As Michele stated, they're saying you can use modifier (26/sometimes PC for some carriers) to show the professional component aka the "interpretation/reading only of the x-ray) if that's what the doctor did. The technical component would only be for equipment/supplies, tech and NOT the reading/interpretation and you'd use TC as the modifier, and if the provider provided the professional and technical aspects, then you'd bill the global CPT code w/o any modifiers. Some carriers will only pay the professional component to a specialist who isn't a Radiologist or is accredited, or they restrict what types of radiology services a specialist outside of a Radiologist can do. Most carriers will usually restrict the more advanced radiology stuff like, CT, MRI, nuclear stuff, to Radiologist or those accredited. Meaning they'll pay for both components if, in fact, the doctor provided both as long as it's not the aforementioned. You can see UHC's policy regarding this here -->
https://www.unitedhealthcareonline.com/b2c/CmaAction.do?channelId=dda436d4b6e32110VgnVCM100000c520720a____ see the reference material.
I have a question about the PA/MD situation---> If the PA and the doctor were in the office and it's an established patient then why aren't you guys following CMS/Medicare's rules about incident-to for NPP's (non-physician provider), where you bill the services under the supervising MD/DO? Just curious. Most carriers (including United) tend to follow Medicare's guidelines w/incident-to, but confirm with them to be sure. Now if the supervising MD wasn't in the office (for groups it's any doctor in the group in the practice at the time) or the patient had a new problem and the PA discovered this and ordered the x-ray because of this, then the incident-to wouldn't be used, you'd have to bill under the PA. If incident-to applies then it's just a suggestion that you look into this more, again check all the guidelines so you understand how this works or have your coder look into it, as they should be aware of this too.
You can see an overview of CMS/Medicare's incident-to here --->
http://www.cms.gov/Outreach-and-Education/Medicare-Learning-Network-MLN/MLNMattersArticles/downloads/se0441.pdf Here is an article on AAPC --->
http://news.aapc.com/index.php/2013/03/3-tips-guide-successful-incident-to-billing/. Lastly you can check Medicare's Benefit Policy Manual -->
http://www.cms.gov/Regulations-and-Guidance/Guidance/Manuals/downloads/bp102c15.pdf.