Validation of the Mobius system for patient-specific quality assurance using introduced intentional errors

  • Ivy Win Long AuEmail author
  • Laura Ciurlionis
  • Neil Campbell
  • Daniel Goodwin
Scientific Note


Mobius3D and MobiusFX are model-based verification tools for treatment plan dose calculation and treatment delivery. The software facilitates patient-specific quality assurance by extracting data from linear accelerator treatment log files and performing a 3D dose calculation on the original patient CT dataset using an independent collapsed cone algorithm. In this study, we evaluate the ability of the Mobius system to detect linear accelerator-related errors compared with existing measurement-based systems, namely the ArcCHECK® and 3DVH® systems. Three original treatment plans and 47 plans with introduced delivery errors, for a total of 50 plan deliveries, were investigated. The results from this study demonstrated comparable gamma passing rates and error detectability between the Mobius and ArcCHECK® systems while the 3DVH system generally exhibited a lower sensitivity. This work also demonstrated the ability of the Mobius system to detect delivery errors of down to 2° collimator rotation, 1 mm MLC bank offset and 10 mm collimator jaw offset.


Patient specific QA Treatment verification VMAT Gamma analysis Introduced errors Mobius ArcCHECK 3DVH 


Compliance with ethical standards

Conflicts of interest

The authors declare that they have no conflicts of interest.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.


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Copyright information

© Australasian College of Physical Scientists and Engineers in Medicine 2016

Authors and Affiliations

  • Ivy Win Long Au
    • 1
    Email author
  • Laura Ciurlionis
    • 1
  • Neil Campbell
    • 1
  • Daniel Goodwin
    • 1
  1. 1.Auckland City HospitalAucklandNew Zealand

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