Background and purpose

While standard guidelines assist in target delineation for head and neck radiation therapy planning, the complex anatomy, varying patterns of spread, unusual or advanced presentations, and high risk of treatment-related toxicities produce continuous interpretive challenges. In 2007, we instituted weekly treatment planning quality assurance rounds as a joint enterprise of head and neck radiation oncology and neuroradiology. Here we describe its impact on head and neck radiation therapy target delineation.

Materials and methods

For 7 months, treatment planning quality assurance included 80 cases of definitive (48%) or postoperative (52%) head and neck radiation therapy. The planning CT and associated target volumes were reviewed in comparison with diagnostic imaging studies. Alterations were catalogued.

Results

Of the 80 cases, 44 (55%) were altered, and of these, 61% had clinically significant changes resulting in exclusion or inclusion of a distinct area or structure. Reasons for alteration included the following: gross or extant tumor, 26/44 (59%); elective or postoperative coverage, 25/44 (57%); lymph nodes, 13/44 (30%); bone, 7/44 (16%); skull base, 7/44 (16%); normal organs, 5/44 (11%); perineural, 3/44 (7%); distant metastasis, 2/44 (5%); and eye, 1/44 (2%). Gross tumor changes ranged from 0.5% to 133.64%, with a median change in volume of 5.95 mm³ (7.86%). Volumes were more likely to be increased (73%) than decreased (27%).

Conclusions

A collaborative approach to head and neck treatment planning quality assurance has an impact. Cases likely to have challenging patterns of infiltrative, intracranial, nodal, orbital, or perineural spread warrant intensive imaging-based review in collaboration with a diagnostic neuroradiologist.