TECHNEGAS - A STUDY OF PARTICLE STRUCTURE, SIZE AND DISTRIBUTION

Technegas (TcG) was produced using a commercially available TcG genera tor. The structure and size distribution of TcG particles were examine d by means of the following methods: (a) transmission electron microsc opy (TEM), range: 1 nm-100 mum; (b) time-of-flight mass spectroscopy ( MS), range: < 3 nm; (c) photon correlation spectroscopy (PCS), range: 3 nm-3 mum. The TEM images showed graphite particles (size 7-23 nm) ag glomerated into larger secondary aggregates. The size of these aggrega tes, determined from PCS and TEM measurements, showed a log-normal dis tribution and typically ranged from 60 to 160 nm. No isolated particle s smaller than 3 nm could be detected by MS. We conclude that TcG part icles consist of technetium-99m labelled agglomerated graphite particl es and have an average size of 97 nm (geometrice standard deviation (G SD): 1.55).