Uranium is present in nature as three isotopes — 238 U, 235 U and 234 U (99.28%, 0.73% and 0.005% abundance, respectively) — but these have very similar properties and are therefore difficult ...

This is done by choosing isotopes that: Positron emission tomography (PET) scans use a positron emitter as the contamination tracer. These tracer materials, such as fluorine-18, have very short ...