Oxygen masks are commonly visible on chest imaging, as they are generally not removed before the examination is performed.
Radiographic features
Plain radiograph
Oxygen masks are of soft-tissue density and may mimic lung lesions. A nebuliser mask with liquid in its cup causing an air-fluid level can look like a lung abscess 1.
Oxygen tubing that projects over the chest on a frontal projection, especially in a midline craniocaudal orientation, may be difficult to see and confused with a nasogastric tube. To prevent this, it can be useful to look for connectors at the periphery of the image and review other recent images too.