The lead provides for efficient attenuation of x rays, and the high percentage of open area provides for {HEAD ~ unrestricted passage} of {TAIL ~ the desired imaging x rays} 
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The lead provides for efficient attenuation of x rays , and the high percentage of open area provides for { HEAD ~ unrestricted passage } of { TAIL ~ the desired imaging x rays }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL