Small calcified foci in the lungs are mostly imaging changes left after the lungs have healed from chronic infectious diseases. Calcified foci are mostly seen in tuberculosis infections, such as patients who have had previous tuberculosis infections with symptoms such as cough, sputum, hot flashes, night sweats, and blood in the sputum. When given standardized anti-tuberculosis treatment for more than six months, polymorphic changes such as proliferation, nodules, calcification, and even cavity formation can appear in the lungs. Calcifications, in particular, indicate that the patient has had previous tuberculosis infection. Calcified foci are also seen in long-term smokers as well as those who work with dust, including masons, coal miners, cooks, hairdressers, and chemical workers. Long-term inhalation of allergic dust and odor irritation predispose to the formation of calcified foci in the lungs. Calcified foci are mostly benign changes with no clinical symptoms and do not require special treatment, only dynamic follow-up with chest CT. Patients who smoke are advised to quit smoking.