Although I don't think there is an 'Oral Cancer' specific NCCN Protocols for PET/CT scans (as there are for many cancers), there is a general NCCN Protocol released in 2007 that covers PET/CT use, testing, training and evaluation certification requirements.

In 2009 the NCCN released a PET/CT protocol supplement stated that based on reported survey data 80% of PET scanners in the US CCC's have been replaced with PET/CT scanners. It also found that the nearly all of these new scanners generate a diagnostic quality CT scan.

In the 2009 supplemental the NCCN mentions several studies from major CCC's that have found as a diagnostic tool the fused PET/CT scan was roughly 10% better than a PET scan plus a separate CT scan and roughly 20% better than a CT scan study alone, or a MRI (with contrast study) alone and that a significant percentage of physicians change their treatment plan after a PET/CT.

The current NCCN Head & Neck Cancer Guidelines (ver 2.2011) have increased recommendations for use of PET/CT scans particularly when staging is a III or IV, and state that post chemo/RT a PET/CT is considered 90% reliable in establishing a clinical finding (of course that is when the established protocol is properly followed).

Since 2007, many major CCC's have move from 18F-FDG tracer to 18F-FLT for post chemo/rt PET/CT scans. The 'FLT' tracer has a demonstrated ability to better differentiate cancer uptake from inflammation. Numerous other tracers are undergoing testing and some trials.

The quality of PET/CT scanners have significantly improved. In 2009 a NCCN survey found ~1800 in use in the US and stated that 100% of PET scanner manufactured and sold since 2007 are PET/CT scanners.

Like most everything, scans have limitations. PET/CT scanner, like many other things, seem to be getting better.