I-124 production using nanomaterials and its biodistribution in animals

Iodine-124 is a positron emitter with physical half-life of 4.2 days. Its decay occurs by positron emission (23.3%) and electron capture (76.7%). Their physical and chemical characteristics make it an attractive isotope for medical applications. The development of new imaging techniques, improvements in Positron Emission Tomography (PET), the development of new detectors and computational methods of signal processing, open new perspectives for its application. The increasing use of PET technology in medical oncology, pharmacokinetics and drug metabolism, make the radiopharmaceuticals labeled with ¹²⁴I a tool of great interest and usefulness. The use of ¹²⁴I - labeled molecules stands out particularly due to the convenient half-life of ¹²⁴I. This feature enables diagnostic imaging in PET centers far away from the radionuclides producing center. Within this context, this work presents a method for the production and separation of ¹²⁴I. This method is innovative and pioneering in the country. It is based on the development and use of nanostructured targets of ^natTeO₂. These targets are irradiated in a charged particles accelerator, with variable energy, the IEN's CV-28 cyclotron. The irradiations are performed with 24 MeV, initial energy, proton beams. In the preparation of nanoparticulated targets the highlight was the simplicity of the method that uses the sol-gel technique for obtaining nanoparticles, TeCl₄ as precursor and water as solvent. The produced ¹²⁴I was separated from the target material by dry distillation and trapped in a NaOH solution (0.02 M), in an automated system. The thick target yield was 6.81 MBq/μAh, and the synthesis yield was 90%. The ¹²⁴I obtained was then used in preliminary biodistribution studies. These studies were performed on a micro PET, model Lab PET 4 of the CDTN, in Swiss type mice. The results of the application of Na¹²⁴I showed high quality PET imaging of the thyroid, with the maximum uptake at 6 h after injection. (author)