Small Animal X-ray Micro-CT with Zoom-in Imaging Capability

Most of micro-CTs are capable of micron-resolution imaging if a small sample is of interest. Recent micro-CT developments with a flat-panel detector make it possible to scan the whole body of a small animal as large as a medium sized rat. However, the spatial resolution in the whole body imaging should be sacrificed down to the order of 100 mum due to the limitation in the number of X-ray detector pixels and low signal-to-noise ratio. In this study, we introduce an X-ray zoom-in micro tomography system which has localized imaging capability, i.e., high resolution imaging of a local ROI inside a large subject, for small animal imaging studies. In zoom-in micro tomography, two projection data sets, one obtained with a full FOV scan and the other obtained with a limited FOV scan, are acquired with different magnification ratios. To obtain exact images of the ROI, the out-of-FOV projection data are calculated from the full FOV projection data, and then, the calculated projection data are augmented to the limited FOV projection data. The zoom-in micro tomography system consists of a micro focus X-ray source, a CMOS flat-panel detector, a rotating gantry and a parallel data processing system. We have used the zoom-in micro tomography system for in vivo femoral bone imaging in osteoporosis studies with SD rat models in which fine trabecular bone structure imaging is essential.