Optimal screening tool for thoracic diseases: chest X ray or CT?

There are good reasons to believe that screening of lung parenchymal diseas es by CT is superior to chest radiographs. Nevertheless, conventional chest radiography often remains the first examination performed for evaluation o f thoracic diseases and, irrespective of clinical indication, it plays an i mportant role in screening procedures, The interpretation methodology of a chest radiograph in a screening condition is reviewed. Specific attention t o poor detectability zones is emphasized and a check-list is proposed, main ly to reduce the risk of overlooking lesions, Techniques, indications and r espective diagnostic values for both chest radiography and CT scan are anal yzed and applied to the screening of lung cancer, asbestos exposure and tub erculosis.