Characterization of a gated fiber-optic-coupled detector for application in clinical electron beam dosimetry

Department of Radiation Medicine, Oregon Health and Science University, Portland, Oregon 97239, USA.
Medical Physics (Impact Factor: 2.64). 02/2011; 38(2):961-7. DOI: 10.1118/1.3539737
Source: PubMed

ABSTRACT Assessment of the fundamental dosimetric characteristics of a novel gated fiber-optic-coupled dosimetry system for clinical electron beam irradiation.
The response of fiber-optic-coupled dosimetry system to clinical electron beam, with nominal energy range of 6-20 MeV, was evaluated for reproducibility, linearity, and output dependence on dose rate, dose per pulse, energy, and field size. The validity of the detector system's response was assessed in correspondence with a reference ionization chamber.
The fiber-optic-coupled dosimetry system showed little dependence to dose rate variations (coefficient of variation +/- 0.37%) and dose per pulse changes (with 0.54% of reference chamber measurements). The reproducibility of the system was +/- 0.55% for dose fractions of approximately 100 cGy. Energy dependence was within +/- 1.67% relative to the reference ionization chamber for the 6-20 MeV nominal electron beam energy range. The system exhibited excellent linear response (R2 = 1.000) compared to reference ionization chamber in the dose range of 1-1000 cGy. The output factors were within +/- 0.54% of the corresponding reference ionization chamber measurements.
The dosimetric properties of the gated fiber-optic-coupled dosimetry system compare favorably to the corresponding reference ionization chamber measurements and show considerable potential for applications in clinical electron beam radiotherapy.

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