1. Introduction
Lung cancer is the main reason for cancer-related mortality not only in the United States but also all over the world. Its rate increases despite the extraordinary evolution of the imaging devices and careful hospitalization, because it is usually diagnosed at late stages [1]. The early diagnosis of lung cancer will decrease the mortality rate by helping doctors decide the ideal way for lung cancer treatment for every patient [2]. The Computed Tomography (CT) scans increases the survival rate by 20% [3]. The problem that faces CT scans in the detection of lung cancer is that it is a very difficult task for doctors, as it takes much time to be analyzed because of the mass of the data that saved in the CT screening. A lot of researchers are beginning to develop new frameworks for computer aided diagnostic (CADx) systems to help doctors analyze this huge amount of data [4]. The new trend of this research depends mainly on merging image processing techniques and machine learning techniques to help in analyzing these huge amounts of data accurately and fastly to improve the cancer detection and diagnosis task [5].