Activity determination of 68 Ge/ 68 Ga by means of 4πβ(Č)-γ coincidence counting.

Germanium-68 is an important radionuclide since it is used to generate its daughter 68Ga which is frequently used for positron emission tomography (PET). In addition, 68Ge/68Ga sources are often used as surrogates for short-lived PET isotopes when calibrating instruments. In this work, 4πβ(Č)-γ coincidence counting was used to determine the activity concentration of a 68Ge/68Ga solution. The presented measurements were made by means of a new PTB-custom-built 4π(LS)β-γ coincidence counting system, where a liquid scintillation detector in the β channel can also be used as a Čerenkov counter, and a NaI(Tl) crystal detects annihilation radiation.