Oesophageal coins invisible on chest radiography: a case report.

Japanese 1-yen coins are made of 100% aluminium, which is less radiopaque than the metals that make up coins (nickel, bronze, and lead), and so, they were not visible via chest radiography in our case. Detecting very small or thin radiolucent foreign bodies is not possible using a chest radiograph or contrast oesophagram, but is possible via CT. CT is both increasingly convenient and non-invasive, unlike endoscopy or bronchoscopy, and so, the use of CT scans should be considered in cases of possible radiolucent foreign body ingestion.