title: Assessing the feasibility of volumetric-modulated arc therapy using simultaneous integrated boost (SIB-VMAT): An analysis for complex head-neck, high-risk prostate and rectal cancer cases.
abstract: Intensity-modulated radiotherapy (IMRT) allowed the simultaneous delivery of different doses to different target volumes within a single fraction, an approach called simultaneous integrated boost (SIB). As consequence, the fraction dose to the boost volume can be increased while keeping low doses to the elective volumes, and the number of fractions and overall treatment time will be reduced, translating into better radiobiological effectiveness. In recent years, volumetric-modulated arc therapy (VMAT) has been shown to provide similar plan quality with respect to fixed-field IMRT but with large reduction in treatment time and monitor units (MUs) number. However, the feasibility of VMAT when used with SIB strategy has few investigations to date. We explored the potential of VMAT in a SIB strategy for complex cancer sites. A total of 15 patients were selected, including 5 head-and-neck, 5 high-risk prostate, and 5 rectal cancer cases. Both a double-arc VMAT and a 7-field IMRT plan were generated for each case using Oncentra MasterPlan treatment planning system for an Elekta Precise linac. Dosimetric indexes for targets and organs at risk (OARs) were compared based on dose-volume histograms. Conformity index, homogeneity index, and dose-contrast index were used for target analyses. The equivalent uniform doses and the normal tissue complication probabilities were calculated for main OARs. MUs number and treatment time were analyzed to score treatment efficiency. Pretreatment dosimetry was performed using 2-dimensional (2D)-array dosimeter. SIB-VMAT plans showed a high level of fluence modulation needed for SIB treatments, high conformal dose distribution, similar target coverage, and a tendency to improve OARs sparing compared with the benchmark SIB-IMRT plans. The median treatment times reduced from 13 to 20 minutes to approximately 5 minutes for all cases with SIB-VMAT, with a MUs reduction up to 22.5%. The 2D-array ion-chambers' measurements reported an agreement of more than 95% for a criterion of 3% to 3mm. SIB-VMAT was able to combine the advantages of conventional SIB-IMRT with its highly conformal dose distribution and OARs sparing and the advantages of 3D-conformal radiotherapy with its fast delivery.
authors.affiliation: Medical Physics Unit, Fondazione di ricerca e cura "Giovanni Paolo II," Università Cattolica del Sacro Cuore, Campobasso, Italy. Electronic address: savinocilla@gmail.com.
authors.forename: Savino
authors.initials: S
authors.lastname: Cilla
authors.affiliation: Radiation Oncology Unit, Fondazione di ricerca e cura "Giovanni Paolo II," Università Cattolica del Sacro Cuore, Campobasso, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Deodato
authors.affiliation: Radiation Oncology Unit, Fondazione di ricerca e cura "Giovanni Paolo II," Università Cattolica del Sacro Cuore, Campobasso, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Digesù
authors.affiliation: Radiation Oncology Unit, Fondazione di ricerca e cura "Giovanni Paolo II," Università Cattolica del Sacro Cuore, Campobasso, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Macchia
authors.affiliation: Radiation Oncology Unit, Fondazione di ricerca e cura "Giovanni Paolo II," Università Cattolica del Sacro Cuore, Campobasso, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Picardi
authors.affiliation: Radiation Oncology Unit, Fondazione di ricerca e cura "Giovanni Paolo II," Università Cattolica del Sacro Cuore, Campobasso, Italy.
authors.forename: Marica
authors.initials: M
authors.lastname: Ferro
authors.affiliation: Radiology Unit, Fondazione di ricerca e cura "Giovanni Paolo II," Università Cattolica del Sacro Cuore, Campobasso, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Sallustio
authors.affiliation: Physics Institute, Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: De Spirito
authors.affiliation: Physics Institute, Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Piermattei
authors.affiliation: Radiation Oncology Unit, Fondazione di ricerca e cura "Giovanni Paolo II," Università Cattolica del Sacro Cuore, Campobasso, Italy.
authors.forename: Alessio G
authors.initials: AG
authors.lastname: Morganti
mesh_terms: D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005240:Feasibility Studies; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012004:Rectal Neoplasms / Q000532:radiotherapy*; D012307:Risk Factors; D018511:Systems Integration; D016896:Treatment Outcome
keywords: Head-neck cancer; High-risk prostate cancer; Rectal cancer; SIB; VMAT