Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph obtained . There is bibasilar opacity , likely atelectasis , though a component of aspiration not excluded . No large effusion or pneumothorax . Cardiomediastinal silhouette appears grossly unremarkable aside from an unfolded partially calcified thoracic aorta . No definite bony injuries are seen .
    OUTPUT:
    
Bibasilar atelectasis , possible mild aspiration . Otherwise , no acute findings .