Low-dose CT image restoration using a non-local weights prior from previous normal-dose scan image

A novel approach is proposed to improve low-dose CT image quality by a non-local weighs prior which is acquired from previous normal-dose scan. First, we align two images-the low-dose and the previous normal-dose scan image, and filter the low-dose image to suppress noise. Then, the weight matrix of the registered normal-dose image is calculated by the non-local means weighting formula, and the low-dose image is restorated using this weight matrix as a prior. Simulated phantom and perfusion data experiment results demonstrate a highly quality improvement in terms of suppressing noise-induced streak artifacts and preserving resolution of the low-dose image using the proposed method. The proposed method is especially effective for clinical short-term repeated CT scan, such as perfusion and radiation therapy.