De-noising low dose CT images of the ovarian region using modified discrete wavelet transform.

Computed Tomography (CT) is a medical imaging technique that is being prominently used in the healthcare domain to obtain a detailed view of the body for diagnostic purposes of various diseases. This form of medical imaging is associated with high ionizing radiations that are powerful enough to penetrate through the body to create images on the computer screen. But, multiple exposures to such high dose ionizing radiation could raise the chances of cancer and could be fatal for patients diagnosed with cancer. However, to reduce the radiation dosage associated with CT images, low-dose CT (LDCT) is being used for medical screening in recent days. The United States Preventive Services Task Force guidelines has revealed that LDCT screening reduces the mortality rate of patients and can be considered safe comparatively. But, as radiation dosage is reduced, LDCT images are corrupted with noise and artifacts which affect the visibility of the medical image. This in turn can affect the decision of the radiologists. Therefore, LDCT images are required to be de-noised before being used for diagnosis to improve the image quality and elevate visibility. This work is one such method where a combination of modified Discrete Wavelet Transform (DWT) and Goodness of Fit shrinkage (GoFShrink) thresholding technique is used to denoise the LDCT images to enhance the quality for diagnostic purposes. The modified DWT is associated with a lifting scheme that provides memory for in-place arithmetic operations, flexible factorization of the 2-channel filter banks as well as robustness with exact reversible reconstruction and enhances the performance of the wavelet transform (WT). The PSNR, MSE, SSIM, and SNR values of the de-noised images are calculated and a comparative analysis is performed with the conventional de-noising techniques. A comparative analysis between the various shrinkage techniques is also performed. The simulation results show an increase in PSNR and SNR values when compared with the conventional methods. [ABSTRACT FROM AUTHOR]