Breast cancer is the most common cancer type among women. Approximately one in every eight women is diagnosed with breast cancer at some time in their life and 30% to 40% of the women who get breast cancer die. Early and accurate detection is viewed as the best method to decrease breast cancer mortality. Therefore improving the accuracy and effectiveness of breast cancer detection has a vital value in improving women's health in US and worldwide. Mammography is an effective tool and currently widely used for early detection of breast cancer. It has played a substantial role in reducing the breast cancer mortality rate by over 20% in the last decade. However, limitations of mammography have been well publicized, such as very high false positive (70 - 90%) and false negative (-30%) rates. The problem arises from the difficulty in identifying cancerous mass and Mes due to overlapping breast tissues. Today's mammography techniques rely on a pair of 2-D X-ray images of the breast, taken from two different directions: top to bottom and side to side. The breast is pulled away from the body, compressed, and held between two glass plates to ensure that the whole breast is viewed. The images are then read by a radiologist. Breast cancer, which is denser than most healthy nearby breast tissue, appears as irregular white areas. Due to the 2-D imaging nature of mammography, breast cancer structures can be hidden in the overlapping tissue and not show up on the mammogram. Digital Breast Tomosynthesis (DBT) is a 3-D imaging technique which can overcome the tissue overlap problem. It takes multiple x-ray pictures of each breast from many angles. The breast is positioned the same way it is in a conventional mammogram. In all current commercial DBT scanners, the x-ray tube moves in an arc around the breast while 11 to 25 images are taken during an 8 to 40-second examination. Then the information is sent to a computer, where it is reconstructed to produce 3-D images of the breast. DBT has the potential to revolutionize mammography by significantly reducing the tissue overlap problem inherent in conventional 2-D mammography. In principle, DBT may lead to improved sensitivity and specificity, fewer recalls, fewer biopsies, lower false alarm rates, and reduced emotional impact, and DBT is expected to become a standard screening and diagnostic tool for breast cancer in the future.