In general a CT scan is much better at finding lung cancers than a chest Xray (see here, here, and here also see T stage and node stage) see collage of images here

Chest Xrays:  small right upper lung nodule ,Xray of large right lung cancer  Xray of small left lung cancer,   Xray of lung metastases,  Xray large right lung cancer

CT Scans:  chest Xray versus CT, chest Xray versus CT,   Xray versus CT, CT small left lung nodule,  CT Node Mets,  CT node spread, cavitary lung cancer,   CT small cell before and after therapy here

CT large left lung cancer , CT another large left lung cancer, CT mediastinal nodes, benign lung nodule , large mediastinal mass, CT large hilar mass,  brochoalveolar #1,  brochoalveolar #2,  mesothelioma, Pancoast tumor#1 and # 2.  

CT trachea destruction

Benign tumors can look like cancer on a CT (see goiter).

PET scans: are even better than CT scans at identifying lung cancers, go here