Abstract
AB006. A photon isoeffective brain dose model for boron neutron capture therapy based on dose-response assessment from an animal model and its impact on a retrospective analysis of glioblastoma treatment
Ana Mailén Dattoli Viegas1,2, Daniel Carando1,3, Hanna Koivunoro4,5, Heikki Joensuu5, Sara González1,2
1National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina;
2Department of Boron Neutron Capture Therapy, National Atomic Energy Commission (CNEA), Buenos Aires, Argentina;
3Department of Mathematics, Faculty of Exact and Natural Sciences, University of Buenos Aires (UBA), Buenos Aires, Argentina;
4Neutron Therapeutics, Helsinki, Finland;
5Department of Oncology, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
Correspondence to: Ana Mailén Dattoli Viegas, B.Sc. in Physics. National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina; Department of Boron Neutron Capture Therapy, National Atomic Energy Commission (CNEA), Av. Gral. Paz 1499, B1650 Villa Maipú, Buenos Aires, Argentina. Email: mailendattoli@gmail.com; anadattoli@integra.cnea.gob.ar.
Background: In a clinical protocol, the dose administered to the organs at risk imposes a limit to treatment time, and thus, to tumor dose. The brain is a major dose-limiting organ for brain cancer patients undergoing radiotherapy. An adequate estimation of the dose to this organ is essential to minimize the potential adverse effects. In boron neutron capture therapy (BNCT), a mixed radiation field is produced in which the absorbed dose does not directly reflect the observed biological effect. Therefore, a dose model is needed to translate the different BNCT components into an equivalent dose. A common approach is to use the “relative biological effectiveness (RBE)-weighted” dose model. However, this has been shown to overestimate the photon-equivalent dose in tumors and underestimate it in normal tissue. The concept of photon isoeffective dose model was found suitable for describing the BNCT dose in photon-equivalent units for different tissues. This work aims to develop a photon isoeffective dose model for the brain that accurately reflects BNCT effects in terms of photon radiotherapy.
Methods: In this work, we developed a model for calculating photon isoeffective doses for the normal brain, based on the radiotoxic effects reported for an in vivo small animal model subjected to photon and BNCT irradiation. We proposed suitable mathematical expressions to describe the normal tissue complication probability (NTCP) for the reference photon radiation and for BNCT, which allowed us to derive the first model to obtain the photon dose that produces the same probability of brain toxicity as the BNCT treatment.
Results: We derived the photon isoeffective dose model for the normal brain and applied the developed model for dose calculation in BNCT treatments of malignant gliomas performed in Finland. The calculated doses, compared with adverse tissue reactions expected from conventional radiotherapy, allow us to assess whether the doses are representative of the radiotoxic effects observed in clinical BNCT. We found that the normal brain doses derived from our model are higher than those obtained with the standard model.
Conclusions: The brain doses calculated using the photon isoeffective dose model offer a more accurate representation of the radiotoxic effects observed in the clinical BNCT.
Keywords: Photon isoeffective dose; glioblastoma; normal tissue complication probability (NTCP)
Acknowledgments
None.
Funding: None.
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tro.amegroups.com/article/view/10.21037/tro-2025-ab006/coif). H.K. serves as an unpaid editorial board member of Therapeutic Radiology and Oncology from October 2024 to December 2026. A.M.D.V. and S.G. are employees of the CONICET and CNEA. D.C. is an employee of the CONICE. H.K. is an employee of the Neutron Therapeutics. The other author has no conflicts of interest to declare.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The approval was not required as the clinical data evaluated in this study had already been published.
Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the noncommercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.
doi: 10.21037/tro-25-ab006
Cite this abstract as: Viegas AMD, Carando D, Koivunoro H, Joensuu H, González S. AB006. A photon isoeffective brain dose model for boron neutron capture therapy based on dose-response assessment from an animal model and its impact on a retrospective analysis of glioblastoma treatment. Ther Radiol Oncol 2025;9:AB006.
