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