Parameterization of electron beam output factor

Yuichi Akino, Timothy C. Zhu, Indra J. Das

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Electron beam dose distribution is dependent on the beam energy and complicated trajectory of particles. Recent treatment planning systems using Monte Carlo calculation algorithm provide accurate dose calculation. However, double check of monitor units (MUs) based on an independent algorithm is still required. In this study, we have demonstrated single equation that reproduces the measured relative output factor (ROF) that can be used for MU calculation for electron radiotherapy. Electron beams generated by an iX (Varian Medical Systems) and a PRIMUS (Siemens) accelerator were investigated. For various energies of electron beams, the ROF at respective d<inf>max</inf> were measured using diode detector in a water phantom at SSD of 100cm. Curve fitting was performed with an exponential generalized equation ROF= α(β - e<sup>-γR</sup>) including three variables (α, β, γ) as a function of field radius and electron energy. The correlation coefficients between the ROF measured and that calculated by the equation were greater than 0.998. For ROF of Varian electron beams, the average values of all fitting formulas were applied for two of the constants; α and β. The parameter γ showed good agreement with the quadratic approximation as a function of mean energy at surface (E<inf>0</inf>). The differences between measured and calculated ROF values were within ±3% for beams with cutout radius of ≥1.5cm for electron beams with energies from 6MeV to 15MeV. The proposed formula will be helpful for double-check of MUs, as it requires minimal efforts for MU calculation.

Original languageEnglish
Pages (from-to)420-424
Number of pages5
JournalPhysica Medica
Volume31
Issue number4
DOIs
StatePublished - Jun 1 2015

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parameterization
electron beams
Electrons
output
monitors
energy
Silver Sulfadiazine
dosage
radii
curve fitting
correlation coefficients
planning
radiation therapy
accelerators
Radiotherapy
diodes
trajectories
electron energy
Water
detectors

Keywords

  • Electron
  • Output factor
  • Parameterization

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging
  • Physics and Astronomy(all)

Cite this

Parameterization of electron beam output factor. / Akino, Yuichi; Zhu, Timothy C.; Das, Indra J.

In: Physica Medica, Vol. 31, No. 4, 01.06.2015, p. 420-424.

Research output: Contribution to journalArticle

Akino, Y, Zhu, TC & Das, IJ 2015, 'Parameterization of electron beam output factor', Physica Medica, vol. 31, no. 4, pp. 420-424. https://doi.org/10.1016/j.ejmp.2015.02.006
Akino, Yuichi ; Zhu, Timothy C. ; Das, Indra J. / Parameterization of electron beam output factor. In: Physica Medica. 2015 ; Vol. 31, No. 4. pp. 420-424.
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