X rays, for instance, are absorbed to differing degrees by different internal organs, and to {HEAD ~ the greatest degree} by {TAIL ~ bones} 
by
X rays , for instance , are absorbed to differing degrees by different internal organs , and to { HEAD ~ the greatest degree } by { TAIL ~ bones }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL