{HEAD ~ An effective amount} of a photosensitive agent for {TAIL ~ PDT} is administered to a patient 
{ HEAD ~ An effective amount } of a photosensitive agent for { TAIL ~ PDT } is administered to a patient
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH