Microdosimetry of an accelerator based thermal neutron field for Boron Neutron Capture Therapy. (April 2022)

• Record Type: Journal Article
• Authors: Selva, A.; Bellan, L.; Bianchi, A.; Giustiniani, G.; Colautti, P.; Fagotti, E.; Pisent, A.; Conte, V.
• Is Part Of: Applied radiation and isotopes. Volume 182(2022)
• Publication Date: 2022-04
• Subjects: Thermal neutrons -- BNCT -- Microdosimetry; Radiology -- Periodicals; Radiation -- Industrial applications -- Periodicals; Nuclear chemistry -- Periodicals; Internet resource; Periodical; 660.298
• DOI: 10.1016/j.apradiso.2022.110144
• Languages: English
• ISSNs: 0969-8043

Abstract

Abstract: The MUNES project (MUltidisciplinary NEutron Source) aims at the realization of an intense accelerator-based source of thermal neutrons, suitable for Boron Neutron Capture Therapy (BNCT). This exploits the interaction of 5 MeV protons onto a beryllium target, producing a fast neutron spectrum, which is moderated to the thermal range by a large assembly made of a Polytetrafluoroethylene (PTFE) tank filled with heavy water, surrounded by graphite blocks. The thermal neutron field is extracted through a bismuth beam port. The microdosimetric characterization of this field was performed using a cylindrical avalanche-confinement Tissue Equivalent Proportional Counter (TEPC) equipped with interchangeable cathode walls, positioned in front of the beam port. Measurements were taken both with a boron-doped wall and with an undoped one. The comparison of the two microdosimetric distributions allows to distinguish the relative dose contribution due to alpha particles and lithium ions from the BNC reaction from that of photons and other particles from neutron interactions on the cathode walls. The Relative Biological Effectiveness (RBE) was also calculated from the convolution of the measured spectra with a biological weighting function. This paper describes the experimental microdosimetric approach and the results of measurements with a boron-loaded cathode performed for the first time at an accelerator-based BNCT source. Highlights: Microdosimetric spectra were taken at an accelerator-based neutron source for BNCT. Measurements were performed both with boron-doped and undoped detector walls. The dose fractions due to gamma, neutron and BNC processes were discriminated. RBE and RBE-weighted dose were calculated using a biological weighting function.