Oxygen masks are commonly visible on chest imaging, as they are generally not removed before the examination is performed.
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 .
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 an NG tube. In order to ensure that this does not happen, it can be useful to look for connectors at the periphery of the image and to review other recent images.