<abstract xmlns="http://www.w3.org/1999/xhtml"><sec id="j_raon-2020-0024_s_006_w2aab3b7c56b1b6b1aab1c16b1Aa"><h3>Background</h3><p>High energy electron linear accelerators (LINACs) producing photon beams with energies higher than 10 MeV are widely used in radiation therapy. In these beams, fast neutrons are generated, which results in undesired contamination of the therapeutic beam. In this study, measurements and Monte Carlo (MC) simulations were used to obtain neutron spectra and dose equivalents in vicinity of linear accelerator.</p></sec><sec id="j_raon-2020-0024_s_007_w2aab3b7c56b1b6b1aab1c16b2Aa"><h3>Materials and methods</h3><p>LINAC Siemens Oncor Expression in Osijek University Hospital is placed in vault that was previously used for <sup>60</sup>Co machine. Then, the shielding of the vault was enhanced using lead and steel plates. Measurements of neutron dose equivalent around LINAC and the vault were done using CR-39 solid state nuclear track detectors. To compensate energy dependence of detectors, neutron energy spectra was calculated in measuring positions using MC simulations.</p></sec><sec id="j_raon-2020-0024_s_008_w2aab3b7c56b1b6b1aab1c16b3Aa"><h3>Results</h3><p>The vault is a source of photoneutrons, but a vast majority of neutrons originates from accelerator head. Neutron spectra obtained from MC simulations show significant changes between the measuring positions. Annual neutron dose equivalent per year was estimated to be less than 324 μSv in the measuring points outside of the vault.</p></sec><sec id="j_raon-2020-0024_s_009_w2aab3b7c56b1b6b1aab1c16b4Aa"><h3>Conclusions</h3><p>Since detectors used in this paper are very dependent on neutron energy, it is extremely important to know the neutron spectra in measuring points. Though, patient dosimetry should include neutrons, estimated annual neutron doses outside the vault were far below exposure limit of ionizing radiation for workers.</p></sec></abstract>

BackgroundHigh energy electron linear accelerators (LINACs) producing photon beams with energies higher than 10 MeV are widely used in radiation therapy. In these beams, fast neutrons are generated, which results in undesired contamination of the therapeutic beam. In this study, measurements and Monte Carlo (MC) simulations were used to obtain neutron spectra and dose equivalents in vicinity of linear accelerator.Materials and methodsLINAC Siemens Oncor Expression in Osijek University Hospital is placed in vault that was previously used for 60Co machine. Then, the shielding of the vault was enhanced using lead and steel plates. Measurements of neutron dose equivalent around LINAC and the vault were done using CR-39 solid state nuclear track detectors. To compensate energy dependence of detectors, neutron energy spectra was calculated in measuring positions using MC simulations.ResultsThe vault is a source of photoneutrons, but a vast majority of neutrons originates from accelerator head. Neutron spectra obtained from MC simulations show significant changes between the measuring positions. Annual neutron dose equivalent per year was estimated to be less than 324 μSv in the measuring points outside of the vault.ConclusionsSince detectors used in this paper are very dependent on neutron energy, it is extremely important to know the neutron spectra in measuring points. Though, patient dosimetry should include neutrons, estimated annual neutron doses outside the vault were far below exposure limit of ionizing radiation for workers.

The influence of shielding reinforcement in a vault with limited dimensions on the neutron dose equivalent in vicinity of medical electron linear accelerator

Radiology and Oncology

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BackgroundHigh energy electron linear accelerators (LINACs) producing photon beams with energies higher than 10 MeV are widely used in radiation therapy. In...

The influence of shielding reinforcement in a vault with limited dimensions on the neutron dose equivalent in vicinity of medical electron linear accelerator

Article Category: Research Article

Publicado en línea: 02 may 2020

Páginas: 247 - 252

Recibido: 02 feb 2020

Aceptado: 11 mar 2020

DOI: https://doi.org/10.2478/raon-2020-0024

© 2020 Ana Ivkovic, Dario Faj, Mladen Kasabasic, Marina Poje Sovilj, Ivana Krpan, Marina Grabar Branilovic, Hrvoje Brkic, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.