Patent Number: 
Section: claims

1. A radiation image conversion panel having a radiation conversion layer, formed on a substrate, for converting an incident radiation into light;wherein the radiation conversion layer has a reflective layer, on a side opposite from a light exit surface for emitting the light, for reflecting the light to the exit surface side; andwherein the reflective layer has a helical structure comprising helically stacked phosphor crystals. 2. A radiation image conversion panel according to claim 1, wherein the radiation conversion layer is constituted by a plurality of columnar crystals in which the phosphor crystals are stacked like columns;wherein each of the columnar crystals has the helical structure formed on a root side secured to the substrate and a columnar structure extending from the helical structure to the light exit surface side along a direction intersecting the substrate; andwherein the helical structure and the columnar, structure are constructed by continuously stacking the phosphor crystals. 3. A radiation image conversion panel according to claim 1, wherein the radiation conversion layer is constituted by a plurality of columnar crystals in which the phosphor crystals are stacked like columns, the helical structure is formed on a root side of the plurality of columnar crystals secured to the substrate, and helical structure parts forming the helical structures of first and second columnar crystals adjacent to each other in the plurality of columnar crystals have a nested structure in which the second columnar crystal is nested in voids of the first columnar crystal vertically separated from each other. 4. A radiation image conversion panel according to claim 3, wherein a portion on the second columnar crystal side in the helical structure part of the first columnar crystal and a portion on the first columnar crystal side in the helical structure part of the second columnar crystal overlap each other as seen in a direction intersecting the substrate; andwherein a gap between the helical structure part of the first columnar crystal and the helical structure part of the second columnar crystal is wavy as seen in a direction orthogonal to the direction intersecting the substrate. 5. A radiation image conversion panel according to claim 1, wherein, in the radiation conversion layer, a plurality of helical loops forming the helical structure are stacked in a direction intersecting the substrate. 6. A radiation image conversion panel according to claim 5, wherein, in the reflective layer, the phosphor crystals are bent laterally in a cross section in a direction intersecting a surface of the substrate. 7. A radiation image conversion panel according to claim 5, wherein, in the radiation conversion layer, the helical loops have an interval on the order of about 0.67 μm to about 5 μm in a direction intersecting the substrate. 8. A radiation image conversion panel according to claim 1, wherein, in the radiation conversion layer, a plurality of flat spherical parts forming the helical structure are stacked obliquely with respect to a direction orthogonal to the substrate. 9. A radiation image conversion panel according to claim 8, wherein the flat spherical part connected to the columnar structure in the flat spherical parts is not greater than the column diameter of the columnar structure. 10. A radiation image conversion panel according to claim 1, wherein the radiation conversion layer is constituted by a scintillator containing CsI. 11. A radiation image conversion panel according to claim 1, wherein the radiation conversion layer is constituted by a photostimulable phosphor containing CsBr. 12. A radiation image conversion panel according to claim 1, wherein the substrate is made of a material containing a carbon fiber. 13. A method for producing a radiation image conversion panel having a radiation conversion layer, formed on a substrate, for converting an incident radiation into light;the method comprising vapor-depositing a vapor deposition source to become the radiation conversion layer onto the substrate while rotating a mount table mounting the substrate and an aperture for evaporating therethrough the vapor deposition source from a vapor deposition container accommodating the vapor deposition source about an axis of rotation extending in a direction intersecting the substrate with such a rotational speed difference that the aperture moves relatively slower than the substrate, so as to form, on a side opposite from a light exit surface for emitting the light in the radiation conversion layer, a reflective layer for reflecting the light to the exit surface side. 14. A method for producing a radiation image conversion panel according to claim 13, wherein, when constructing the radiation conversion layer by a plurality of columnar crystals in which the phosphor crystals are continuously stacked like columns, the method comprises the steps of:vapor-depositing the vapor deposition source onto the substrate while rotating the aperture at a first rotational speed, so as to form a helical structure comprising helically stacked phosphor crystals as the reflective layer, andvapor-depositing the vapor deposition source onto the substrate while rotating the aperture at a second rotational speed slower than the first rotational speed, so as to form a columnar structure extending from the helical structure to the light exit surface side along a direction intersecting the substrate integrally with the helical structure. 15. A method for producing a radiation image conversion panel according to claim 13, wherein, when constructing the radiation conversion layer by a plurality of columnar crystals in which the phosphor crystals are continuously stacked like columns, the method comprises the steps of:vapor-depositing the vapor deposition source onto the substrate while rotating the substrate at a first rotational speed, so as to form a helical structure comprising helically stacked phosphor crystals as the reflective layer; andvapor-depositing the vapor deposition source onto the substrate while rotating the substrate at a second rotational speed faster than the first rotational speed, so as to form a columnar structure extending from the helical structure to the light exit surface side along a direction intersecting the substrate integrally with the helical structure.