The process or result of separating a sample into sub-samples according to specified criteria, such as age or occupational group.
internationally recognized recommendations for the follow-up for incidentally discovered nodules on a CT scan of the chest that may be early carcinomas. This is designed for nodules smaller than 8 mm and not amenable to biopsy. The patients are divided into low- and high-risk groups. Risk stratification will depend on smoking history and other factors, such as asbestos exposure. Nodules are divided into four groups: less than 4 mm, 4–6 mm, 6–8 mm, and 8 mm or larger. Low-risk patients with nodules smaller than 4 mm receive no follow-up; for larger nodules or in high-risk patients scans are performed at 3, 6, 9, 12, and 24 months according to size and risk levels. [F. Fleischner (1893–1969), Austrian-born US radiologist]... fleischner criteria
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