Validation of secondary dose calculation system with manufacturer-provided reference beam data using heterogeneous phantoms

  • Yuji NakaguchiEmail author
  • Yuya Nakamura
  • Yohei Yotsuji


The Mobius3D (M3D) system (Mobius Medical Systems) is a second-check dosimetry system. We investigated the dose calculation accuracy of this system using heterogeneous phantoms with reference beam data provided by the manufacturer using simple and patient plans. We compared the dose distributions between M3D and the treatment planning system, as well as the measurements in solid water phantoms, heterogeneous phantoms, and patient plans for Varian and Elekta accelerators. The M3D results agreed well with the measurements in the solid water phantoms for the simple plans. However, the accuracy of M3D appeared to depend on the type of accelerator, as indicated by the slight differences in the dose measurements. Furthermore, the M3D dose measurements differed by 5–10% in the lung and bone regions. Regarding the patient plans, we confirmed that M3D is reasonably accurate as a second-check system, despite the slight accelerator type-dependent dose difference.


Quality assurance Volumetric modulated arc therapy Dose verification Second-check dosimetry system Reference beam data 



The authors would like to thank Kensuke Tani (Euro Meditech Co. Ltd, Tokyo, Japan) and Hiroyuki Yoshioka (Euro Meditech Co. Ltd, Tokyo, Japan) for their help and discussions during this work.

Compliance with ethical standards

Conflict of interest

All authors have no conflicts of interest to disclose.

Ethical approval

All procedures in studies involving human participants were performed in accordance with the ethical standards of Kumamoto University Hospital, and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Japanese Society of Radiological Technology and Japan Society of Medical Physics 2019

Authors and Affiliations

  1. 1.Department of Radiological TechnologyKumamoto University HospitalKumamotoJapan

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