Age is important: TB is more common in young people, who are often frail, and diabetes mellitus also predisposes to TB. Type of work is important: Patients exposed to dust and welding are likely to develop calcified nodules in the lungs. Smoking is important: smoking more than 1 pack per day increases the chance of lung cancer. Old films are important: A year-old physical examination film with nodules of the same size is usually benign; if the nodules increase in size, they are more likely to be lung cancer. Thin film examination is important: uneven density inside the nodule, burr around it and pulling of adjacent pleura are mostly lung cancer.