### Abstract

Clinical electron beams contain an admixture of bremsstrahlung produced in structures in the accelerator head, in field-defining cerrobend or lead cutouts, and in the irradiated patient or water phantom. Accurate knowledge of these components is important for dose calculations and treatment planning. In this study, the bremsstrahlung components are separated for electron beams (energy 6-22 MeV, diameter 0-5 cm) using measurements in water and calculations. The results show that bremsstrahlung from the accelerator head dominates and increases with field size for electron beams generated by accelerators equipped with scattering foils. The bremsstrahlung from the field-defining cerrobend accounts for 10% to 30% of the total bremsstrahlung and decreases with increasing beam radius. The bremsstrahlung is softer than the x-ray beams of corresponding nominal energy since the latter are hardened by the flattening filter. For the 6, 12, and 22 MeV electron beams, the effective attenuation coefficients in water for the bremsstrahlung are 0.058, 0.050, and 0.043 cm^{-1}. The depths of maximum dose at 100 cm SSD are 0.8, 1.7, and 3.0 cm. The position of the virtual source of the bremsstrahlung shifts downstream from the nominal source position by 20, 13, 5.6 cm, respectively. The lateral bremsstrahlung dose distribution is more forward-peaked for higher electron energy. The bremsstrahlung components could be described for any machine by a set of simple measurements and can be modeled by an analytical expression.

Original language | English (US) |
---|---|

Pages (from-to) | 1352-1358 |

Number of pages | 7 |

Journal | Medical Physics |

Volume | 28 |

Issue number | 7 |

DOIs | |

State | Published - 2001 |

Externally published | Yes |

### Fingerprint

### Keywords

- Bremsstrahlung
- Electron beam
- Monte Carlo
- Radiotherapy

### ASJC Scopus subject areas

- Biophysics

### Cite this

*Medical Physics*,

*28*(7), 1352-1358. https://doi.org/10.1118/1.1382608

**Characteristics of bremsstrahlung in electron beams.** / Zhu, T. C.; Das, I. J.; Bjärngard, B. E.

Research output: Contribution to journal › Article

*Medical Physics*, vol. 28, no. 7, pp. 1352-1358. https://doi.org/10.1118/1.1382608

}

TY - JOUR

T1 - Characteristics of bremsstrahlung in electron beams

AU - Zhu, T. C.

AU - Das, I. J.

AU - Bjärngard, B. E.

PY - 2001

Y1 - 2001

N2 - Clinical electron beams contain an admixture of bremsstrahlung produced in structures in the accelerator head, in field-defining cerrobend or lead cutouts, and in the irradiated patient or water phantom. Accurate knowledge of these components is important for dose calculations and treatment planning. In this study, the bremsstrahlung components are separated for electron beams (energy 6-22 MeV, diameter 0-5 cm) using measurements in water and calculations. The results show that bremsstrahlung from the accelerator head dominates and increases with field size for electron beams generated by accelerators equipped with scattering foils. The bremsstrahlung from the field-defining cerrobend accounts for 10% to 30% of the total bremsstrahlung and decreases with increasing beam radius. The bremsstrahlung is softer than the x-ray beams of corresponding nominal energy since the latter are hardened by the flattening filter. For the 6, 12, and 22 MeV electron beams, the effective attenuation coefficients in water for the bremsstrahlung are 0.058, 0.050, and 0.043 cm-1. The depths of maximum dose at 100 cm SSD are 0.8, 1.7, and 3.0 cm. The position of the virtual source of the bremsstrahlung shifts downstream from the nominal source position by 20, 13, 5.6 cm, respectively. The lateral bremsstrahlung dose distribution is more forward-peaked for higher electron energy. The bremsstrahlung components could be described for any machine by a set of simple measurements and can be modeled by an analytical expression.

AB - Clinical electron beams contain an admixture of bremsstrahlung produced in structures in the accelerator head, in field-defining cerrobend or lead cutouts, and in the irradiated patient or water phantom. Accurate knowledge of these components is important for dose calculations and treatment planning. In this study, the bremsstrahlung components are separated for electron beams (energy 6-22 MeV, diameter 0-5 cm) using measurements in water and calculations. The results show that bremsstrahlung from the accelerator head dominates and increases with field size for electron beams generated by accelerators equipped with scattering foils. The bremsstrahlung from the field-defining cerrobend accounts for 10% to 30% of the total bremsstrahlung and decreases with increasing beam radius. The bremsstrahlung is softer than the x-ray beams of corresponding nominal energy since the latter are hardened by the flattening filter. For the 6, 12, and 22 MeV electron beams, the effective attenuation coefficients in water for the bremsstrahlung are 0.058, 0.050, and 0.043 cm-1. The depths of maximum dose at 100 cm SSD are 0.8, 1.7, and 3.0 cm. The position of the virtual source of the bremsstrahlung shifts downstream from the nominal source position by 20, 13, 5.6 cm, respectively. The lateral bremsstrahlung dose distribution is more forward-peaked for higher electron energy. The bremsstrahlung components could be described for any machine by a set of simple measurements and can be modeled by an analytical expression.

KW - Bremsstrahlung

KW - Electron beam

KW - Monte Carlo

KW - Radiotherapy

UR - http://www.scopus.com/inward/record.url?scp=0034919013&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034919013&partnerID=8YFLogxK

U2 - 10.1118/1.1382608

DO - 10.1118/1.1382608

M3 - Article

C2 - 11488565

AN - SCOPUS:0034919013

VL - 28

SP - 1352

EP - 1358

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 7

ER -