CT image denoising using NLM and its method noise thresholding

Computed Tomography (CT) is one of the major tools to identify diagnose in medical science. The quality of CT images is dependent of X-ray amount. If X-ray dose is higher, the quality of CT image is better but it may generate bed impact to the patients. Low dose CT images are noisy due to some major reasons such as statistical uncertainty in all physical measurements. If noise can be reduced or removed from low dose CT images, then quality of low dose CT images can be improved without increasing dose. Hence in this paper, a method is proposed in which Non-local means (NLM) filter and wavelet packet based thresholding are processed. For better edge preservation and noise reduction, method noise concept is used. The results of proposed method is analyzed and also compared with some existing methods. From comparative result analysis, it was observed that performance of the proposed scheme is superior to the existing methods in terms of visual quality, Image Quality Index (IQI), PSNR and Entropy Difference (ED).