Volumetric-modulated arc therapy lung stereotactic body radiation therapy dosimetric quality assurance: A comparison between radiochromic film and chamber array

• Main Authors: Juan Fernando Mata Colodro, Alfredo Serna Berná, Vicente Puchades Puchades, David Ramos Amores, Miguel Alcaraz Baños
• Format: Article
• Language: English
• Published: Wolters Kluwer Medknow Publications 2017-01-01
• Series: Journal of Medical Physics
• Subjects: Ion chamber array; lung stereotactic body radiation therapy; radiochromic film; volumetric-modulated arc therapy
• Online Access: http://www.jmp.org.in/article.asp?issn=0971-6203;year=2017;volume=42;issue=3;spage=133;epage=139;aulast=Mata

Introduction: The aim of this work is to verify the use of radiochromic film in the quality assurance (QA) of volumetric-modulated arc therapy (VMAT) lung stereotactic body radiation therapy (SBRT) plans and compare the results with those obtained using an ion chamber array. Materials and Methods: QA was performed for 14 plans using a two-dimensional-array seven29 and EBT3 film. Dose values per session ranged between 7.5 Gy and 18 Gy. The multichannel method was used to obtain a dose map for film. Results: The results obtained were compared with treatment planning system calculated profiles through gamma analysis. Passing criteria were 3%/3 mm, 2%/2 mm and 3%/1.5 mm with maximum and local dose (LD) normalization. Mean gamma passing rate (GPR) (percentage of points presenting a gamma function value of <1) was obtained and compared. Calibration curves were obtained for each color channel within the dose range 0–16 Gy. Mean GPR values for film were> 98.9% for all criteria when normalizing per maximum dose. When using LD, normalization was> 92.7%. GPR values for the array were lower for all criteria; this difference being statistically significant when normalizing at LD, reaching 12% for the 3%/1.5 mm criterion. Conclusion: Both detectors provide satisfactory results for the QA of plans for VMAT lung SBRT. The film provided greater mean GPR values, afforded greater spatial resolution and was more efficient overall.