Experimental evidences of 95 m Tc production in a nuclear reactor

The Chemical Scaffold of Theranostic Radiopharmaceuticals: Radionuclide, Bifunctional Chelator, and Pharmacokinetics Modifying Linker

Therapeutic radiopharmaceuticals have been researched extensively in the last decade as a result of the growing research interest in personalized medicine to improve diagnostic accuracy and intensify intensive therapy while limiting side effects. Radiometal-based drugs are of substantial interest because of their greater versatility for clinical translation compared to non-metal radionuclides. This paper comprehensively discusses various components commonly used as chemical scaffolds to build radiopharmaceutical agents, i.e., radionuclides, pharmacokinetic-modifying linkers, and chelators, whose characteristics are explained and can be used as a guide for the researcher.

Radioactive Transition Metals for Imaging and Therapy

Nuclear medicine is composed of two complementary areas, imaging and therapy. Positron emission tomography (PET) and single-photon imaging, including single-photon emission computed tomography (SPECT), comprise the imaging component of nuclear medicine. These areas are distinct in that they exploit different nuclear decay processes and also different imaging technologies. In PET, images are created from the 511 keV photons produced when the positron emitted by a radionuclide encounters an electron and is annihilated. In contrast, in single-photon imaging, images are created from the γ rays (and occasionally X-rays) directly emitted by the nucleus. Therapeutic nuclear medicine uses particulate radiation such as Auger or conversion electrons or β^- or α particles. All three of these technologies are linked by the requirement that the radionuclide must be attached to a suitable vector that can deliver it to its target. It is imperative that the radionuclide remain attached to the vector before it is delivered to its target as well as after it reaches its target or else the resulting image (or therapeutic outcome) will not reflect the biological process of interest. Radiochemistry is at the core of this process, and radiometals offer radiopharmaceutical chemists a tremendous range of options with which to accomplish these goals. They also offer a wide range of options in terms of radionuclide half-lives and emission properties, providing the ability to carefully match the decay properties with the desired outcome. This Review provides an overview of some of the ways this can be accomplished as well as several historical examples of some of the limitations of earlier metalloradiopharmaceuticals and the ways that new technologies, primarily related to radionuclide production, have provided solutions to these problems.