Lung cancer is the leading cause of cancer-related death around the world, it represents 13% of all new cancer diagnoses. The lung cancer incidence is gradually increasing, especially among women and young people, but the fraction of cured patient remains low. In 80% of cases lung cancer, in early phase, is treatable only with surgery without chemotherapy or adjuvant radiotherapy and the survival perspective at five years exceeds 70%. Several scientific guidelines recommends chest CT (computed tomography) in lung cancer screening. Digital tomosynthesis (DTS) is a limited angle tomography that allows reconstruction of coronal images from a set of projection acquired over a small angle of X-ray tube movement. Several studies demonstrates that DTS is a reasonable alternative to the CT and allows a better evaluation of suspects nodules compared to conventional chest RX.

Lung cancer is the leading cause of cancer-related death around the world. In 2008 there were nearly 1.6 million new cases worldwide, accounting for the 12.7% of all new cancer diagnoses. Despite decreasing trends in smoking and resulting decrease in lung cancer mortality, the population at risk for lung cancer continues to be large. In the past years several programs have been developed to screen for lung cancer using low-dose chest computed radiography (CT). However, only recently different studies demonstrated a clear reduction in mortality. In particular, NLST low dose CT screening trial demonstrated a 6.7% reduction in the death rate compared to chest X-ray with a positive screening test rate for lung cancer detection of 24.2%, compared to 6.9% for conventional X-ray. Digital tomosynthesis (DTS) is a limited angle tomography that allows reconstruction of multiple image planes from a set of projection data acquired over a relatively small angle of X-ray tube movement. Although it does not have the spatial depth resolution of computed tomography, it provides high-resolution images in the sagittal planes at a lower dose and cost than CT. Several studies have shown that DTS offers advantages over conventional chest X-ray and comparable of those of CT. The Studio OSservazionale (SOS) was a clinical trial conducted within Santa Croce e Carle Hospital analysing smokers and former smokers aged 45-80 with no cancer diagnosis. All the subjects in whom a suspicious nodule was detected by DTS underwent diagnostic CT. The SOS study demonstrated that baseline DTS detected pulmonary abnormalities in 14.5% and lung cancer in 1.0% of the subjects, comparable to results that are obtained in CT screening programs. A second DTS, within the same study, executed one year later reported pulmonary abnormalities in 0.7% and lung cancer in 0.3% of the subjects.

Inclusion Criteria:

• current or former smoker status;
• for former smokers, the maximum time since quitting smoking must be below 10 years;
• smoking history of at least 20 pack-years;
• age 45-80 years;
• no previous history of cancer in the 10 years before the beginning of the study;
• be able to stand and hold the breath for 11 seconds during image acquisition;
• previous participation to SOS trial.

Exclusion Criteria:

• pregnancy