Investigating the effect of a magnetic field on dose distributions at phantom-air interfaces using PRESAGE® 3D dosimeter and Monte Carlo simulations
作者： Filipa Costa , Simon J Doran , Ian M Hanson , Simeon Nill , Ilias Billas
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摘要: Dosimetric quality assurance (QA) of the new Elekta Unity (MR-linac) will differ from QA performed a conventional linac due to constant magnetic field, which creates an electron return effect (ERE). In this work we aim validate PRESAGE® dosimetry in transverse and assess its use research version Monaco TPS MR-linac. Cylindrical samples 3D dosimeter separated by air gap were irradiated with cobalt-60 unit, while placed between poles electromagnet at 0.5 T 1.5 T. This set-up was simulated EGSnrc/Cavity Monte Carlo (MC) code relative dose distributions compared measurements using 1D 2D gamma criteria 3% mm. The irradiation conditions adapted for MR-linac simulations. Measured profiles showed good agreement passing rate 99.9% 99.8% Measurements on also well simulations, 98.4% Results demonstrated that can accurately measure detect ERE, encouraging as tool clinically relevant tissue-air boundaries.
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