As part of its ongoing support to the National Measurement System in t
he UK, the National Physical Laboratory (NPL) conducted two intercompa
rison exercises in 1996. The participants, hospital physicists, were r
equired to assay samples of Ga-67 and I-123 using radionuclide calibra
tors. The analysis of the results presented here, whilst encouraging i
n terms of overall level of quality compared with previous exercises,
identified several areas of concern. The results are discussed, conclu
sions drawn and recommendations made. (C) 1998 The National Physics La
boratory. Published by Elsevier Science Ltd. All rights reserved.