2D simulations of an inverse-geometry volumetric CT system with multiple detector arrays

摘要

The performance of an inverse geometry volumetric CT (IGCT) system with multiple detector arrays is beinginvestigated. The system is capable of a complete acquisition of a volume free from cone-beam artifacts withonly a single rotation of the gantry. The IGCT system is composed of a large source array opposite three smalldetector arrays with a field-of-view (FOV) large enough for clinical imaging (45cm). Simulations were conductedto estimate the MTF at different points in the FOV. The simulations involved generating 2D projection data of a100um circular object followed by a reconstruction algorithm that uses gridding and filtered backprojection. Thesimulations also modeled finite source spot and detector element sizes. The estimated MTF’s were comparedwith theoretical MTF’s at 0 cm, 10 cm, and 20 cm away from the isocenter. The simulated MTF’s closelymatched the theoretical MTF’s. The MTF in the radial direction was over 10% at 16 lp/cm across the entireFOV while the azimuthal MTF 10% point degraded to 10.4 lp/cm at the edge of the FOV. This degradationin azimuth, which can be corrected for, is due to gridding in the angular direction which is magnified at largedistances away from the isocenter. The simulations show promising results for the in-plane resolution of themultiple detector array IGCT system. Noise properties and other factors impacting performance are currentlybeing investigated.