title: A comparative study of standard intensity-modulated radiotherapy and RapidArc planning techniques for ipsilateral and bilateral head and neck irradiation.
abstract: The purpose of this study was to investigate class solutions using RapidArc volumetric-modulated arc therapy (VMAT) planning for ipsilateral and bilateral head and neck (H&N) irradiation, and to compare dosimetric results with intensity-modulated radiotherapy (IMRT) plans. A total of 14 patients who received ipsilateral and 10 patients who received bilateral head and neck irradiation were retrospectively replanned with several volumetric-modulated arc therapy techniques. For ipsilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the contralateral parotid, two 260° or 270° arcs, and two 210° arcs. For bilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the shoulders, and 3 arcs. All patients had a sliding-window-delivery intensity-modulated radiotherapy plan that was used as the benchmark for dosimetric comparison. For ipsilateral neck irradiation, a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid was dosimetrically comparable to intensity-modulated radiotherapy, with improved conformity (conformity index = 1.22 vs 1.36, p < 0.04) and lower contralateral parotid mean dose (5.6 vs 6.8Gy, p < 0.03). For bilateral neck irradiation, 3-arc volumetric-modulated arc therapy techniques were dosimetrically comparable to intensity-modulated radiotherapy while also avoiding irradiation through the shoulders. All volumetric-modulated arc therapy techniques required fewer monitor units than sliding-window intensity-modulated radiotherapy to deliver treatment, with an average reduction of 35% for ipsilateral plans and 67% for bilateral plans. Thus, for ipsilateral head and neck irradiation a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid is recommended. For bilateral neck irradiation, 2- or 3-arc techniques are dosimetrically comparable to intensity-modulated radiotherapy, but more work is needed to determine the optimal approaches by disease site.
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women׳s Hospital, Boston, MA; Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA. Electronic address: jpursley@mgh.harvard.edu.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Pursley
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women׳s Hospital, Boston, MA.
authors.forename: Antonio L
authors.initials: AL
authors.lastname: Damato
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women׳s Hospital, Boston, MA.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Czerminska
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women׳s Hospital, Boston, MA.
authors.forename: Danielle N
authors.initials: DN
authors.lastname: Margalit
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women׳s Hospital, Boston, MA; Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX.
authors.forename: David J
authors.initials: DJ
authors.lastname: Sher
authors.affiliation: Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women׳s Hospital, Boston, MA.
authors.forename: Roy B
authors.initials: RB
authors.lastname: Tishler
mesh_terms: D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D059351:Organ Sparing Treatments; D058958:Organs at Risk; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*
keywords: Dosimetry; Head and neck cancer; IMRT; RapidArc; VMAT