Is IMAT the ultimate evolution of conformal radiotherapy? Dosimetric comparison of helical tomotherapy and volumetric modulated arc therapy for oropharyngeal cancer in a planning study.
BACKGROUND
Intensity Modulated Arc Therapy (IMAT) can be planned and delivered via several techniques. Advanced Radiotherapy (ARTORL) is a prospective study that aims to evaluate the treatment costs and clinical aspects of implementing these IMAT techniques for head and neck cancers. In this context, we evaluated the potential dosimetric gain of Helical Tomotherapy (TomoTherapy, Accuray, HT) versus VMAT (Rapid'Arc(®), Varian Medical System, RA) for oropharyngeal cancer (OC).


METHODS
Thirty patients were selected from our database in whom bilateral neck irradiation and treatment to the primary were indicated. Each patient was planned twice using both HT and RA planning systems using a simultaneous integrated boost approach. For the planning target volumes (PTV) and organs at risk, ICRU 83 reporting guidelines were followed. RA and HT plans were compared using paired Student's t-test.


RESULTS
RA and HT produced plans with a good coverage of PTVs and acceptable sparing of OARs. Although some dosimetric differences were statistically significant, they remained small. However, the near maximal dose to the PRV of spinal cord and brain stem was lower with HT. Regarding normal tissue, HT increased the volume irradiated at doses between 4 and 20 Gy compared to RA.


CONCLUSIONS
In OC, HT and RA showed similar dosimetric results. They represent the maximum gains obtained with photon beams. The medicoeconomic evaluation of our study is ongoing and may reveal differences between these techniques in terms of MU number, fraction time, and clinical evaluation.
Department of Radiation Oncology, Besançon University Hospital, Besançon, France; University of Franche Comté, IRMA/LCPR-AC/CE UMR 6249 CNRS, Montbéliard, France. Electronic address: stephanie.servagi@gmail.com.
Stéphanie
S
Servagi Vernat
Paris Descartes University, Department of Radiation Oncology, Georges Pompidou European Hospital, Paris, France.
David
D
Ali
Clinical Methodology Center, Besançon University Hospital, Besançon, France.
Marc
M
Puyraveau
AQUILAB, Loos les Lille, France.
Romain
R
Viard
Department of Radiation Oncology, Centre René Gauducheau, Saint-Herblain, France.
Albert
A
Lisbona
Department of Radiation Oncology, Cancer Center Val D'Aurelle, Montpellier, France.
Pascal
P
Fenoglietto
Department of Radiation Oncology, Cancer Center Val D'Aurelle, Montpellier, France.
Ludovic
L
Bedos
University of Franche Comté, IRMA/LCPR-AC/CE UMR 6249 CNRS, Montbéliard, France.
Libor
L
Makovicka
Paris Descartes University, Department of Radiation Oncology, Georges Pompidou European Hospital, Paris, France.
Philippe
P
Giraud
D006801:Humans; D058958:Organs at Risk / Q000528:radiation effects; D009959:Oropharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011859:Radiography; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*
Dosimetric comparison; Double-arc intensity modulated arc therapy; Head and neck cancer; Helical Tomotherapy