Induced activities during the production of [18F]FDG using a GE PETtrace cyclotron

Abstract

1907

Objectives: (1)To measure the levels of proton and neutron induced activation products within the accelerator and shielding components of a GE PETtrace medical cyclotron used for the production of 18F- (2)To determine the presence of activation products in irradiated 18O-enriched water, examine their distribution in the different components of a [18F]FDG synthesis unit, and evaluate the radiochemical purity of the [18F]FDG.

Methods: The GE Medical System PETtrace cyclotron used at M2i in Dublin commenced production of 18F-fludeoxyglucose under Good Manufacturing Practice (GMP) conditions in October 2001. To date, the cyclotron has been exclusively used for the production of 18F- via the 18O(p,n)18F reaction with 16.5 MeV protons. In this paper, we report the levels of proton and neutron induced activation products in the accelerator and supporting subsystems, including various components of the targetry system. The levels of radioactive impurities in irradiated 18O-enriched water, resins and waste solutions from the [18F]FDG synthesis unit and the purified [18F]FDG solution are also reported. Activities have been determined using a combination of gamma, X-ray and beta spectrometry.

Results: Radionuclides identified in different components of the accelerator included 51Cr, 52Mn, 54Mn, 55Fe, 56Co, 57Co, 58Co, 95Tc, 109Cd, 183Re and 184Re, with by far the highest activities (in the MBq range) found in the foils and collimators of the target assembly. Activation products induced in the havar foils were also found to be present in the irradiated 18O-enriched water, with activities ranging between 6 Bq/ml and 2.5 kBq/ml. None of these activation products were detected in the purified [18F]FDG solution.

Conclusions: The results of the present study show that a range of radioisotopes are generated within the target assembly, collimators, separation foils, shielding components and irradiated 18O-enriched water. Provided that good radiation safety work practices are followed, the measured levels do not represent a significant radiological hazard for cyclotron operating staff or personnel operating in the clean room environment where the radiopharmaceutical is synthesised.