There are {HEAD ~ a number} of methods for producing {TAIL ~ images} of internal structures of a body 
There are { HEAD ~ a number } of methods for producing { TAIL ~ images } of internal structures of a body
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH