Registration between MVCT reconstructed from EPID and kVCT

Abstract

The registration of two-dimensional MV electronic portal imaging device (EPID) images and digital reconstruction radiograph (DRR) images has been widely used for the setup error correction of radiotherapy, the approaches estimate the 3D transformation is not very accurate. The purpose of this paper is to verify the feasibility of a new setup error estimation method that registers 3D planning CT image and 3D image that is reconstructed based on EPID. EPID images were acquired and used to reconstruct the MVCT by Algebraic Reconstruction Technique (ART) algorithm. The reconstructed image and the planning CT were registered by maximizing the mutual information (MI) between two 3D images. The registration error is less than 3mm, which is suitable for clinical implementation. The study demonstrated that the 3D/3D registration method proposed for the setup error correction of radiotherapy is feasible.