Enhancing 18F uptake in a single particle for positron emission particle tracking through modification of solid surface chemistry

Abstract

The positron emission particle tracking (PEPT) technique has been widely used in science and engineering to obtain detailed information on particulate motion in granular materials and flow fields in multiphase systems. The technique involves tracking a single radioactively labelled particle by detecting the pairs of back-to-back 511 keV γ-rays arising from annihilation of emitted positrons. It is thus crucially dependent on the availability of suitably labelled tracer particles. With the present equipment, the optimum activity for a PEPT tracer is between 300 and 1000 μCi. The positron emitting radionuclide most often used is 18F in the form of fluoride ions. However, most materials have a very poor capacity to take up fluoride naturally. This paper presents a surface modification technique which was developed to improve the adsorption of 18F on solids and therefore extending the application of PEPT. For example, 200 μm MCC particles are the subject of many PEPT studies, but these particles only adsorb a few μCi 18F naturally, and cannot be used as tracers for PEPT. After surface modification, they take up about 700 μCi 18F, and can be tracked very well using PEPT.