An improved non-local means regularized iterative reconstruction method for low-dose dental CBCT

In clinical practice, the widespread use of dental CBCT scanners has been limited because of cost, availability and radiation dose considerations. The recently proposed nonlocal means (NLM) method achieves excellent performance in digital image denoising, which can also be used in low-dose CBCT noise reduction. In this paper, we explore an improved non-local means (INLM) regularized iterative reconstruction method for low-dose CBCT with a low-mAs scanning protocol. By using a pre-classification and similar block searching method, the INLM filtering is more efficient than conventional NLM method. Clinical experiments have been conducted and demonstrate its performance in low-dose CBCT volume reconstruction. Compared with FDK method, the proposed method improves PSNR, image quality while preserves structure and detail information in low-dose CBCT imaging.