How Can a Radiolucent Foreign Body Be Imaged?
Most bronchial foreign bodies (including foods and plastics) don’t contain metal or glass, and therefore can’t be seen on normal Xrays.
Special Xrays (taken during Inspiration and Expiration) may show air trapping in one lung, beyond a “radiolucent” foreign body.
In this case, the Xray taken during Inspiration looks normal, even though a peanut is partially obstructing the patient’s right main bronchus.
During Expiration, the right lung can’t deflate properly. This causes the heart to shift far to the patient’s left (towards the right of your computer screen).