Targeting agents for enhancing radiation therapy

A method to combine high Z elements for delivery to a tumor in order to enhance the effect of ionizing x-ray radiation therapy, comprising:

• a. delivering an effective amount of a targeting agent to a diseased tissue wherein the targeting agent comprises a combination of heavy elements, each having an atomic number (Z) greater than 38 selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu and Ag, Sn, W, Re, Os, Ir, Au or Bi;
• b. wherein the targeting agent further comprises a ligand, a bone-targeting chelate, a soft tissue targeting chelate, a high payload targeting system, or a combination thereof to bind a high concentration of the heavy elements by functioning as an electron-pair donor in an electron-pair covalent bond formed with the heavy elements and selectively increasing the targeting agent in the diseased tissue;
• c. wherein neither the ligand, the bone-targeting chelate, the soft tissue targeting chelate nor the high payload targeting system is a biological carrier such as a protein, or a monoclonal antibody, or fragments thereof;
• d. wherein neither the heavy elements nor the targeting agent is radioactive-or becomes a radioactive isotope;
• e. administering external beam or brachytherapy ionizing x-ray radiation to interact with the greater cross-section of the heavy elements of the targeting agent in the diseased tissue;
• f. wherein the heavy element of the targeting agent enhances the diseased tissue's cross-section to ionizing x-ray radiation thereby creating additional ionizations and absorbed radiation dose.