Op den Orth J O, Ploem S
Radiology. 1975 Dec;117(3 Pt 1):523-5. doi: 10.1148/117.3.523.
Supine vertical beam films in double contrast studies of the stomach often show "barium spots" projecting on anterior wall polyps and folds. The supposition that these spots are caused by droplets of barium hanging from such protuberances is proved radiographically using horizontal beam techniques.