystals are spirally stacked, and an area disposed inside the outer periphery of the imaging substrate is an inner area, and an area disposed outside the inner area. A radiation image sensor characterized in that, when an outer region is formed, the reflectance on the outer region is higher than that on the inner region.   The radiation image sensor according to claim 17, wherein the reflective layer is formed so that a thickness on the outer region is larger than that on the inner region, or is formed only on the outer region.   19. The radiation image sensor according to claim 18, wherein the reflective layer is formed so as to gradually increase in thickness toward the outer periphery of the substrate on the outer region.   The reflective layer has a thickness on the intermediate region that is larger than the central region when the region including the central portion of the substrate in the inner region is a central region, and the region disposed outside the central region is an intermediate region. The radiation image sensor according to claim 17, wherein the radiation image sensor is formed thick, or is formed only on the intermediate region. The radiation conversion layer is composed of a plurality of columnar crystals in which the phosphor crystals are stacked in a columnar shape,
Each of the columnar crystals has the helical structure and a columnar structure extending from the helical structure to the light emitting surface side along a direction intersecting the substrate,
The radiation image sensor according to any one of claims 17 to 20, wherein the spiral structure and the columnar structure are configured by continuously laminating crystals of the phosphor.   The radiation conversion layer includes a plurality of columnar crystals in which the phosphor crystals are stacked in a columnar shape, and the plurality of columnar crystals have the spiral structure, and the first column adjacent to each other among the plurality of columnar crystals. 1. The spiral structure part forming the spiral structure of the second columnar crystal has a penetration structure in which the second columnar crystal enters a gap spaced apart above and below the first columnar crystal. The radiation image sensor according to any one of claims 17 to 21. The portion of the first columnar crystal on the second columnar crystal side in the spiral structure portion and the portion of the second columnar crystal on the spiral column of the first columnar crystal side are the substrate and It overlaps as seen from the crossing direction,
A gap between the spiral structure portion of the first columnar crystal and the spiral structure portion of the second columnar crystal is wavy when viewed from a direction orthogonal to the direction intersecting the substrate. The radiation image sensor according to claim 22.   The radiation image sensor according to any one of claims 17 to 23, wherein a plurality of spiral loops forming the spiral structure are stacked in the radiation conversion layer in a direction intersecting the substrate.   The radiation image sensor according to any one of claims 17 to 24, wherein the reflective layer has the phosphor crystal bent to the left and right in a cross section in a direction intersecting the surface of the substrate.   26. The radiation image sensor according to claim 24, wherein the radiation conversion layer has an interval of about 0.67 to 5 [mu] m in a direction in which the spiral loop intersects the substrate.   24. In the radiation conversion layer, a plurality of flat spherical portions forming the spiral structure are stacked obliquely with respect to a direction orthogonal to the substrate. The radiation image sensor described.   28. The radiation image sensor according to claim 27, wherein the flat spherical portion connected to the columnar structure in the flat spherical portion does not become larger than a column diameter of the columnar structure.   The radiation image sensor according to any one of claims 17 to 28, wherein the radiation conversion layer is configured by a scintillator including CsI.   The radiation image sensor according to any one of claims 17 to 28, wherein the radiation conversion layer is made of a stimulable phosphor containing CsBr.   The radiation image sensor according to any one of claims 17 to 30, wherein the substrate is made of a material containing carbon fiber. A radiation image sensor having an imaging substrate including an imaging element, and a scintillator layer formed on the imaging substrate,
The scintillator layer has a reflective layer on the surface side that reflects light to the imaging substrate side,
The reflective layer has a reflective structure composed of a phosphor crystal, and an area disposed inside the outer periphery of the imaging substrate is an inner area, and an area disposed outside the inner area is an outer area. The radiation image sensor is characterized in that the reflectance on the outer region is higher than that on the inner region.

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