The Measurement of Neutron Contamination in High Energy X-Ray Radiotherapy Using a He-3 Gas Dosimeter
Introduction: Neutron contamination is likely caused by the collision of high-energy photon interactions (γ, ṉ) with heavy metals used in the construction of the accelerator. This study is essential to quantify the excess dose from neutron contamination by Elekta Precis. The main object is to assess...
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Mashhad University of Medical Sciences
2024-10-01
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| Series: | Iranian Journal of Medical Physics |
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| Online Access: | https://ijmp.mums.ac.ir/article_23727_beb61096ba3445beb532c32e1f4c0fa5.pdf |
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| author | Alireza Vejdani Mehdi Momennezhad Sara Mohammadi Vajiheh Vejdani Noghreiyan Atefeh Rostami |
| author_facet | Alireza Vejdani Mehdi Momennezhad Sara Mohammadi Vajiheh Vejdani Noghreiyan Atefeh Rostami |
| author_sort | Alireza Vejdani |
| collection | DOAJ |
| description | Introduction: Neutron contamination is likely caused by the collision of high-energy photon interactions (γ, ṉ) with heavy metals used in the construction of the accelerator. This study is essential to quantify the excess dose from neutron contamination by Elekta Precis. The main object is to assess the neutron contamination with a gas dosimeter containing He-3.
Material and Methods: In this study, neutron contamination was estimated at different points in and out of the treatment room. We used two types of dosimeters: a He-3 gas dosimeter (CRAMAL 31) as a neutron dosimeter and Farmer ionization chambers, and PC-electrometer (Sun Nuclear, USA) which is sensitive to photons measured photo-neutron doses. Both the neutron and Farmer dosimeters were applied in the presence and absence of acrylic plates at the same point. In this study, Monte Carlo (MC) code was utilized to prepare the correct proportion of neutron dose.
Results: At different points in and out of the treatment room, neutron contamination was approximately in the range of background dose (D = 0.001 µSv). The neutron dosimeter displayed 48.792 µSv, 25.456 µSv and 28.756 µSv for 6, 10 and 15 MV photon energy, respectively. He-3 gas dosimeter showed that the neutron dose net was negligible under the treatment field.
Conclusion: He-3 gas dosimeter detected more than the usual neutron dose in 6 MV photon energy than we expected. Due to the high photon flux under the radiation fields, a He-3 neutron dosimeter reported photo-neutron dose. Nevertheless, the photo-neutron dose was in the range of micro Sievert (µSv). He-3 gas dosimeter was not suitable for neutron dosimetry in places with high photon fluence because of the low energy peak in the detection of neutrons. |
| format | Article |
| id | doaj-art-66a21528c3b24b54b056f683c457e8fa |
| institution | Kabale University |
| issn | 2345-3672 |
| language | English |
| publishDate | 2024-10-01 |
| publisher | Mashhad University of Medical Sciences |
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| series | Iranian Journal of Medical Physics |
| spelling | doaj-art-66a21528c3b24b54b056f683c457e8fa2025-01-18T07:29:18ZengMashhad University of Medical SciencesIranian Journal of Medical Physics2345-36722024-10-0121532933510.22038/ijmp.2024.75447.233223727The Measurement of Neutron Contamination in High Energy X-Ray Radiotherapy Using a He-3 Gas DosimeterAlireza Vejdani0Mehdi Momennezhad1Sara Mohammadi2Vajiheh Vejdani Noghreiyan3Atefeh Rostami4Physics Department, Faculty of Sciences, University of Neyshabur, Neyshabur, IranMedical Physics Department, Faculty of Medicine, Imam Reza Center of Medical Education and Treatment, Mashhad, IranMedical Physics Department, Faculty of Medicine, Gonabad University of Medical Sciences, Gonabad,IranMedical Physics and Radiological Sciences Department, Sabzevar University of Medical Sciencesdepartment of medical physics and radiological sciences, Sabzevar university of medical sciences, Sabzevar, IranIntroduction: Neutron contamination is likely caused by the collision of high-energy photon interactions (γ, ṉ) with heavy metals used in the construction of the accelerator. This study is essential to quantify the excess dose from neutron contamination by Elekta Precis. The main object is to assess the neutron contamination with a gas dosimeter containing He-3. Material and Methods: In this study, neutron contamination was estimated at different points in and out of the treatment room. We used two types of dosimeters: a He-3 gas dosimeter (CRAMAL 31) as a neutron dosimeter and Farmer ionization chambers, and PC-electrometer (Sun Nuclear, USA) which is sensitive to photons measured photo-neutron doses. Both the neutron and Farmer dosimeters were applied in the presence and absence of acrylic plates at the same point. In this study, Monte Carlo (MC) code was utilized to prepare the correct proportion of neutron dose. Results: At different points in and out of the treatment room, neutron contamination was approximately in the range of background dose (D = 0.001 µSv). The neutron dosimeter displayed 48.792 µSv, 25.456 µSv and 28.756 µSv for 6, 10 and 15 MV photon energy, respectively. He-3 gas dosimeter showed that the neutron dose net was negligible under the treatment field. Conclusion: He-3 gas dosimeter detected more than the usual neutron dose in 6 MV photon energy than we expected. Due to the high photon flux under the radiation fields, a He-3 neutron dosimeter reported photo-neutron dose. Nevertheless, the photo-neutron dose was in the range of micro Sievert (µSv). He-3 gas dosimeter was not suitable for neutron dosimetry in places with high photon fluence because of the low energy peak in the detection of neutrons.https://ijmp.mums.ac.ir/article_23727_beb61096ba3445beb532c32e1f4c0fa5.pdflinear acceleratordosimetryradiationneutron activation analysis |
| spellingShingle | Alireza Vejdani Mehdi Momennezhad Sara Mohammadi Vajiheh Vejdani Noghreiyan Atefeh Rostami The Measurement of Neutron Contamination in High Energy X-Ray Radiotherapy Using a He-3 Gas Dosimeter Iranian Journal of Medical Physics linear accelerator dosimetry radiation neutron activation analysis |
| title | The Measurement of Neutron Contamination in High Energy X-Ray Radiotherapy Using a He-3 Gas Dosimeter |
| title_full | The Measurement of Neutron Contamination in High Energy X-Ray Radiotherapy Using a He-3 Gas Dosimeter |
| title_fullStr | The Measurement of Neutron Contamination in High Energy X-Ray Radiotherapy Using a He-3 Gas Dosimeter |
| title_full_unstemmed | The Measurement of Neutron Contamination in High Energy X-Ray Radiotherapy Using a He-3 Gas Dosimeter |
| title_short | The Measurement of Neutron Contamination in High Energy X-Ray Radiotherapy Using a He-3 Gas Dosimeter |
| title_sort | measurement of neutron contamination in high energy x ray radiotherapy using a he 3 gas dosimeter |
| topic | linear accelerator dosimetry radiation neutron activation analysis |
| url | https://ijmp.mums.ac.ir/article_23727_beb61096ba3445beb532c32e1f4c0fa5.pdf |
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