Since several years there is an increasing number of hospitals using in diagnostics Positron Emitter Tomography (PET). This imaging method makes use of the detection of 2 coincident 511 keV gamma rays from positron annihilation. They were produced by the decay of positron emitters. The most important radionnuclides utilized in PET applications are shortlived isotopes like C-11, N-13, O-15 or F-18. These nuclides were generated in cyclotrons.


Radiation Protection in PET Centers

Radiation protection in PET centers requires the measurement of dose rate, of surface contamination and stack monitoring. Stack monitoring is especially important, because there are according to existing regulations limits for the release of activity concentration to the external environment. For instance in Germany, there is according to the new radiation protection ordinance a limit of 5000 Bq/m³ for the mean annual activity concentration of F-18 applicable. These limits are different in other countries. In many cases they are much higher.


Monitoring of Airborne Positron Emitters

Berthold provides extremely sensitive monitors for airborne positron emitters to meet the detection limits for Germany. The detection technology is based on large area proportional counter tubes. These are well-suited for the detection of positron particles. The detection of charged particles is much more localized than the detection of gamma rays. Thus the measurement of activity concentrations is much more precise, because the detectors view only into a well defined relatively small volume. If gamma detectors would be used, they can see activity from volumes even at large distances. This is dangerous, if activity concentrations are rapidly changing. There are several principal setups for the measurement of the exhaust-air at the cyclotron, at the hot cells or in the PET-room. Berthold provides careful planning, installation and calibration of the monitoring systems according to the special needs of the individual facility. We have excellent expertise in all regulational issues, technical questions and in customizing these monitors.