Original paper| Volume 70, P153-160, February 2020

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Impact of transverse magnetic fields on dose response of a nanoDot OSLD in megavoltage photon beams

Published:February 04, 2020DOI:


      • Impact of magnetic fields on the response of a nanoDot OSLD was investigated.
      • Response RQ,B varied depending on the magnetic field strength.
      • Variation of RQ,B reduced as the photon beam energy increased.
      • Top and bottom air- gaps affected the dose deposition due to the electron return effect (ERE).



      We investigated the impact of transverse magnetic fields on the dose response of a nanoDot optically stimulated luminescence dosimetry (OSLD) in megavoltage photon beams.


      The nanoDot OSLD response was calculated via Monte Carlo (MC) simulations. The responses RQ and RQ,B without and with the transverse magnetic fields of 0.35–3 T were analyzed as a function of depth at a 10 cm × 10 cm field for 4–18 MV photons in a solid water phantom. All responses were determined based on comparisons with the response under the reference conditions (depth of 10 cm and a 10 cm × 10 cm field) for 6 MV without the magnetic field. In addition, the influence of air-gaps on the nanoDot response in the magnetic field was estimated according to Burlin’s general cavity theory.


      The RQ as a function of depth for 4–18 MV ranged from 1.013 to 0.993, excepting the buildup region. The RQ,B increased from 2.8% to 1.5% at 1.5 T and decreased from 3.0% to 1.1% at 3 T in comparison with RQ as the photon energy increased. The depth dependence of RQ,B was less than 1%, excepting the buildup region. The top air-gap and the bottom air- gap were responsible for the response reduction and the response increase, respectively.


      The response RQ,B varied depending on the magnetic field intensity, and the variation of RQ,B reduced as the photon beam energy increased. The air-gaps affected the dose deposition in the magnetic fields.


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