X-ray projection microscopy and cone-beam microtomography

A laboratory sized X-ray projection microscope and microtomographic imaging system is being developed at SUNYAB (AMIL-ARTS). High resolution two dimensional images can be recorded rapidly using a high resolution phosphor and a cooled slow scan CCD camera. The effective source size is kept small to maximize the resolution. For this purpose, the electron beam is focused onto a thin film target. Three dimensional information can be derived from the high resolution two dimensional images by generating stereo pairs or by reconstructing the complete tomographic image. Real time stereo pairs can be produced by rapidly moving the position of the electron spot between two locations on the thin film target, thus irradiating the specimen with X-rays from two spatially distinct directions. For high resolution tomography, or microtomography, the two dimensional images are recorded for a large number of different orientations of the specimen. A cone beam reconstruction scheme based on a convolution and back projection algorithm is being developed. To optimize the experimental parameters in microtomography, a variety of mathematical phantoms have been examined using computer simulation technique. The experimental results reveal the quantitative relationship between the accuracy of the reconstructed image and the experimental parameters such as object shape, orientation and position.