### 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 language | English |
---|---|

Pages (from-to) | 420-424 |

Number of pages | 5 |

Journal | Physica Medica |

Volume | 31 |

Issue number | 4 |

DOIs | |

State | Published - Jun 1 2015 |

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### Keywords

- Electron
- Output factor
- Parameterization

### ASJC Scopus subject areas

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

### Cite this

*Physica Medica*,

*31*(4), 420-424. https://doi.org/10.1016/j.ejmp.2015.02.006

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

Research output: Contribution to journal › Article

*Physica Medica*, vol. 31, no. 4, pp. 420-424. https://doi.org/10.1016/j.ejmp.2015.02.006

}

TY - JOUR

T1 - Parameterization of electron beam output factor

AU - Akino, Yuichi

AU - Zhu, Timothy C.

AU - Das, Indra J.

PY - 2015/6/1

Y1 - 2015/6/1

N2 - 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 dmax 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-γR) 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 (E0). 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.

AB - 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 dmax 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-γR) 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 (E0). 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.

KW - Electron

KW - Output factor

KW - Parameterization

UR - http://www.scopus.com/inward/record.url?scp=84928436115&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84928436115&partnerID=8YFLogxK

U2 - 10.1016/j.ejmp.2015.02.006

DO - 10.1016/j.ejmp.2015.02.006

M3 - Article

C2 - 25726475

AN - SCOPUS:84928436115

VL - 31

SP - 420

EP - 424

JO - Physica Medica

JF - Physica Medica

SN - 1120-1797

IS - 4

ER -