Gamma detector can be relied on for PET quality checks

4 February 2009

Rapidly escalating demand for positron emission tomography as a medical imaging technique is putting PET centres and hospitals under increasing pressure to ensure the purity of the radiopharmaceuticals they manufacture and administer.

The need to check the quality of large amounts of gamma emitters every working day is beyond the capability of the beta counters that are sometimes pressed into service for this purpose; counting efficiencies are low and often unacceptable.

LabLogic Systems offers a highly dependable alternative - the Gamma-RAM radio-HPLC detector, which is designed specifically for soft and intermediate gamma emitters with energies up to around 1 MeV. One user who has had the detector for more than three years reports 100% trouble-free performance and no detectable loss of sensitivity.

Crucial to the Gamma-RAM's reliability are its heavy lead shield and its well-type titanium-activated sodium iodide crystal, which has greater stopping power for gammas. The high counting efficiencies that this achieves, even for more energetic isotopes, gives the superior resolution essential for PET radiopharmaceutical QC.

The Gamma-RAM has a hermetically sealed crystal/photomultiplier assembly, and both variable and fixed volume counting cells are offered for use with HPLC eluates.

The variable volume cell for low energy emitters consists of a Teflon tubing coil wound around a mandrel. The coil in turn is surrounded by a cylindrical tungsten sleeve that can be moved in or out with a micrometer, exposing more or less of the coil to the surrounding sodium iodide. Effective volumes from about 15 ul to 200 ul are possible.