The rapid development of modern multi-slice computed tomography (MSCT) scanners has provided imaging systems with cone-beam geometry, sub-millimetre slice thickness, and gantry rotation speeds approaching 0.3 seconds per revolution. Clinical MSCT scanners routinely generate volume data sets yet the methods used to quantify spatial resolution remain relatively unchanged from those used to evaluate single slice scanners. In this paper, we describe a method for quantifying the spatial resolution of an MSCT scanner, with cone-beam, geometry using a sphere phantom. By scanning a Teflon sphere embedded in a uniform silicone cylinder, the plane spread function (PlSF) and modulation transfer function (MTF) may be determined. Furthermore, the spatial resolution in the axial and trans-axial directions may be independently quantified, as well as the effects of Azimuthal blur and spiral scanning. To illustrate the utility of the sphere method, the spatial resolution of two commercially available MSCT scanners was measured.
Recent advances in mouse genomics, including the production of transgenic mouse models, have created an interest in developing non-invasive imaging techniques for small-animal imaging applications. X-ray computed tomography (CT) can provide images with high-resolution isotropic voxels and low noise in relatively short acquisition times. In addition, CT provides volume data set, which allows the viewer to clearly visualize the spatial orientation of tissues within the mouse. We propose a model for an ideal, quantum-noise limited CT scanner for small-animal orientation of tissues within the mouse. We propose a model for an ideal, quantum- noise limited CT scanner for small-animal imaging with the objective of examining the fundamental limits of precision as a function of resolution and dose to the animal. The variance was calculated for several doses and voxel sizes to determine the precision in the linear attenuation coefficient values for the idealized small-animal volume CT scanner. For whole-body exposure of 1.5 Gy, our study predicts precision of +/- 5.8 percent in linear attenuation coefficient, with (0.1 mm)3 isotopic voxels. This work shows the effect of photon noise on the precision that can be expected for micro-computed tomography of small animals in vivo for a given isotopic voxel size and x-ray dose to the animal. The predictions of this work ca be used to design novel imaging systems for use in small-animal research.