Deep learning based denoising techniques have effectively reduced noise in low-dose computed tomography (LDCT) images. However, the need for pairs of LDCT and normal-dose CT (NDCT) training images is the main reason that makes the use of deep learning networks difficult. Therefore, we propose a method of generating synthesized LDCT images by adding synthesized quantum noise to the NDCT images. For this, we estimate the quantum noise power spectrum (NPS) of patient CT images by modeling anatomical NPS and quantum NPS, respectively. We use the quantum NPS as a noise filter and generate synthesized quantum noise by filtering random Gaussian noise. Using the proposed method, LDCT denoiser can be trained without using pairs of LDCT and NDCT images, and the trained denoiser effectively reduces noise in LDCT images. The proposed method facilitates data acquisition for training deep learning networks and reduces the risk of radiation exposure to patients.
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