Door gamma and neutron survey for TrueBEAM 10 MV with and without flattening filter free mode

Authors

  • Puntiwa Oonsiri Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society
  • Chulee Vannavijit Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society
  • Mananchaya Vimolnoch Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society
  • Nichakan Chatchumnan Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society
  • Sakda Kingkaew Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society

Keywords:

Radiation survey, Flattening filter free, Neutron dose

Abstract

Background: The photoneutron production from the interaction of the high energy photon exceeds 8 MV and high atomic number materials within gantry are undesired.

Objective: To perform the gamma and neutron survey behind the TrueBEAM door for both 10 MV and 10 FFF

Materials and Methods: The RadEYE GN+ from Thermo was used for neutron survey at the TrueBEAM treatment door for 10 MV and 10 FFF. The parameters that impact the peak neutron dose rate includes such as gantry angle, field size, and dose rate. The Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) treatment planning forboth conventional dose fractionation and the high dose per fraction like the Stereotactic Body Radiation Therapy (SBRT) were investigated in the gamma and neutron survey.

Results: The peak neutron dose rate was at 90° gantry angle that faced directly through the door. The 10 MV showed higher gamma and neutron peak dose rate. The smaller field size, higher dose rate, and higher MU technique like IMRT increased the gamma and neutron peak dose rate. SBRT technique gave higher dose fractionation and dose rate, thus, it had to higher neutron peak dose rate than the conventional fractionation.

Conclusion: The gamma and neutron peak dose rate through the TrueBEAM door depends on gantry angle, field size, flattening filter usage, dose rate, total number of MU, etc, however, the accumulated neutron dose for SBRT technique with 10 FFF was not detected.

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References

Banaee N, Goodarzi K, Nedaie HA. Neutron contamination in radiotherapy processes: a review study. J Radiat Res. 2021;62:947-54.

Montgomery L, Evans M, Liang L, Maglieri R, Kildea J. The effect of the flattening filter on photoneutron production at 10 MV in the Varian TrueBeam linear accelerator. Med Phys. 2018;45:4711-9.

Kry SF, Salehpour M, Followill DS, Stovall M, Kuban DA, White RA, et al. The calculated risk of fatal secondary malignancies from intensity-modulated radiation therapy. Int J Radiat Oncol Biol Phys. 2005;62:1195-203.

Polaczek-Grelik K, Karaczyn B, Konefal A. Nuclear reactions in linear medical accelerators and their exposure consequences. Appl Radiat Isot. 2012;70:2332-9.

พันทิวา อุณห์ศิริ. การประกันคุณภาพเครื่องฉายรังสี รุ่น TrueBEAM ด้วย วิธี Machine Performance Check (MPC). J Thai Assoc Radiat Oncol. 2018;24:45-52.

Georg D, Knöös T, McClean B. Current status and future perspective of flattening filter free photon beams. Med Phys. 2011;38:1280-93.

d'Errico F. Structural shielding design and evaluation for megavoltage x-and gamma-ray radiotherapy facilities: NCRP Report No. 151. USA; 2005.

Kry SF, Titt U, Pönisch F, Vassiliev ON, Salehpour M, Gillin M, et al. Reduced neutron production through use of a flattening-filter–free accelerator. Int J Radiat Oncol Biol Phys. 2007;68:1260-4.

Kuess P, Georg D, Palmans H, Lechner W. On the impact of the incident electron beam energy on the primary dose component of flattening filter free photon beams. Med Phys. 2016;43:4507-13.

Awikunprasert P, Tantivatana T, Pungkun V, Dachviriyakij T, Rangseevijitprapa R. Survey of photoneutron emitted from 6MV, 10MV, and 15MV medical LINAC using nuclear track detection. J Assoc Med Sci. 2021;55:45-51.

Published

2022-09-21

How to Cite

1.
Oonsiri P, Vannavijit C, Vimolnoch M, Chatchumnan N, Kingkaew S. Door gamma and neutron survey for TrueBEAM 10 MV with and without flattening filter free mode. J Thai Assn of Radiat Oncol [Internet]. 2022 Sep. 21 [cited 2022 Dec. 10];28(2):R1-R11. Available from: https://he01.tci-thaijo.org/index.php/jtaro/article/view/256547

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Original articles