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.

Abstract

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).

MATERIAL AND 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.

CONCLUSION:

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.

• Authors: Stéphanie Servagi Vernat, David Ali, Marc Puyraveau, Romain Viard, Albert Lisbona, Pascal Fenoglietto, Ludovic Bedos, Libor Makovicka, Philippe Giraud
• Journal: Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) (Phys Med) Vol. 30 Issue 3 Pg. 280-5 (May 2014) ISSN: 1724-191X [Electronic] Italy
• PMID: 23948367 (Publication Type: Comparative Study, Journal Article)
• Copyright: Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Topics

• Humans
• Organs at Risk (radiation effects)
• Oropharyngeal Neoplasms (diagnostic imaging, radiotherapy)
• Radiography
• Radiometry
• Radiotherapy Planning, Computer-Assisted (methods)
• Radiotherapy, Intensity-Modulated (adverse effects, methods)