Standardization of 18F using the 4π(β+γ) integral counting technique

Α 4π(β+γ) integral counting technique using a 4πβ−4πγ detector configuration was adopted for the standardization of 18F. In this technique, the β-detector is composed of two thin plastic scintillators sandwiching the source, coupled with a slender photomultiplier tube. The β-detector part with the source was inserted into a large well-type NaI(Tl) scintillation detector for γ-ray detection, making a 4πβ−4πγ coincidence counting system. In this work, positron particles were detected with high efficiency in the β-channel and annihilation quanta were also detected with high efficiency in the 4πγ channel. The very small inefficiency of the 4π(β+γ) integral counter for the β-plus branch has been confirmed by EGS5 Monte Carlo simulation. The result using this technique agreed within the uncertainties with the result obtained by the conventional 4πβ−γ coincidence counting with the efficiency extrapolation technique using the same detector configuration and a conventional 4πβ−γ coincidence counter.