A feasibility study of data redundancy based on-line geometric calibration without dedicated phantom on Varian OBI CBCT system

As the conventional method of geometric calibration not only needs extra-scan but also have the vulnerability to the dimensional accuracy of the dedicated phantom, we proposed a new geometric calibration scheme based on data redundancy which uses projection data of any arbitrary patient already scanned, mainly focused on a geometry of Varian’s OBI system. Using the fan-beam based data redundancy which can be applied to cone-beam projection data of either full-fan or half-fan geometry, one could successfully detect the misalignments of geometric parameters and find the values of them. The simulation studies using the XCAT numerical phantom were conducted to check the feasibility of data-redundancy-based method can detect the misalignment of geometric parameters and find true values.