## 4 Conclusions  
In this study, microdosimetric measurements were carried out using an avalanche-confinement tissue-equivalent proportional counter (TEPC), a specialized detector with interchangeable cathodes. Opting for this specific choice of TEPC provides the advantage that, aside from the boron content, all other characteristics of the detector remain exactly the same, allowing for a more controlled data processing. Propane was used to fill the gas cavity at a pressure that simulated a 1 \(\upmu\)m site size. The cathode walls were doped with varying concentrations of \({}^{10}\)B, ranging from 0 to 100 ppm. Pairwise measurements were performed, both with and without boron, to distinguish and isolate the gamma, neutron, and pure BNC components. We indirectly verified the nominal \({}^{10}\)B concentration, observing deviations from the nominal values of less than 3%. Additionally, we developed a robust procedure to extract the contribution of boron neutron capture (BNC) reactions for arbitrary \({}^{10}\)B concentrations. This experimental methodology allows for the use of microdosimetric measurements performed at an arbitrary boron concentration to predict the average effectiveness of boron uptake at any other concentration. With the exception of publications from our research group at LNL, only the works of [PERSON], [PERSON], and [PERSON] provide experimental results that can be directly compared with the measurements conducted in this study, but the direct comparison is limited with regard to the boron neutron capture (BNC) component. This limitation arises because the radiation fields were not the same, and components other than the BNC are strongly dependent on the radiation field composition and detector characteristics (e.g., wall thickness). The comparison with the BNC components measured by [PERSON], [PERSON], and [PERSON] is very good, with small discrepancies that are consistent with the different experimental conditions. Despite the limitations relative to the boron distribution within and around the biological target, which were mentioned in the discussion, the microdosimetric approach provides valuable insights into the biological effects of BNCT on cancerous and healthy tissues, contributing to the development of innovative treatment strategies. Potential applications of microdosimetry include, for instance, the implementation of experimental microdosimetric spectra, measured at different depths in phantom, as input data of advanced treatment planning [31; 32]. It is crucial to emphasize that the microdosimetric component of boron neutron capture (BNC), measured using the TEPC method, corresponds to the cellular effect when \({}^{10}\)B atoms are situated in the tissue surrounding the biological sensitive target, rather than within it. Since the BNC dose is released inside the cell by two ions emitted simultaneously at an angle of 180\({}^{\circ}\), the TEPC, by design, captures ionization events resulting from only one of the two ions produced in the A-150 walls. Consequently, the event size measured by the TEPC is generally smaller than the event size produced by a BNC reaction inside the biological target. To further explore the impact of different boron atom placements within biological tissue at micrometer scale, including a heterogeneous distribution, we recommend conducting Monte Carlo simulations. TEPC measurements can serve as a valuable tool to validate the Monte Carlo model. Conceptualization, V.C. ; methodology, V.C., A.B. and A.S.; data analysis, V.C. ; writing--original draft preparation, V.C. ; writing--review and editing, A.B. and A.S. All authors have read and agreed to the published version of the manuscript. **Funding:** This work was supported by the Fifth Scientific Commission of the Italian National Institute for Nuclear Physics (INFN). **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Raw data were generated at Legnaro National Laboratories of INFN.