**6. Current directions in radiopharmaceutical research**

Nowadays, most of research in the area radiopharmaceutical is focusing on the tracers of receptor binding in biochemical reactions. The nature of these reactions may be Intra-extracellular in nature and may exhibit a good progress in tissue characterization using imaging technique in-vivo. Several of these agents are depending upon wide range of size; large MoAbs to tiny peptides (e.g. neuropeptide) which utilize bifunctional chelating agents to radiolabeling drugs/compounds. Radiopharmaceuticals of polypeptide may be in the brain whereas low molecular weight molecules retained high lipophilic characters to interact intercellular are highly needed (e.g. cell-surface receptors). Radiopharmaceutical chemists are facing many challenges to synthesis these compounds via one of two methods; namely integrated method or pendant method to utilize technetium coordination with interest on technetium (v) cores. Malignancy, neurology, inflammation, neurology, and infectious diseases are among many other health disorders which are in dire need of cytotoxic radionuclides in the area of radioimmunotherapy. This may prompt researchers to focus their research and the newly developed radiopharmaceuticals toward specific clinical and biological targets [9].
