Cone-beam x-ray microtomography of small specimens

Microtomography is a technique for creating three-dimensional images of the internal structure of objects with high spatial resolution. This can potentially allow inspection of the architecture of breast lumpectomy specimens and visualization of tumours in small animals and also has an application as a tool for non-destructive testing. An efficient method to perform microtomography is to use an area detector and cone-beam reconstruction techniques. In this paper we report on the development of an instrument for microtomography and show example images. The equipment consists of a microfocal x-ray tube (energies and currents up to 30 kVp, 0.2 mA, focal spot size < 5 microm), a rotating specimen stage and a high-resolution x-ray image intensifier optically coupled to a CCD video camera. Data acquisition and 3D image reconstruction are performed by a desktop computer. The well-known Feldkamp cone-beam reconstruction algorithm is used to produce tomographic images from the recorded x-ray projections. The instrument can image samples with diameters of 5-50 mm and create tomographic images with spatial resolution of the order 10-100 microm and signal-to-noise ratio of better than 5:1. This work is a continuation and improvement of an earlier instrument with a low-energy x-ray source and detector.