Abstract

Positron emission tomography (PET) is a medical imaging technique that relies upon the synthesis of radioactive chemicals that produce gamma rays as they decay. The most commonly used radiochemical in PET is [¹⁸F] 2- fluoro-2-deoxy-D-glucose (FDG). The current method of synthesis of FDG results in a 10%-25% loss of the radioisotope. Because the reaction is carried out in a sealed synthesis chamber for safety reasons, the only means of monitoring the process is via a remote system. Therefore, a need exists for a monitoring system that would provide data to determine at which step the loss occurs during the synthesis, while maintaining radiation safety standards. In this project, positive-intrinsic-negative (PIN) diodes were used as detectors to remotely monitor the synthesis of FDG in order to gain infonnation that would enable the yield to be improved. After a series of characterization tests, the diodes were set in place and several FDG syntheses were monitored. Analysis of the data revealed the exact step in the synthesis at which the loss of the radioisotope, ¹⁸F, occurred.