TY - JOUR
T1 - Optimizing laryngeal sparing with intensity modulated radiotherapy or volumetric modulated arc therapy for unilateral tonsil cancer
AU - Moreno, Amy C.
AU - Wilke, Christopher
AU - Wang, He
AU - Tung, Shi Ming Samuel
AU - Pollard, Courtney
AU - Garden, Adam S.
AU - Morrison, William H.
AU - Rosenthal, David I.
AU - Fuller, Clifton D.
AU - Gunn, Gary B.
AU - Reddy, Jay P.
AU - Shah, Shalin J.
AU - Frank, Steven J.
AU - Takiar, Vinita
AU - Phan, Jack
N1 - Publisher Copyright:
© 2019
PY - 2019/4
Y1 - 2019/4
N2 - Background and purpose: Minimizing radiation dose exposure to nearby organs is key to limiting clinical toxicities associated with radiotherapy. Several treatment modalities such as split- or whole-field intensity-modulated radiotherapy (SF-IMRT, WF-IMRT)and volumetric modulated arc therapy (VMAT)are being used to treat tonsillar cancer patients with unilateral neck radiotherapy. Herein, we provide a modern dosimetric comparison of all three techniques. Materials and methods: Forty patients with tonsillar cancer treated with definitive, ipsilateral neck SF-IMRT were evaluated. Each patient was re-planned with WF-IMRT and VMAT techniques, and doses to selected organs-at-risk (OARs)including the larynx, esophagus, and brainstem were compared. Results: No significant differences in target coverage existed between plans; however, the heterogeneity index improved using WF-IMRT and VMAT relative to SF-IMRT. Compared to SF-IMRT, WF-IMRT and VMAT plans had significantly lower mean doses to the supraglottic larynx (31 Gy, 18.5 Gy, 17 Gy; p < 0.01), the MDACC-defined larynx (13.4 Gy, 10.5 Gy, 9.8 Gy; p < 0.01), and RTOG-defined larynx (15.8 Gy, 12.1 Gy, 11.1 Gy; p < 0.01), respectively. Mean esophageal dose was lowest with SF-IMRT over WF-IMRT and VMAT (5.9 Gy, 12.2 Gy, 11.1 Gy; p < 0.01)but only in the absence of lower neck disease. On average, VMAT plans had shorter treatment times and required less monitor units than both SF-IMRT and WF-IMRT. Conclusion: In the setting of unilateral neck radiotherapy, WF-IMRT and VMAT plans can be optimized to significantly improve dose sparing of critical structures compared to SF-IMRT. VMAT offers additional advantages of shorter treatment times and fewer required monitor units.
AB - Background and purpose: Minimizing radiation dose exposure to nearby organs is key to limiting clinical toxicities associated with radiotherapy. Several treatment modalities such as split- or whole-field intensity-modulated radiotherapy (SF-IMRT, WF-IMRT)and volumetric modulated arc therapy (VMAT)are being used to treat tonsillar cancer patients with unilateral neck radiotherapy. Herein, we provide a modern dosimetric comparison of all three techniques. Materials and methods: Forty patients with tonsillar cancer treated with definitive, ipsilateral neck SF-IMRT were evaluated. Each patient was re-planned with WF-IMRT and VMAT techniques, and doses to selected organs-at-risk (OARs)including the larynx, esophagus, and brainstem were compared. Results: No significant differences in target coverage existed between plans; however, the heterogeneity index improved using WF-IMRT and VMAT relative to SF-IMRT. Compared to SF-IMRT, WF-IMRT and VMAT plans had significantly lower mean doses to the supraglottic larynx (31 Gy, 18.5 Gy, 17 Gy; p < 0.01), the MDACC-defined larynx (13.4 Gy, 10.5 Gy, 9.8 Gy; p < 0.01), and RTOG-defined larynx (15.8 Gy, 12.1 Gy, 11.1 Gy; p < 0.01), respectively. Mean esophageal dose was lowest with SF-IMRT over WF-IMRT and VMAT (5.9 Gy, 12.2 Gy, 11.1 Gy; p < 0.01)but only in the absence of lower neck disease. On average, VMAT plans had shorter treatment times and required less monitor units than both SF-IMRT and WF-IMRT. Conclusion: In the setting of unilateral neck radiotherapy, WF-IMRT and VMAT plans can be optimized to significantly improve dose sparing of critical structures compared to SF-IMRT. VMAT offers additional advantages of shorter treatment times and fewer required monitor units.
KW - Dosimetry
KW - IMRT
KW - Oropharynx
KW - Split-field
KW - Tonsillar cancer
KW - Unilateral neck radiotherapy
KW - VMAT
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UR - http://www.scopus.com/inward/citedby.url?scp=85070485432&partnerID=8YFLogxK
U2 - 10.1016/j.phro.2019.04.002
DO - 10.1016/j.phro.2019.04.002
M3 - Article
C2 - 33458265
AN - SCOPUS:85070485432
SN - 2405-6316
VL - 10
SP - 29
EP - 34
JO - Physics and Imaging in Radiation Oncology
JF - Physics and Imaging in Radiation Oncology
ER -