Zoom-in micro tomography with the combination of full and limited field-of-view projection data

In this paper, we introduce an X-ray microtomography system capable of high-resolution zoom-in imaging of a local region inside a large object. By combining two kinds of projection data, one from the full field-of-view (FOV) scan of the whole object and the other from the limited FOV scan of the region of interest, we have obtained zoomed-in images of the region of interest. With computer simulations, we have found that the proposed zoom-in imaging technique has superb spatial resolution, comparable to that of local tomography, without any contrast anomalies commonly appearing in conventional local tomography. To verify the zoom-in imaging capability experimentally, we have integrated a micro tomography system using a micro-focus X-ray source, a flat-panel CMOS X-ray detector with the matrix size of 1248times1248, and a precision scan mechanism. The mismatches between the two projection data caused by misalignments of the scan mechanism have been estimated with a calibration phantom and the mismatch effects have been compensated in the image reconstruction procedure. Zoom-in imaging results of bony tissues with the spatial resolution of 20 mum suggest that zoom-in microtomography can be greatly used for high resolution imaging of a local region in small animal imaging studies