Radiopharmaceutical Production

1. Radiopharmaceutical Production Sub STOP

2. Radionuclidic purity • Radionuclidic purity may be defined as the fraction of total radioactivity that is present as the specified radionuclide. • Radionuclidic impurities may also be other radioisotopes of the same element or some other radionuclides generated in the target from target materials, foils or target bodies. The nature and levels of radionuclidic impurities depend on the type of nuclear reaction, target bodies and foils used in the target. Contents • Requirements • Procedure

3. Requirements Requirement: Greater than 99.5% of the gamma emissions observed in the γ-ray spectrum of the test sample obtained with suitable γ-ray spectrometer should correspond to the 511 KeV, 1022 KeV sum peak and/or Compton scatter peaks of 18F. Discussion: The gamma spectrum of[18F]FDG should have only 511 KeV and/or 1022 KeV sum peak. It must, however, be realized that the mere presence of 511 KeV or 1022 KeV peak in the γ-ray spectrum is not sufficient to determine radionuclidic purity. Positron emitting impurities such as N-13 (arising from O-16 water in the target) will have the same gamma spectrum as F-18. Therefore, γ-ray spectrum exhibiting the presence of 511 KeV and/or 1022 KeV sum peak, along with the half-life data should be used for confirmation of radionuclidic identity. Frequency of test

4. Gamma Spectrum Procedure A small aliquot of the final FDG solution should be placed in a suitable sample holder. This sample should be analyzed using a standard gamma spectrometer The sample of FDG should be allowed to decay for at least 10 half-lives and then another gamma spectrum taken to ensure there are no long-lived activities present in the sample This test may be repeated yearly if no changes in the synthesis or equipment is made. If changes are made, the test should be repeated to ensure adequate radionuclidic purity. Demonstration

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