Had Been In A Minor Car Accident. X-ray Showed Small Mild Focal Opacity In The Chest. Meaning?
This is nonspecific xray finding usually used to describe lung hyperdense loacalized lesions. Majority of such findings dont indicate anything serious but further evaluation is necessary just to rule out malignant disease. This can be caused by various causes but also it can mean nothing as well(such as xray artefact). If he doesnt smoke and doesnt have any smyptoms such as cough and blood coughing, pain in deep breath and weight loss I dont think you should be worried.
But if you want to know, in worst case it can be lung carcinoma and if this is right then he is lucky that it was accidentaly discovered in early phase when it can be pretty easily treated. Other diseases which can be considered are TB patch (if you are exposed to TB risk), calcium deposition due to some systemic disease (if he has associated arhtritis, skin rash, liver or kidney disease) or some mediastinal mass or tumor. This can be the beginning of all these conditions,but also he would have some other signs and symptoms.
Most common and most benign causes are previous healed pulmonary infections which are commonly detected as small opacities.
Repeated X XXXXXXX would show is there any size progression of this lesion and if yes then CT scan should be done as soon as possible.
WIsh you good health. If you have any questions I ll be glad to help. Regards