generator issues


Decay Characteristics
activity profiles
Activity Measurements
Safety Aspects

There are several types of generator design in current use. They all essentially are based on a system which traps the Rb81 and allows air to flow through the generator to sweep off the Kr81m gas produced from the decay of Rb81.

One system is based on a column of zirconium phosphate. Zirconium phosphate binds Rubidium and in a typical  system 300mgm of zirconium phosphate is trapped in a perspex column between two mylar frits.

The column is held in a lead shield assembly with two airline pathways, one for delivering an air flow and one for retrieving the Kr81m.  This lead shield has to be thick enough to cut down the external dose rate to a low level. The problem is not the 191kev gamma rays of Kr81m, which are easily shielded with only a few mm lead, but the higher energy gamma emissions of the Rb radionuclides.

The amounts of each Rb radionuclide depends on the production process. However approximately 5cm thick lead shielding has proved satisfactory for general use (however there may be a need for a secondary lead shield when used next to the gamma camera to avoid high background counts).





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Last modified: November 29, 2002