Impact of Multi-Institutional Prospective Peer Review on Target and Organ-at-Risk Delineation in Radiation Therapy

Abstract

Purpose: Peer review is an essential component of quality assurance programs in radiation oncology. The purpose of this work was to assess whether peer reviewers recommend expansion or reduction of planning target volumes (PTVs) and organs at risk (OARs) in prospective multidisciplinary daily contour rounds.

Methods and materials: The peer group evaluated the appropriateness of PTVs and OARs for each case according to evidence-based departmental directives. We reviewed 7645 cases that presented between September 2013 and March 2017. We isolated recommendations for PTV/OAR modification and classified each as expansion, reduction, both, or indeterminate. Recommendations were analyzed by technique, site, and physician experience.

Results: Eight junior and 7 senior radiation oncologists were included. PTV or OAR modifications were recommended for 750 of 7645 prescriptions (9.7%). The peer group recommended PTV modifications for 534 prescriptions (7.0%): There were 309 expansions (57.9%), 115 reductions (21.5%), 15 both (2.8%), and 95 indeterminate (17.8%). Reasons for PTV expansions included increased nodal coverage and inadequate margins as a result of motion. The peer group recommended OAR modifications for 216 prescriptions (2.8%): There were 102 expansions (47.2%), 23 reductions (10.6%), 2 both (0.9%), and 89 indeterminate (41.2%). Reasons for OAR expansions included missing critical structures and inadequate extent as per departmental standardization. Head and neck represented the largest percentage of PTV recommendations (28.8%). Intensity modulated radiation therapy plans received the most PTV and OAR recommendations (66.8% and 74.5%, respectively). The recommendation rate for senior and junior faculty was 43% and 28%, respectively.

Conclusions: Peer review resulted in recommendations for PTV or OAR change for approximately 10% of cases. Expansions of PTV were recommended >2.5 times more often than reductions and >3 times more often than OAR expansions. This general trend was identified for treatment technique, site, and physician experience. Prospective peer review could yield systematically larger volumes, which could affect multicenter clinical trials.