Radiation flood source and method for producing the same

1. A radiation flood source comprising a flat substrate having printed on at least one surface thereof a radioactive coating, which coating comprises an ink and a radioactive material selected from at least one of an α-, β- and γ-emitting nuclide selected from the group consisting of Co-57, Ba-133, Gd-153, C-14, P-33, Te-99 and mixtures thereof, which coating provides for a homogeneous or controlled inhomogeneous radiation field as evidenced by a homogeneous or controlled inhomogeneous ink pattern.

2. The radiation source of claim 1 , wherein the substrate is made from a material selected from the group consisting of paper; laminated or coated paper; board; photo paper; plastics such as polyester, polyether, polyurethane, polyethylene, polypropylene, polyvinylalcohole, polyvinylether, polyvinylester, polyvinylidene chloride, polyvinylchloride, polystyrole, acrylic acid and methacrylic acid homo- and copolymers, polycarbonate, polyamide, polyimide or polyethylene terephthalate or their mixtures; cotton; silk; cellulosic materials such as nitrocellulose; metals, metal oxides or alloys and mixtures thereof.

3. The radiation source of claim 2 , wherein the substrate is a used radiation flood source comprising a flat substrate having printed on at least one surface thereof a radioactive coating, which coaxing comprises an ink and a radioactive material selected from at least one of an α-, β- and γ-emitting nuclide selected from the group consisting of Co-57, Ba-133, Gd-153, C-14, P-33, Te-99 and mixtures thereof, which coating provides for a homogeneous or controlled inhomogeneous radiation field as evidenced by a homogeneous or controlled inhomogeneous ink pattern.

4. The radiation flood source of claim 1 , further comprising a protective coating.

5. A radiation flood source according to claim 1 , obtained by a process comprising:

homogeneously dissolving the radioactive material in a suitable solvent and mixing of the thus obtained solution with an ink or directly dissolving or dispersing the radioactive material in an ink, optionally diluted with a suitable solvent to obtain a radioactive printing solution, and

printing this radioactive printing solution on the at least one surface of the substrate to provide the desired homogeneous or controlled inhomogeneous radioactive pattern by using an ink jet printer.

6. The radiation flood source of claim 1 , wherein the substrate is a sheet or foil.

7. The radiation flood source of claim 6 , wherein the substrate has circular shape with a diameter of 0.1 to 2 m.

8. The radiation flood source of claim 6 , wherein the substrate has square shape with dimensions of 0.1×0.1 m 2 to 2.0×2.0 m 2 .

9. The radiation flood source of claim 8 , wherein the substrate has DIN A4 format.

10. A radioactive printing solution comprising at least one of an α-, β- and γ-emitting nuclide selected from the group consisting of Co-57, Ba-133, Gd-153, C-14, P-33, Te-99 and mixtures thereof or mixtures of said nuclides in a form selected from the group consisting of a salt, a complex or an organic compound; an ink; and optionally a suitable solvent for dissolving said nuclide(s).

11. The radioactive printing solution of claim 10 obtained by (i) dissolving the nuclide or nuclide mixture in a suitable solvent and mixing the obtained radioactive solution with the ink or (ii) by directly dissolving the nuclide or nuclide mixture in the ink, optionally diluted with the suitable solvent.

12. The radioactive printing solution of claim 10 , comprising more than 0 to less than 100 Vol.-% of the radioactive printing solution and more than 0 to 100 Vol.-% of ink.

13. The radioactive printing solution of claim 10 , comprising 0.5 to 50 Vol.-% of radioactive printing solution and 50 to 99.5 Vol.-% ink.

14. A process for producing a radiation flood source comprising a flat substrate having printed on at least one surface thereof a radioactive coating comprising a radioactive material selected from at least one of an α-, β- and γ-emitting nuclide selected from the group consisting of Co-57, Ba-133, Gd-153, C-14, P-33, Te-99 and mixtures thereof, which coating provides for a homogeneous or controlled inhomogeneous radiation field, said process comprising:

homogeneously dissolving the radioactive material in a suitable solvent and mixing of the thus obtained solution with an ink or directly dissolving the radioactive material in an ink, optionally diluted with a suitable solvent, to obtain a radioactive printing solution,

printing this radioactive printing solution on the at least one surface of the substrate to provide the desired homogeneous or controlled inhomogeneous radioactive pattern by using an ink jet printer,

wherein the radioactive material is in form of a salt, complex or an organic compound comprising the same.

15. A process for producing a radiation flood source comprising a flat substrate having printed on at least one surface thereof a radioactive coating comprising a radioactive material selected from at least one of an α-, β- and γ-emitting nuclide selected from the group consisting of Co-57, Ba-133, Gd-153, C-14, P-33, Te-99 and mixtures thereof, which coating provides for a homogeneous or controlled inhomogeneous radiation field, said process comprising:

homogeneously dissolving the radioactive material in a suitable solvent and mixing of the thus obtained solution with an ink or directly dissolving the radioactive material in an ink, optionally diluted with a suitable solvent, to obtain a radioactive printing solution,

printing this radioactive printing solution on the at least one surface of the substrate to provide the desired homogeneous or controlled inhomogeneous radioactive pattern by using an ink jet printer,

wherein said solvent is a polar solvent selected from the group consisting of water, alcohols, ethers, esters, ketones, aldehydes and mixtures thereof.

16. A process for producing a radiation flood source comprising a flat substrate having printed on at least one surface thereof a radioactive coating comprising a radioactive material selected from at least one of an α- β- and γ-emitting nuclide selected from the group consisting of Co-57, Ba-133, Gd-153, C-14, P-33, Te-99 and mixtures thereof, which coating provides for a homogeneous or controlled inhomogeneous radiation field, said process comprising:

homogeneously dissolving the radioactive material in a suitable solvent and mixing of the thus obtained solution with an ink or directly dissolving the radioactive material in an ink, optionally diluted with a suitable solvent, to obtain radioactive printing solution,

printing this radioactive printing solution on the at least one surface of the substrate to provide the desired homogeneous or controlled inhomogeneous radioactive pattern by using an ink jet printer, and

drying the coating.

17. A process for producing a radiation flood source comprising a flat substrate having printed on at least one surface thereof a radioactive coating comprising a radioactive material selected from at least one of an α- β- and γ-emitting nuclide selected from the group consisting of Co-57, Ba-133, Gd-153, C-14, P-33, Te-99 and mixtures thereof, which coating provides for a homogeneous or controlled inhomogeneous radiation field, said process comprising:

homogeneously dissolving the radioactive material in a suitable solvent and mixing of the thus obtained solution with an ink or directly dissolving the radioactive material in an ink, optionally diluted with a suitable solvent, to obtain a radioactive printing solution,

printing this radioactive printing solution on the at least one surface of the substrate to provide the desired homogeneous or controlled inhomogeneous radioactive pattern by using an ink jet printer, and

cutting or punching out the substrate to the desired size and/or shape.

18. A process for producing a radiation flood source comprising a flat substrate having printed on at least one surface thereof a radioactive coating comprising a radioactive material selected from at least one of an α-, β- and γ-emitting nuclide selected from the group consisting of Co-57, Ba-133, Gd-153, C-14, P-33, Te-99 and mixtures thereof, which coating provides for a homogeneous or controlled inhomogeneous radiation field, said process comprising:

homogeneously dissolving the radioactive material in a suitable solvent and mixing of the thus obtained solution with an ink or directly dissolving the radioactive material in an ink, optionally diluted with a suitable solvent, to obtain a radioactive printing solution,

printing this radioactive printing solution on the at least one surface of the substrate to provide the desired homogeneous or controlled inhomogeneous radioactive pattern by using an ink jet printer,

wherein the substrate is a used radiation flood source and a second radioactive coating is primed thereon to re-increase radioactivity of the entire source for reuse.

19. A process for producing a radiation flood source comprising a flat substrate having printed on at least one surface thereof a radioactive coating comprising a radioactive material selected from at least one of an α-, β- and γ-emitting nuclide selected from the group consisting of Co-57, Ba-133, Gd-153, C-14, P-33, Te-99 and mixtures thereof, which coating provides for a homogeneous or controlled inhomogeneous radiation field, said process comprising:

homogeneously dissolving the radioactive material in a suitable solvent and mixing of the thus obtained solution with an ink or directly dissolving the radioactive material in an ink, optionally diluted with a suitable solvent, to obtain a radioactive printing solution,

printing this radioactive printing solution on the at least one surface of the substrate to provide the desired homogeneous or controlled inhomogeneous radioactive pattern by using an ink jet printer,

wherein after printing of the radioactive solution at least one protective coating is applied on at least part of the surface thereof.

20. The process of claim 19 , wherein the protective coating is provided before cutting or punching out the substrate.

21. The process of claim 19 , wherein the protective coating is provided by laminating a foil or sheet of the coating material.

22. The process of claim 19 , wherein the protective coating seals the substrate.