Frequency of chest x-ray in 4,731 subjects in seven metropolitan cities.
D000293:Adolescent; D000328:Adult; D005260:Female; D006266:Health Education; D006801:Humans; D008297:Male; D008400:Mass Chest X-Ray; D008875:Middle Aged; D011634:Public Health; D012424:Rural Population; D013223:Statistics as Topic; D014481:United States