Impact of Neuroradiology-Based Peer Review on Head and Neck Radiotherapy Target Delineation

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.

Retrospective and prospective studies demonstrate increased efficacy from multidisciplinary physician interaction,^1,2 and team-based approaches to patient care are routine within radiation oncology. However, the process of radiation therapy target delineation remains an essentially solitary activity, and the impact of collaborative peer review is a contested issue. One survey suggested that major alterations from this type of process were rare, occurring in <6% of head and neck (HN) plans, though the extent of alterations was noted to be dependent on the reviewing peer''s subsite experience level.³The weakness of these studies as applied to HN cancer stems from a tendency to underestimate the specialized nature of anatomically defined HN radiation therapy and its unique interdependence with neuroradiology. Head and neck malignancies comprise a heterogeneous group of neoplasms characterized by complex local and regional anatomy, varying patterns of spread, and frequent occurrence of unusual and/or advanced presentations. Acquiring proficiency in the interpretation of HN imaging is difficult due to the subtlety of the characteristics that may suggest benign or malignant disease and distinguishing them from normal or inflamed tissue. Because management frequently consists of staged, multimodal combinations of surgery, systemic therapy, and/or radiation therapy, the interpretation of sequential image sets is exceptionally challenging, particularly the discrimination of posttreatment changes from residual disease.⁴ Previous studies have found that after re-interpretation by a specialist head and neck neuroradiologist, changes in staging or management occur in 38%–56% of cases.^5,6Beginning in 2007, diagnostic neuroradiology participation was included as part of weekly HN treatment planning quality assurance (TPQA) rounds at our institution. The format includes diagnostic imaging review for new and follow-up patients, as well as the highly prioritized review of proposed radiation therapy target volumes and normal organ delineations, which are peer-reviewed by HN radiation oncology and neuroradiology physicians. As of June 2010, electronic documentation was prepared pre- and post-TPQA. This study characterizes the impact of diagnostic neuroradiology involvement on the radiation therapy planning process.