A phantom for 'mapping' slice thickness in X-ray computed tomography

The brief technical note describes an inexpensively produced slice thickness phantom (STP) made of low attenuation material, consisting of four sections of a large medium-density (933 kg m-3) polyethylene funnel arranged concentrically on a circular perspex baseplate. A single scan of it results in a ''map'' of slice thickness at representative points throughout the scan field. This has been used to investigate the slice geometry on an EMI CT5005 whole body scanner, equipped with a variable slice collimation facility, at Glasgow Royal Infirmary. (U.K.)