title: Analyzing the performance of ArcCHECK diode array detector for VMAT plan.
abstract: OBJECTIVE
  The aim of this study is to evaluate performance of ArcCHECK diode array detector for the volumetric modulated arc therapy (VMAT) patient specific quality assurance (QA). VMAT patient specific QA results were correlated with ion chamber measurement. Dose response of the ArcCHECK detector was studied.
  
  
  BACKGROUND
  VMAT delivery technique improves the dose distribution. It is complex in nature and requires proper QA before its clinical implementation. ArcCHECK is a novel three dimensional dosimetry system.
  
  
  METHODS
  Twelve retrospective VMAT plans were calculated on ArcCHECK phantom. Point dose and dose map were measured simultaneously with ion chamber (IC-15) and ArcCHECK diode array detector, respectively. These measurements were compared with their respective TPS calculated values.
  
  
  RESULTS
  The ion chamber measurements are in good agreement with TPS calculated doses. Mean difference between them is 0.50% with standard deviation of 0.51%. Concordance correlation coefficient (CCC) obtained for ion chamber measurements is 0.9996. These results demonstrate a strong correlation between the absolute dose predicted by our TPS and the measured dose. The CCC between ArcCHECK doses and TPS predictions on the CAX was found to be 0.9978. In gamma analysis of dose map, the mean passing rate was 98.53% for 3% dose difference and 3 mm distance to agreement.
  
  
  CONCLUSIONS
  The VMAT patient specific QA with an ion chamber and ArcCHECK phantom are consistent with the TPS calculated dose. Statistically good agreement was observed between ArcCHECK measured and TPS calculated. Hence, it can be used for routine VMAT QA.
authors.affiliation: Division of Radiation Oncology, Medanta Cancer Institute, Medanta The Medicity, Gurgaon, India.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Thiyagarajan
authors.affiliation: School of Advanced Sciences, VIT University, Vellore, India.
authors.forename: Arunai
authors.initials: A
authors.lastname: Nambiraj
authors.affiliation: Medical Physics Division, Dept of Radiation Oncology, Rajiv Gandhi Cancer Institute and Research Centre, Delhi, India.
authors.forename: Sujit Nath
authors.initials: SN
authors.lastname: Sinha
authors.affiliation: Medical Physics Division, Dept of Radiation Oncology, Rajiv Gandhi Cancer Institute and Research Centre, Delhi, India.
authors.forename: Girigesh
authors.initials: G
authors.lastname: Yadav
authors.affiliation: Medical Physics Division, Dept of Radiation Oncology, Rajiv Gandhi Cancer Institute and Research Centre, Delhi, India.
authors.forename: Ashok
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Division of Radiation Oncology, Medanta Cancer Institute, Medanta The Medicity, Gurgaon, India.
authors.forename: Vikraman
authors.initials: V
authors.lastname: Subramani
authors.affiliation: Medical Physics Division, Dept of Radiation Oncology, Rajiv Gandhi Cancer Institute and Research Centre, Delhi, India.
authors.lastname: Kothandaraman
keywords: ArcCHECK; Diode array; Gamma; Quality assurance; VMAT