The move from 2D to 3D analysis, and the increase in spatial resolution cha
racterize recent improvements in CT-based structure assessment. A new deskt
op micro-CT system with high scanning speed has been developed. The instrum
ent makes use of a novel multiple fan-beam technique: radiation from a line
-focus X-ray tube is divided into a stack of fan-beams by a foil collimator
with a 30 mu m pitch. The stacked fan-beam geometry allows to design compa
ct CT scanners with a source-to-detector distance of only 18 cm. The comple
te system fits into a standard 19 in. rack. Image reconstruction is based o
n standard fan-beam algorithms, which eliminates the difficulties and limit
ations associated with cone-beam reconstruction. The detector comprises a l
ow-noise area CCD sensor, a fiber-optic light guide and a scintillator scre
en. A complete examination requires 2 min only. The new micro-CT system has
a voxel size of 20 x 20 x 26 mu m(3). Each 3D image contains a quarter of
a billion voxels or a multiple of it. Samples up to 20 mm in diameter and u
p to 40 mm in length can be imaged. The instrument can be operated in a nor
mal lab environment. (C) 2000 Elsevier Science B.V. All rights reserved.