calculating {HEAD ~ a difference} between {TAIL ~ the known volume} of the cavity and the measured volume of discharged fluid into the cavity to determine the volume of the persons body 
calculating { HEAD ~ a difference } between { TAIL ~ the known volume } of the cavity and the measured volume of discharged fluid into the cavity to determine the volume of the persons body
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH