### Abstract

The minimum size of a water phantom used for calibration of an epithermal neutron beam of the boron neutron capture therapy (BNCT) facility at the VTT FiR 1 research reactor is studied by Monte Carlo simulations. The criteria for the size of the phantom were established relative to the neutron and photon radiation fields present at the thermal neutron fluence maximum in the central beam axis (considered as the reference point). At the reference point, for the most commonly used beam aperture size at FiR 1 (14 cm diameter), less than 1% disturbance of the neutron and gamma radiation fields in a phantom were achieved with a minimum a 30 cm × 30 cm cross section of the phantom. For the largest 20 cm diameter beam aperture size, a minimum 40 cm × 40 cm cross-section of the phantom and depth of 20 cm was required to achieve undisturbed radiation field. This size can be considered as the minimum requirement for a reference phantom for dosimetry at FiR 1. The secondary objective was to determine the phantom dimensions for full characterization of the FiR 1 beam in a rectangular water phantom. In the water scanning phantom, isodoses down to the 5% level are measured for the verifications of the beam model in the dosimetric and treatment planning calculations. The dose distribution results without effects caused by the limited phantom size were achieved for the maximum aperture diameter (20 cm) with a 56 cm × 56 cm × 28 cm rectangular phantom. A similar approach to study the required minimum dimensions of the reference and water scanning phantoms can be used for epithermal neutron beams at the other BNCT facilities.

Original language | English |
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Pages (from-to) | N291-N300 |

Journal | Physics in Medicine and Biology |

Volume | 48 |

Issue number | 21 |

DOIs | |

Publication status | Published - 7 Nov 2003 |

MoE publication type | A1 Journal article-refereed |

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### Keywords

- dosimetry
- epithermal irradiation
- epithermal neutrons
- boron neutron capture therapy

### Cite this

*Physics in Medicine and Biology*,

*48*(21), N291-N300. https://doi.org/10.1088/0031-9155/48/21/N03

}

*Physics in Medicine and Biology*, vol. 48, no. 21, pp. N291-N300. https://doi.org/10.1088/0031-9155/48/21/N03

**Computational study of the required dimensions for standard sized phantoms boron neutron capture therapy dosimetry.** / Koivunoro, H.; Auterinen, I.; Kosunen, A.; Kotiluoto, P.; Seppaälä, T.; Savolainen, Sauli.

Research output: Contribution to journal › Article › Scientific › peer-review

TY - JOUR

T1 - Computational study of the required dimensions for standard sized phantoms boron neutron capture therapy dosimetry

AU - Koivunoro, H.

AU - Auterinen, I.

AU - Kosunen, A.

AU - Kotiluoto, P.

AU - Seppaälä, T.

AU - Savolainen, Sauli

PY - 2003/11/7

Y1 - 2003/11/7

N2 - The minimum size of a water phantom used for calibration of an epithermal neutron beam of the boron neutron capture therapy (BNCT) facility at the VTT FiR 1 research reactor is studied by Monte Carlo simulations. The criteria for the size of the phantom were established relative to the neutron and photon radiation fields present at the thermal neutron fluence maximum in the central beam axis (considered as the reference point). At the reference point, for the most commonly used beam aperture size at FiR 1 (14 cm diameter), less than 1% disturbance of the neutron and gamma radiation fields in a phantom were achieved with a minimum a 30 cm × 30 cm cross section of the phantom. For the largest 20 cm diameter beam aperture size, a minimum 40 cm × 40 cm cross-section of the phantom and depth of 20 cm was required to achieve undisturbed radiation field. This size can be considered as the minimum requirement for a reference phantom for dosimetry at FiR 1. The secondary objective was to determine the phantom dimensions for full characterization of the FiR 1 beam in a rectangular water phantom. In the water scanning phantom, isodoses down to the 5% level are measured for the verifications of the beam model in the dosimetric and treatment planning calculations. The dose distribution results without effects caused by the limited phantom size were achieved for the maximum aperture diameter (20 cm) with a 56 cm × 56 cm × 28 cm rectangular phantom. A similar approach to study the required minimum dimensions of the reference and water scanning phantoms can be used for epithermal neutron beams at the other BNCT facilities.

AB - The minimum size of a water phantom used for calibration of an epithermal neutron beam of the boron neutron capture therapy (BNCT) facility at the VTT FiR 1 research reactor is studied by Monte Carlo simulations. The criteria for the size of the phantom were established relative to the neutron and photon radiation fields present at the thermal neutron fluence maximum in the central beam axis (considered as the reference point). At the reference point, for the most commonly used beam aperture size at FiR 1 (14 cm diameter), less than 1% disturbance of the neutron and gamma radiation fields in a phantom were achieved with a minimum a 30 cm × 30 cm cross section of the phantom. For the largest 20 cm diameter beam aperture size, a minimum 40 cm × 40 cm cross-section of the phantom and depth of 20 cm was required to achieve undisturbed radiation field. This size can be considered as the minimum requirement for a reference phantom for dosimetry at FiR 1. The secondary objective was to determine the phantom dimensions for full characterization of the FiR 1 beam in a rectangular water phantom. In the water scanning phantom, isodoses down to the 5% level are measured for the verifications of the beam model in the dosimetric and treatment planning calculations. The dose distribution results without effects caused by the limited phantom size were achieved for the maximum aperture diameter (20 cm) with a 56 cm × 56 cm × 28 cm rectangular phantom. A similar approach to study the required minimum dimensions of the reference and water scanning phantoms can be used for epithermal neutron beams at the other BNCT facilities.

KW - dosimetry

KW - epithermal irradiation

KW - epithermal neutrons

KW - boron neutron capture therapy

UR - http://www.scopus.com/inward/record.url?scp=0242606106&partnerID=8YFLogxK

U2 - 10.1088/0031-9155/48/21/N03

DO - 10.1088/0031-9155/48/21/N03

M3 - Article

C2 - 14653569

AN - SCOPUS:0242606106

VL - 48

SP - N291-N300

JO - Physics in Medicine and Biology

JF - Physics in Medicine and Biology

SN - 0031-9155

IS - 21

ER -