After reading, i believe,
your doctor is trying to seen if there are any features of active infection in your lungs.
Since your chief complaints are not mentioned in query for which this radiograph was done its difficult to say much with certainty
however let me explain
there features mentioned in chest radio graph indicating indirect features of infection in lung's upper part, which needs to be further clarified by taking additional view (apico lardotic view) weather there features are indicative of active infection or just residual scars
of some old infection in lung.
crowding of the pulmonary vascular markings
in the left suprahilar region also helps to find out the same.