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Mares V, Farah J, De Saint-Hubert M, Domański S, Domingo C, Dommert M, Kłodowska M, Krzempek K, Kuć M, Martínez-Rovira I, Michaś E, Mojżeszek N, Murawski Ł, Ploc O, Romero-Expósito M, Tisi M, Trompier F, Van Hoey O, Van Ryckeghem L, Wielunski M, Harrison RM, Stolarczyk L, Olko P. Neutron Radiation Dose Measurements in a Scanning Proton Therapy Room: Can Parents Remain Near Their Children During Treatment? Front Oncol 2022; 12:903706. [PMID: 35912238 PMCID: PMC9330633 DOI: 10.3389/fonc.2022.903706] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 05/16/2022] [Indexed: 11/15/2022] Open
Abstract
Purpose This study aims to characterize the neutron radiation field inside a scanning proton therapy treatment room including the impact of different pediatric patient sizes. Materials and Methods Working Group 9 of the European Radiation Dosimetry Group (EURADOS) has performed a comprehensive measurement campaign to measure neutron ambient dose equivalent, H*(10), at eight different positions around 1-, 5-, and 10-year-old pediatric anthropomorphic phantoms irradiated with a simulated brain tumor treatment. Several active detector systems were used. Results The neutron dose mapping within the gantry room showed that H*(10) values significantly decreased with distance and angular deviation with respect to the beam axis. A maximum value of about 19.5 µSv/Gy was measured along the beam axis at 1 m from the isocenter for a 10-year-old pediatric phantom at 270° gantry angle. A minimum value of 0.1 µSv/Gy was measured at a distance of 2.25 m perpendicular to the beam axis for a 1-year-old pediatric phantom at 140° gantry angle. The H*(10) dependence on the size of the pediatric patient was observed. At 270° gantry position, the measured neutron H*(10) values for the 10-year-old pediatric phantom were up to 20% higher than those measured for the 5-year-old and up to 410% higher than for the 1-year-old phantom, respectively. Conclusions Using active neutron detectors, secondary neutron mapping was performed to characterize the neutron field generated during proton therapy of pediatric patients. It is shown that the neutron ambient dose equivalent H*(10) significantly decreases with distance and angle with respect to the beam axis. It is reported that the total neutron exposure of a person staying at a position perpendicular to the beam axis at a distance greater than 2 m from the isocenter remains well below the dose limit of 1 mSv per year for the general public (recommended by the International Commission on Radiological Protection) during the entire treatment course with a target dose of up to 60 Gy. This comprehensive analysis is key for general neutron shielding issues, for example, the safe operation of anesthetic equipment. However, it also enables the evaluation of whether it is safe for parents to remain near their children during treatment to bring them comfort. Currently, radiation protection protocols prohibit the occupancy of the treatment room during beam delivery.
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Affiliation(s)
- Vladimir Mares
- Helmholtz Zentrum München, Institute of Radiation Medicine, Neuherberg, Germany
- *Correspondence: Vladimir Mares,
| | - Jad Farah
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-Santé, Fontenay-aux-Roses, France
| | - Marijke De Saint-Hubert
- Belgian Nuclear Research Center, (SCK CEN), Institute for Environment, Health and Safety (EHS), Mol, Belgium
| | - Szymon Domański
- National Centre for Nuclear Research, Radiological Metrology and Biomedical Physics Division, Otwock-Świerk, Poland
| | - Carles Domingo
- Departament de Física, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Martin Dommert
- Helmholtz Zentrum München, Institute of Radiation Medicine, Neuherberg, Germany
| | - Magdalena Kłodowska
- Cambridge University Hospital National Health Service (NHS) Trust, Medical Physics, Cambridge, United Kingdom
| | - Katarzyna Krzempek
- Institute of Nuclear Physics, Polish Academy of Sciences, (IFJ PAN), Krakow, Poland
| | - Michał Kuć
- National Centre for Nuclear Research, Radiological Metrology and Biomedical Physics Division, Otwock-Świerk, Poland
| | | | - Edyta Michaś
- National Centre for Nuclear Research, Radiological Metrology and Biomedical Physics Division, Otwock-Świerk, Poland
| | - Natalia Mojżeszek
- Institute of Nuclear Physics, Polish Academy of Sciences, (IFJ PAN), Krakow, Poland
| | - Łukasz Murawski
- National Centre for Nuclear Research, Radiological Metrology and Biomedical Physics Division, Otwock-Świerk, Poland
| | - Ondrej Ploc
- Department of Radiation Dosimetry, Nuclear Physics Institute of the Czech Academy of Sciences (CAS), Prague, Czechia
| | | | - Marco Tisi
- Helmholtz Zentrum München, Institute of Radiation Medicine, Neuherberg, Germany
| | - François Trompier
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-Santé, Fontenay-aux-Roses, France
| | - Olivier Van Hoey
- Belgian Nuclear Research Center, (SCK CEN), Institute for Environment, Health and Safety (EHS), Mol, Belgium
| | - Laurent Van Ryckeghem
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-Santé, Fontenay-aux-Roses, France
| | - Marek Wielunski
- Helmholtz Zentrum München, Institute of Radiation Medicine, Neuherberg, Germany
| | - Roger M. Harrison
- Faculty of Medical Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Liliana Stolarczyk
- Institute of Nuclear Physics, Polish Academy of Sciences, (IFJ PAN), Krakow, Poland
- Danish Centre for Particle Therapy, Aarhus University Hospital (AUH), Aarhus, Denmark
| | - Pawel Olko
- Institute of Nuclear Physics, Polish Academy of Sciences, (IFJ PAN), Krakow, Poland
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Mares V, Romero-Expósito M, Farah J, Trinkl S, Domingo C, Dommert M, Stolarczyk L, Van Ryckeghem L, Wielunski M, Olko P, Harrison RM. A comprehensive spectrometry study of a stray neutron radiation field in scanning proton therapy. Phys Med Biol 2016; 61:4127-40. [PMID: 27171358 DOI: 10.1088/0031-9155/61/11/4127] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The purpose of this study is to characterize the stray neutron radiation field in scanning proton therapy considering a pediatric anthropomorphic phantom and a clinically-relevant beam condition. Using two extended-range Bonner sphere spectrometry systems (ERBSS), Working Group 9 of the European Radiation Dosimetry Group measured neutron spectra at ten different positions around a pediatric anthropomorphic phantom irradiated for a brain tumor with a scanning proton beam. This study compares the different systems and unfolding codes as well as neutron spectra measured in similar conditions around a water tank phantom. The ten spectra measured with two ERBSS systems show a generally similar thermal component regardless of the position around the phantom while high energy neutrons (above 20 MeV) were only registered at positions near the beam axis (at 0°, 329° and 355°). Neutron spectra, fluence and ambient dose equivalent, H (*)(10), values of both systems were in good agreement (<15%) while the unfolding code proved to have a limited effect. The highest H (*)(10) value of 2.7 μSv Gy(-1) was measured at 329° to the beam axis and 1.63 m from the isocenter where high-energy neutrons (E ⩾ 20 MeV) contribute with about 53%. The neutron mapping within the gantry room showed that H (*)(10) values significantly decreased with distance and angular position with respect to the beam axis dropping to 0.52 μSv Gy(-1) at 90° and 3.35 m. Spectra at angles of 45° and 135° with respect to the beam axis measured here with an anthropomorphic phantom showed a similar peak structure at the thermal, fast and high energy range as in the previous water-tank experiments. Meanwhile, at 90°, small differences at the high-energy range were observed. Using ERBSS systems, neutron spectra mapping was performed to characterize the exposure of scanning proton therapy patients. The ten measured spectra provide precise information about the exposure of healthy organs to thermal, epithermal, evaporation and intra-nuclear cascade neutrons. This comprehensive spectrometry analysis can also help in understanding the tremendous literature data based rem-counters while also being of great value for general neutron shielding and radiation safety studies.
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Affiliation(s)
- Vladimir Mares
- Helmholtz Zentrum München, Institute of Radiation Protection, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
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