Open AccessDefining the dose‐volume criteria for laryngeal sparing in locally advanced oropharyngeal cancer utilizing split‐field IMRT, whole‐field IMRT and VMAT
Author(s) -
Wilke Christopher,
Takiar Vinita,
Wang He,
Moreno Amy C.,
Tung ShihMing Samuel,
QuinlanDavidson Sean R.,
Garden Adam S.,
Rosenthal David I.,
Fuller Clifton D.,
Gunn Gary B.,
Reddy Jay P.,
Morrison William H.,
Wang Congjun,
Zhao George,
Hutcheson Katherine A.,
Phan Jack
Publication year - 2021
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1002/acm2.13009
Subject(s) - larynx , medicine , radiation therapy , nuclear medicine , head and neck cancer , thyroid cartilage , radiology , surgery
Purpose To determine the optimal dose‐volume constraint for laryngeal sparing using three commonly employed intensity modulated radiation therapy (IMRT) approaches in patients with oropharyngeal cancer treated to the bilateral neck. Materials and methods Thirty patients with stage II‐IVA oropharynx cancers received definitive radiotherapy with split‐field IMRT (SF‐IMRT) to the bilateral neck between 2008 and 2013. Each case was re‐planned using whole‐field IMRT (WF‐IMRT) and volumetric modulated arc therapy (VMAT) and plan quality metrics and dose to laryngeal structures was evaluated. Two larynx volumes were defined and compared on the current study: the Radiation Therapy Oncology Group (RTOG) larynx as defined per the RTOG 1016 protocol and the MDACC larynx defined as the components of the larynx bounded by the superior and inferior extent of the thyroid cartilage. Results Target coverage, conformity, and heterogeneity indices were similar in all techniques. The RTOG larynx mean dose was lower with WF‐IMRT than SF‐IMRT (22.1 vs 25.8 Gy; P < 0.01). The MDACC larynx mean dose was 17.5 Gy ± 5.4 Gy with no differences between the 3 techniques. WF‐IMRT and VMAT plans were associated with lower mean doses to the supraglottic larynx (42.1 vs 41.2 vs 54.8 Gy; P < 0.01) and esophagus (18.1 vs 18.2 vs 36 Gy; P < 0.01). Conclusions Modern whole field techniques can provide effective laryngeal sparing in patients receiving radiotherapy to the bilateral neck for advanced oropharyngeal cancers. Summary We evaluated laryngeal dose in patients with locally advanced oropharyngeal cancer treated to the bilateral neck using split‐field IMRT (SF‐IMRT), whole‐field IMRT (WF‐IMRT) and volumetric arc therapy (VMAT). All three techniques provided good sparing of laryngeal structures and were able to achieve a mean larynx dose < 33 Gy. There were no significant differences in dose to target structures or non‐laryngeal organs at risk among techniques.