Joint EURADOS WG9-WG11 rem-counter intercomparison in a Mevion S250i proton therapy facility with Hyperscan pulsed synchrocyclotron
| Autor: | Gabriele Zorloni, Geert Bosmans, Thomas Brall, Marco Caresana, Marijke De Saint-Hubert, Carles Domingo, Christian Ferrante, Francesca Ferrulli, Renata Kopec, Johannes Leidner, Vladimir Mares, Racell Nabha, Pawel Olko, Miguel Angel Caballero-Pacheco, Werner Rühm, Marco Silari, Liliana Stolarczyk, null Jan Swakon, Marco Tisi, Sebastian Trinkl, Olivier Van Hoey, Gloria Vilches-Freixas |
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| Přispěvatelé: | RS: GROW - R3 - Innovative Cancer Diagnostics & Therapy, Maastro clinic |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
dosimetry at accelerators
RISK Health Physics and Radiation Effects Technology Science & Technology INSTRUMENT Radiological and Ultrasound Technology RANGE Radiology Nuclear Medicine & Medical Imaging DOSIMETRY neutron dosimetry Dosimetry At Accelerators Neutron Dosimetry Pulsed Field Dosimetry Rem-counter Engineering SPECTROMETRY RADIATION-THERAPY rem-counter NEUTRON FLUENCE pulsed field dosimetry Radiology Nuclear Medicine and imaging LINUS FIELD Life Sciences & Biomedicine Engineering Biomedical SYSTEM |
| Zdroj: | Physics in Medicine and Biology, 67(7):075005. IOP Publishing Ltd. Phys. Med. Biol. 67:075005 (2022) |
| ISSN: | 0031-9155 |
| DOI: | 10.1088/1361-6560/ac5b9c |
| Popis: | Objective. Proton therapy is gaining popularity because of the improved dose delivery over conventional radiation therapy. The secondary dose to healthy tissues is dominated by secondary neutrons. Commercial rem-counters are valuable instruments for the on-line assessment of neutron ambient dose equivalent (H*(10)). In general, however, a priori knowledge of the type of facility and of the radiation field is required for the proper choice of any survey meter. The novel Mevion S250i Hyperscan synchrocyclotron mounts the accelerator directly on the gantry. It provides a scanned 227 MeV proton beam, delivered in pulses with a pulse width of 10 μs at 750 Hz frequency, which is afterwards degraded in energy by a range shifter modulator system. This environment is particularly challenging for commercial rem-counters; therefore, we tested the reliability of some of the most widespread rem-counters to understand their limits in the Mevion S250i stray neutron field. Approach. This work, promoted by the European Radiation Dosimetry Group (EURADOS), describes a rem-counter intercomparison at the Maastro Proton Therapy centre in the Netherlands, which houses the novel Mevion S250i Hyperscan system. Several rem-counters were employed in the intercomparison (LUPIN, LINUS, WENDI-II, LB6411, NM2B-458, NM2B-495Pb), which included simulation of a patient treatment protocol employing a water tank phantom. The outcomes of the experiment were compared with models and data from the literature. Main results. We found that only the LUPIN allowed for a correct assessment of H*(10) within a 20% uncertainty. All other rem-counters underestimated the reference H*(10) by factors from 2 to more than 10, depending on the detector model and on the neutron dose per pulse. In pulsed fields, the neutron dose per pulse is a fundamental parameter, while the average neutron dose rate is a secondary quantity. An average 150–200 μSv/GyRBE neutron H*(10) at various positions around the phantom and at distances between 186 cm and 300 cm from it was measured per unit therapeutic dose delivered to the target. Significance. Our results are partially in line with results obtained at similar Mevion facilities employing passive energy modulation. Comparisons with facilities employing active energy modulation confirmed that the neutron H*(10) can increase up to more than a factor of 10 when passive energy modulation is employed. The challenging environment of the Mevion stray neutron field requires the use of specific rem-counters sensitive to high-energy neutrons (up to a few hundred MeV) and specifically designed to withstand pulsed neutron fields. |
| Databáze: | OpenAIRE |
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