A Phantom to Assess Quantitative Recovery of Positron Tomographs

Abstract

A simple phantom was employed to investigate the image linearity for a wide range of activity distributions and count rates. The phantom is composed of 2 activity regions, 1 contains a short-lived isotope and the other a long-lived isotope. Specifically, the phantom consists of a 20 cm flood phantom containing 68Ga (half-life 1.14 h) into which a 6 cm diameter cylinder containing 64Cu (half-life 12.7 h) is placed in an off-center position. The Cu region is initially a cold spot but, after many Ga half-lives, becomes a hot spot. Successive data sets from the phantom are taken over a long period and the reconstructed images analyzed to establish the linearity within each region and hence the stability against cross-talk from neighboring regions.