Patent Number: 
Section: claims

1. A radiation shield comprising a radiation attenuating layer, comprising:a first sublayer comprising a first radiation attenuating material comprising a salt of a first elemental species having a first atomic number; anda second sublayer comprising a second radiation attenuating material comprising a salt of a second elemental species having a second atomic number, the second atomic number being higher than the first atomic number;wherein the radiation attenuating material of the first sublayer differs from the radiation attenuating material of the second sublayer, and wherein all the radiation attenuating materials in the radiation attenuating layer are salts of an elemental species. 2. The radiation shield of claim 1, wherein the first sublayer is configured to attenuate incident ionizing radiation emanating from a source of ionizing radiation, and the second sublayer is configured to attenuate secondary ionizing radiation emanating from the first sublayer. 3. The radiation shield of claim 1, wherein the first sublayer is configured to attenuate a first range of energies of ionizing radiation, and the second sublayer is configured to attenuate a second range of energies of ionizing radiation. 4. The radiation shield of claim 3, wherein the first range of energies of ionizing radiation are higher in energy than the second range of energies of ionizing radiation. 5. The radiation shield of claim 1, wherein the first radiation attenuating material is configured to attenuate ionizing radiation over a first bandwidth of frequencies or wavelengths, the second radiation attenuating material is configured to attenuate ionizing radiation over a second bandwidth of frequencies or wavelengths, and the first bandwidth and the second bandwidth differ from one another. 6. The radiation shield of claim 1, wherein the first sublayer comprises one of the following: barium species, bismuth species, and lanthanum species. 7. The radiation shield of claim 1, wherein the first sublayer comprises barium sulfate and the second sublayer comprises bismuth oxide. 8. The radiation shield of claim 1, wherein all the radiation attenuating materials in the radiation attenuating layer are salts of an elemental species having an atomic number of 50 or greater. 9. The radiation shield of claim 8, wherein all the radiation attenuating materials in the radiation attenuating layer are salts of an elemental species having an atomic number of 56 or greater. 10. The radiation shield of claim 1, wherein the first sublayer is configured to be positioned closer to a source of ionizing radiation than the second sublayer. 11. A radiation shield comprising a radiation attenuating layer, comprising:a first sublayer comprising a first radiation attenuating material comprising a salt of a first elemental species having a first atomic number; anda second sublayer comprising a second radiation attenuating material comprising a salt of a second elemental species having a second atomic number, the second atomic number being higher than the first atomic number;wherein the first sublayer is configured to attenuate a first range of energies of ionizing radiation and the second sublayer is configured to attenuate a second range of energies of ionizing radiation, and wherein all the radiation attenuating materials in the radiation attenuating layer are salts of an elemental species. 12. The radiation shield of claim 11, wherein the first sublayer is configured to attenuate incident ionizing radiation emanating from a source of ionizing radiation, and the second sublayer is configured to attenuate secondary ionizing radiation emanating from the first sublayer. 13. The radiation shield of claim 11, wherein the first range of energies of ionizing radiation are higher in energy than the second range of energies of ionizing radiation. 14. The radiation shield of claim 11, wherein the first sublayer comprises barium sulfate and the second sublayer comprises bismuth oxide. 15. The radiation shield of claim 11, wherein all the radiation attenuating materials in the radiation attenuating layer are salts of an elemental species having an atomic number of 50 or greater. 16. The radiation shield of claim 11, wherein the first sublayer is configured to be positioned closer to a source of ionizing radiation than the second sublayer. 17. The radiation shield of claim 11, wherein the radiation attenuating material of the first sublayer differs from the radiation attenuating material of the second sublayer. 18. A method for attenuating ionizing radiation, comprising:positioning a radiation shield between a source of ionizing radiation and a subject to be shielded from the ionizing radiation, the radiation shield comprising a radiation attenuating layer, comprising:a first sublayer comprising a first radiation attenuating material comprising a salt of a first elemental species having a first atomic number; anda second sublayer comprising a second radiation attenuating material comprising a salt of a second elemental species having a second atomic number, the second atomic number being higher than the first atomic number;wherein the first sublayer is configured to attenuate incident ionizing radiation emanating from the source of ionizing radiation, and the second sublayer is configured to attenuate secondary ionizing radiation emanating from the first sublayer, and wherein all the radiation attenuating materials in the radiation attenuating layer are salts of an elemental species; andorienting the radiation shield such that the first sublayer is closer to the source of ionizing radiation than the second sublayer. 19. The method of claim 18, wherein the first sublayer comprises barium sulfate and the second sublayer comprises bismuth oxide. 20. The method of claim 18, wherein the radiation attenuating material of the first sublayer differs from the radiation attenuating material of the second sublayer.