Characterisation of a MOSFET-based detector for dose measurement under megavoltage electron beam radiotherapy

Jong, Wei Loong and Ung, Ngie Min and Tiong, Aaron H.L. and Rosenfeld, Anatoly B. and Wong, Jeannie Hsiu Ding (2018) Characterisation of a MOSFET-based detector for dose measurement under megavoltage electron beam radiotherapy. Radiation Physics and Chemistry, 144. pp. 76-84. ISSN 0969-806X, DOI

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The aim of this study is to investigate the fundamental dosimetric characteristics of the MOSkin detector for megavoltage electron beam dosimetry. The reproducibility, linearity, energy dependence, dose rate dependence, depth dose measurement, output factor measurement, and surface dose measurement under megavoltage electron beam were tested. The MOSkin detector showed excellent reproducibility (>98%) and linearity (R2= 1.00) up to 2000 cGy for 4–20 MeV electron beams. The MOSkin detector also showed minimal dose rate dependence (within ±3%) and energy dependence (within ±2%) over the clinical range of electron beams, except for an energy dependence at 4 MeV electron beam. An energy dependence correction factor of 1.075 is needed when the MOSkin detector is used for 4 MeV electron beam. The output factors measured by the MOSkin detector were within ±2% compared to those measured with the EBT3 film and CC13 chamber. The measured depth doses using the MOSkin detector agreed with those measured using the CC13 chamber, except at the build-up region due to the dose volume averaging effect of the CC13 chamber. For surface dose measurements, MOSkin measurements were in agreement within ±3% to those measured using EBT3 film. Measurements using the MOSkin detector were also compared to electron dose calculation algorithms namely the GGPB and eMC algorithms. Both algorithms were in agreement with measurements to within ±2% and ±4% for output factor (except for the 4 × 4 cm2 field size) and surface dose, respectively. With the uncertainties taken into account, the MOSkin detector was found to be a suitable detector for dose measurement under megavoltage electron beam. This has been demonstrated in the in vivo skin dose measurement on patients during electron boost to the breast tumour bed.

Item Type: Article
Funders: University of Malaya Postgraduate Research Fund PPP (Grant number PG202-2015B)
Uncontrolled Keywords: MOSkin; Radiochromic film; EBT3; Quality assurance; Superficial dose
Subjects: R Medicine
Divisions: Faculty of Medicine
Depositing User: Ms. Juhaida Abd Rahim
Date Deposited: 31 Jul 2019 04:29
Last Modified: 31 Jul 2019 04:29

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