Caroline Lafond1, Sophie Chiavassa2, Cindy Bertaut3, Nicolas Boussion4, Nathalie Chapel5, Lucie Chapron6, Frédéric Coste7, Sylvain Crespin8, Gilles Dy9, Papa Abdoulaye Faye2, Cyril Leleu10, Jeanne Bouvier3, Ludovic Madec11, Jérôme Mesgouez12, Jérémy Palisson13, Anthony Vela14, Grégory Delpon2. 1. Centre Eugène Marquis, 35042 Rennes, France. Electronic address: c.lafond@rennes.unicancer.fr. 2. Institut de Cancérologie de l'Ouest Centre René Gauducheau, 44805 Saint-Herblain, Nantes, France. 3. Centre Eugène Marquis, 35042 Rennes, France. 4. CHRU, 29609 Brest, France. 5. Clinique Pasteur, 29200 Brest, France. 6. Clinique Armoricaine, 22000 Saint-Brieuc, France. 7. Pôle Mutualiste, 44600 Saint-Nazaire, France. 8. CHD Les Oudairies, 85925 La Roche sur Yon, France. 9. Clinique Saint-Vincent, 35760 Saint-Grégoire, France. 10. CHI, 29000 Quimper, France. 11. Centre de la Baie, 50300 Avranches, France. 12. Institut de Cancérologie de l'Ouest Centre Paul Papin, 49100 Angers, France. 13. Centre Mallet-Proux, 53000 Laval, France. 14. Centre François Baclesse, 14000 Caen, France.
Abstract
PURPOSE: Static beam intensity-modulated-radiation-therapy (IMRT) and/or Volumetric-Modulated-Arc-Therapy (VMAT) are now available in many regional radiotherapy departments. The aim of this multi-institutional audit was to design a new methodology based on radiochromic films to perform an independent quality control. METHODS: A set of data were sent to all participating centres for two clinical localizations: prostate and Head and Neck (H&N) cancers. The agreement between calculations and measurements was verified in the Octavius phantom (PTW) by point measurements using ionization chambers and by 2D measurements using EBT3 radiochromic films. Due to uncertainties in the whole procedure, criteria were set to 5% and 3% in local dose and 3mm in distance excluding doses lower than 10% of the maximum doses. No normalization point or area was used for the quantitative analysis. RESULTS: 13 radiotherapy centres participated in this audit involving 28 plans (12 IMRT, 16 VMAT). For point measurements, mean errors were -0.18±1.54% and 0.00±1.58% for prostate and H&N cases respectively. For 2D measurements with 5%/3mm criteria, gamma map analysis showed a pixel pass rate higher than 95% for prostate and H&N. Mean gamma index was lower than 0.4 for prostate and 0.5 for H&N. Both techniques yielded similar results. CONCLUSION: This study showed the feasibility of an independent quality control by peers for conventional IMRT and VMAT. Results from all participating centres were found to be in good agreement. This regional study demonstrated the feasibility of our new methodology based on radiochromic films without dose normalization on a specific point.
PURPOSE: Static beam intensity-modulated-radiation-therapy (IMRT) and/or Volumetric-Modulated-Arc-Therapy (VMAT) are now available in many regional radiotherapy departments. The aim of this multi-institutional audit was to design a new methodology based on radiochromic films to perform an independent quality control. METHODS: A set of data were sent to all participating centres for two clinical localizations: prostate and Head and Neck (H&N) cancers. The agreement between calculations and measurements was verified in the Octavius phantom (PTW) by point measurements using ionization chambers and by 2D measurements using EBT3 radiochromic films. Due to uncertainties in the whole procedure, criteria were set to 5% and 3% in local dose and 3mm in distance excluding doses lower than 10% of the maximum doses. No normalization point or area was used for the quantitative analysis. RESULTS: 13 radiotherapy centres participated in this audit involving 28 plans (12 IMRT, 16 VMAT). For point measurements, mean errors were -0.18±1.54% and 0.00±1.58% for prostate and H&N cases respectively. For 2D measurements with 5%/3mm criteria, gamma map analysis showed a pixel pass rate higher than 95% for prostate and H&N. Mean gamma index was lower than 0.4 for prostate and 0.5 for H&N. Both techniques yielded similar results. CONCLUSION: This study showed the feasibility of an independent quality control by peers for conventional IMRT and VMAT. Results from all participating centres were found to be in good agreement. This regional study demonstrated the feasibility of our new methodology based on radiochromic films without dose normalization on a specific point.
Authors: Enrica Seravalli; Antonetta C Houweling; Leo Van Battum; Thom A Raaben; Marc Kuik; Jacco A de Pooter; Marion P R Van Gellekom; Jochem Kaas; Wilfred de Vries; Erik A Loeff; Jeroen B Van de Kamer Journal: Phys Imaging Radiat Oncol Date: 2018-02-02