{HEAD ~ The grid} of this invention is of {TAIL ~ an air core type}, eliminating the x ray transparent material of the prior known grids 
is of
{ HEAD ~ The grid } of this invention is of { TAIL ~ an air core type } , eliminating the x ray transparent material of the prior known grids
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH