RT Journal Article SR Electronic T1 Detection and quantification of pulmonary emphysema by computed tomography: a window of opportunity. JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 1001 OP 1004 DO 10.1136/thx.47.12.1001 VO 47 IS 12 A1 Morgan, M D YR 1992 UL http://thorax.bmj.com/content/47/12/1001.abstract AB