By description of this modifier in the CPT 2008 Professional Edition, page 457 - "Bilateral Procedures - Unless otherwise identified in the listings, bilateral procedures that are performed at the [B]same operative session[B] should be identified by adding modifier 50 to the appropriate five digit code." Because it specifically states "same operative session" this indicates to this certified coder that it can only surgical codes codes. X-rays that are billed independently of surgical procedures, therefore, should not be billed with Mod 50. I can tell you that the insurance company I work for does not recognize Mod 50 on x-rays and only pays for 1 x-ray when providers bill Mod 50 on one line with a qty of 1.