Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-erect AP chest demonstrates low lung volumes , in incomplete penetration . There is a new right basilar opacity , which might represent atelectasis , though early infection is not excluded . Cardiac silhouette is stable , the mediastinal contours are stable notable for atherosclerotic calcification of the arch .
    OUTPUT:
    
Right basilar opacity , new compared with prior which might be the result of atelectasis , though infection is not excluded in the appropriate clinical setting .