High-Quality 4D-CBCT Imaging from Single Routine Scan

Abstract

AbstractThe 4D-CBCT imaging from single routine scan can be used to address the respiratory-induced artifacts in image-guided radiation therapy. The sparse projections in each breathing phase degrade the image quality of 4D-CBCT. In radiotherapy, the CBCT scans are usually performed in multi-factions, which could be applied as the prior information to improve the image quality of 4D-CBCT images. We propose a novel method to obtain high-quality 4D-CBCT images from a routine scan in patients by utilizing multi-fraction projections. The multi-fraction projections are sorted according to the location of the lung diaphragm before being reconstructed to phase-sorted data. Oriented subsets simultaneous algebraic reconstruction technique (OS-SART) algorithm is used to reconstruct the intermediate phase-sorted data. The multi-phase and multi-fraction intermediate CBCT images are further used to estimate the deformable vector field (DVF) among breathing phases and fractions using the deformable image registration method. We propose a motion-compensated OS-SART approach to compensate the motion error among different breathing phases and fractions in the iterative reconstruction process. Results show that our method using multi-fraction projections significantly outperforms single-fraction based method in lung cancer patient studies. The proposed method enables a practical way for high-quality 4D-CBCT imaging from a single routine scan by using multi-fraction projections as prior.Keywords4D cone beam CTMulti-fraction projectionsMotion compensationOriented subsets simultaneous algebraic reconstruction technique (OS-SART)