Correlation of Physical Parameters During Radiochemical Synthesis of 18F Positron Emission Tomography Radiopharmaceuticals

Positron emission tomography is a highly specialized imaging technique using short-lived radiolabel substances to produce extremely high resolution images of the body's biological function. The [sup]18F[sup]- ion is produced via the [sup]18O(p,n)[sup]18F reaction using a silver target cell filled with 1.4 mL of enriched [[sup]18O] water. On a typical run, the target is irradiated for 45 minutes with 16.5 MeV protons (on target) and an average beam current of 5-45 mA. When the same reaction takes place with [[sup]16O] water [[sup]13N] Ammonia is produced as the primary product by the abstraction of hydrogen from water. This study investigated the physical parameters of medical cyclotron during the radiochemical process with induced radioactivity flux and mutual correlation of physical parameters for 16.5 MeV medical cyclotron at the INMAS Delhi, India. It is observed that by getting farther from the target, the relative number of low-energy neutrons increases while the overall flux of neutrons decreases. This is due to multiple scattering of high-energy neutrons in the walls and eventually absorption of low-energy neutrons. The other parameters are also linked with each other which are correlatable.