Design and use of mini-phantoms for high resolution planar gamma cameras

There is now wide spread interest in the application of small field of view gamma cameras for clinical use in operating theatres, intensive care units and bedside imaging. The development of these imaging systems some of which have improved spatial resolution has necessitated a reappraisal of the suitability of conventional phantoms intended for use with gamma cameras. The testing of imagers having increased system resolution requires phantoms and test objects of smaller dimensions. We have investigated the use of high resolution mini-phantoms for the evaluation of planar imaging devices with spatial resolution of the order of 1 mm. We present images of a number of phantoms that show their suitability for evaluating high resolution planar gamma cameras. It is also apparent that there are a number of practical difficulties that have not been previously reported when using liquid filled phantoms with hole sizes between 1 and 4 mm. In particular problems of filling small diameter holes and liquid surface tension effects can limit the utility of these phantoms. Initial observations when imaging mini-phantoms with a high resolution CCD based gamma camera are presented.