Ouch! This is why they have instrument and towel counts - this will lead to a generous settlement, I bet, because that x-ray is incredibly powerful plaintiff's evidence.
Actually, one of the cases that created the clear precedent that military members generally can't sue the government for injury or death that occurs while they are on active duty (aka the Feres doctrine) involved a guy who underwent abdominal surgery, then had constant pain and infections. When they opened him back up, months later, they found an 18x30" towel marked "Property of the U.S. Army"!