Experimental validation of an analytical program and a Monte Carlo simulation for the computation of the far out-of-field dose in external beam photon therapy applied to pediatric patients

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• dc.contributor.author De Saint-Hubert, Marijke
• dc.contributor.author Suesselbeck, Finja
• dc.contributor.author Vasi, Fabiano
• dc.contributor.author Stuckmann, Florian
• dc.contributor.author Rodriguez, Miguel
• dc.contributor.author Dabin, Jérémie
• dc.contributor.author Timmermann, Beate
• dc.contributor.author Thierry-Chef, Isabelle
• dc.contributor.author Schneider, Uwe
• dc.contributor.author Brualla, Lorenzo
• dc.date.accessioned 2022-12-02T07:11:22Z
• dc.date.available 2022-12-02T07:11:22Z
• dc.date.issued 2022
• dc.description.abstract Background: The out-of-the-field absorbed dose affects the probability of primary second radiation-induced cancers. This is particularly relevant in the case of pediatric treatments. There are currently no methods employed in the clinical routine for the computation of dose distributions from stray radiation in radiotherapy. To overcome this limitation in the framework of conventional teletherapy with photon beams, two computational tools have been developed-one based on an analytical approach and another depending on a fast Monte Carlo algorithm. The purpose of this work is to evaluate the accuracy of these approaches by comparison with experimental data obtained from anthropomorphic phantom irradiations. Materials and methods: An anthropomorphic phantom representing a 5-year-old child (ATOM, CIRS) was irradiated considering a brain tumor using a Varian TrueBeam linac. Two treatments for the same planned target volume (PTV) were considered, namely, intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). In all cases, the irradiation was conducted with a 6-MV energy beam using the flattening filter for a prescribed dose of 3.6 Gy to the PTV. The phantom had natLiF : Mg, Cu, P (MCP-N) thermoluminescent dosimeters (TLDs) in its 180 holes. The uncertainty of the experimental data was around 20%, which was mostly attributed to the MCP-N energy dependence. To calculate the out-of-field dose, an analytical algorithm was implemented to be run from a Varian Eclipse TPS. This algorithm considers that all anatomical structures are filled with water, with the exception of the lungs which are made of air. The fast Monte Carlo code dose planning method was also used for computing the out-of-field dose. It was executed from the dose verification system PRIMO using a phase-space file containing 3x109 histories, reaching an average standard statistical uncertainty of less than 0.2% (coverage factor k = 1 ) on all voxels scoring more than 50% of the maximum dose. The standard statistical uncertainty of out-of-field voxels in the Monte Carlo simulation did not exceed 5%. For the Monte Carlo simulation the actual chemical composition of the materials used in ATOM, as provided by the manufacturer, was employed. Results: In the out-of-the-field region, the absorbed dose was on average four orders of magnitude lower than the dose at the PTV. For the two modalities employed, the discrepancy between the central values of the TLDs located in the out-of-the-field region and the corresponding positions in the analytic model were in general less than 40%. The discrepancy in the lung doses was more pronounced for IMRT. The same comparison between the experimental and the Monte Carlo data yielded differences which are, in general, smaller than 20%. It was observed that the VMAT irradiation produces the smallest out-of-the-field dose when compared to IMRT. Conclusions: The proposed computational methods for the routine calculation of the out-of-the-field dose produce results that are similar, in most cases, with the experimental data. It has been experimentally found that the VMAT irradiation produces the smallest out-of-the-field dose when compared to IMRT for a given PTV.
• dc.description.sponsorship The presented research has been funded by the HARMONIC project. The HARMONIC project (Health effects of cArdiac fluoRoscopy and MOderN radIotherapy in paediatriCs) has received funding from the Euratom research and training programme 2014-2018 under grant agreement number 847707. MR acknowledges funding from the Sistema Nacional de Investigación de Panamá. ITC acknowledges support from the Spanish Ministry of Science and Innovation and State Research Agency through the “Centro de Excelencia Severo Ochoa 2019-2023” Program (CEX2018-000806-S) and support from the Generalitat de Catalunya through the CERCA Program.
• dc.format.mimetype application/pdf
• dc.identifier.citation De Saint-Hubert M, Suesselbeck F, Vasi F, Stuckmann F, Rodriguez M, Dabin J, Timmermann B, Thierry-Chef I, Schneider U, Brualla L. Experimental validation of an analytical program and a Monte Carlo simulation for the computation of the far out-of-field dose in external beam photon therapy applied to pediatric patients. Front Oncol. 2022 Jul 7;12:882506. DOI: 10.3389/fonc.2022.882506
• dc.identifier.doi http://dx.doi.org/10.3389/fonc.2022.882506
• dc.identifier.issn 2234-943X
• dc.identifier.uri http://hdl.handle.net/10230/55072
• dc.language.iso eng
• dc.publisher Frontiers
• dc.relation.ispartof Front Oncol. 2022 Jul 7;12:882506
• dc.relation.projectID info:eu-repo/grantAgreement/EC/H2020/847707
• dc.rights © 2022 De Saint-Hubert, Suesselbeck, Vasi, Stuckmann, Rodriguez, Dabin, Timmermann, Thierry-Chef, Schneider and Brualla. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
• dc.rights.accessRights info:eu-repo/semantics/openAccess
• dc.rights.uri http://creativecommons.org/licenses/by/4.0/
• dc.subject.keyword Monte Carlo
• dc.subject.keyword PRIMO
• dc.subject.keyword TLD
• dc.subject.keyword Analytical model
• dc.subject.keyword Anthropomorphic
• dc.subject.keyword Pediatric
• dc.subject.keyword Photon
• dc.subject.keyword Teletherapy
• dc.title Experimental validation of an analytical program and a Monte Carlo simulation for the computation of the far out-of-field dose in external beam photon therapy applied to pediatric patients
• dc.type info:eu-repo/semantics/article
• dc.type.version info:eu-repo/semantics/publishedVersion