Mass x-ray surveys in North America.
D035843:Biomedical Research; D003625:Data Collection; D006331:Heart Diseases / Q000517:prevention & control*; D006801:Humans; D008175:Lung Neoplasms; D009656:North America; D014376:Tuberculosis; D014397:Tuberculosis, Pulmonary / Q000517:prevention & control*; D014965:X-Rays
HEART DISEASE/prevention and control; LUNGS/neoplasms; TUBERCULOSIS, PULMONARY/prevention and control