Improved small scale production of iodine-124 for radiolabeling and clinical applications.

Aim: This work describes a small-scale production of iodine-124 using a 16.5 MeV cyclotron, and a subsequent validation of the formulated sodium [124I]iodide solution for routinely clinical applications.
Methods: Iodine-124 ( ¹²⁴ I) was produced via the ¹²⁴ Te(p, n) ¹²⁴ I reaction using a 16.5 MeV GE PETtrace® cyclotron. Irradiation was performed with a pre-prepared solid target consisting of [ ¹²⁴ Te]TeO ₂ (99.93%) and Al ₂ O ₃ . Different layer thicknesses, irradiation and extraction parameters were tested. After irradiation at the cyclotron, the shuttle with irradiated material was transferred fully automatically via a tube system to the Comecer ALCEO ^® Halogen 2.0 extraction unit. Iodine-124 was subsequently extracted in form of sodium [ ¹²⁴ I]iodide ([ ¹²⁴ I]NaI) in 0.05 N aqueous NaOH solution, followed by reconstitution and validation for preclinical and clinical uses.
Results: Good result was achieved using a beam degradation foil of 500 µm thickness in combination with beam currents between 10 and 15 µA. Under these conditions, up to 150 MBq no-carrier-added [ ¹²⁴ I]NaI was obtained after a 2 h irradiation time in less than 500 µl 0.05 N NaOH. Isolation of [ ¹²⁴ I]NaI, including evaporation and extraction at the ALCEO ^® Halogen EVP unit was accomplished in 90 min 24 h after production (irradiation), the amount of iodine-123 as assessed by gamma-ray spectroscopy was less than 1.5%. The undesirable iodine-125 was not detectable by gamma spectroscopy. The extracted [ ¹²⁴ I]NaI could be used directly for radiolabeling purposes, and after buffering with phosphate buffered saline (PBS) and sterile filtration for clinical applications.
Conclusions: Through the optimized conditions for irradiation and extraction, iodine-124 was produced in good radiochemical yields and high radionuclide purity. The generated injectable [ ¹²⁴ I]NaI solution was sterile, non-pyrogenic and ready for preclinical and clinical applications after a sterile filtration through a 0.22 µm membrane filter.
(Copyright © 2018 Elsevier Ltd. All rights reserved.)