Participants in the 1996 International In Vivo Intercomparison Programme

The Human Monitoring Laboratory (HML) and the United States Department of Energy (USDOE) collaborated again to offer an international intercomparison programme to whole body counting facilities in 1996. The Human Monitoring Laboratory (HML) fabricated a phantom shell corresponding to a reference female and Battelle Pacific Northwest National Laboratory (BPNNL) filled the shell with radioactive tissue-substitute polyurethane to simulate a uniform fission-product distribution in soft tissues.

The amounts of the radionuclides on 08-May-96, 1200 Pacific Standard Time (PST) were:

• ⁴⁰K: 2.99± 0.15 kBq
• ⁶⁰Co: 19.89 ± 0.19 kBq
• ¹³⁷Cs: 20.05 ± 0.50 kBq

Each facility was asked to determine the identity and amount to the radionuclides in the energy range 200 - 2000 keV (disregarding 40K). Each facility was asked to estimate precision without changing the phantom's position and estimate their minimum detectable activity. The programme had participants from 23 countries for a total of 63 counting systems.

The programme began in June 1996 and ended on 24-March-1999, when the phantom arrived back at the NCRC from the last participant's laboratory.

The results of the intercomparison showed that:

• bias results were in the range of -30% to +80% with most facilities falling inside the range of -25% to +50% (Canadian and US acceptable performance criteria)
• there was no measurable size dependency for the female phantom
• all reported percussion were less than 5% but an systems seemed to have a systematic uncertainty
• minimum detectable activity (MDA) results were quite variable and only suggested that lengthening the counting time improved the MDA