## 4 Discussion  
The electron disequilibrium and high-gradient dosing make the small electron beam dosimetry challenging. Diode detectors are considered suitable for measurements of the scanning data and the relative output factors in small electron beams [13]. The microfSilicon detector has been recently introduced to overcome the performance of its predecessor diode E because of its smaller sensitivity to temperature, higher dose stability and lower dose per pulse dependence [16]. In fact, the microfSilicon entrance window is more water equivalent, thanks to the reduction in density of the casting compound on top of the silicon chip, compared to the predecessor [11]. The lack of investigation of the microfSilicon detector performance in high-energy small electron beams boosted the need for the characterization of clinical electron beams shaped by commercial tubular applicators performed in this study. According to IAEA 398, plane-parallel air-filled ionization chambers are recommended to be used for PDD measurements at all electron energies and, below 10 MeV, their use is mandatory. However, the diameter of the collecting electrode should be considered when performing small beam dosimetry to avoid the influence of radial non-uniformities of the beam profile [14]. TG25 suggested that measurements can be done with an ionization chamber that is small enough such that its active volume fits in the flat portion of the beam [1,13]. Diode and diamond detectors can be used as an alternative to the ionization chamber after verifying that the detector is suitable for depth dose measurements trough test comparisons at a representative beam quality [14]. To this purpose, the Advanced Markus ionization chamber has been used as reference for PDD and OF measurements for the 50 mm diameter applicator, and the differences between each solid-state dosimeter and the ionization chamber were evaluated. Diode E detector presented the overall minimum difference in dose and distance with the ion chamber data, and silicon diode detectors have been considered suitable for electron dosimetry for a long time in the literature [1,13]. So far, the diode E was chosen as the reference detector for the remaining tubular collimators to compare measurements performed by the microfSilicon and the microDiamond. The dose difference, in % over the entire depth range, was evaluated for PDD. However, the dose difference may not be appropriate to compare the variability among detectors in the region between the R80 and the R20, where the dose gradient is higher. So, thedistance-to-agreement, representing the minimum distance to the same value from the reference data was calculated for the solid-state detectors. We found that differences between solid-state detectors are still consistent with the measurement uncertainty, taking into account the step size used for data acquisition and the absence of the reference detectors due to the small size of the investigated fields. The results reported in Table 1, regarding the maximum distance-to-agreement, averaged over all beam energies between the ion chamber and each solid-state dosimeter data, were found to be similar to the ones presented by [PERSON] et al. [12]. In particular, for the 50 mm tubular applicator, our results were 0.4 mm, 0.6 mm, and 0.5 mm for diode E, microDiamond, and microSilicon, respectively. Similarly, for the same solid-state detectors, [PERSON] et al. [12] obtained 0.51 mm, 0.68 mm, and 0.86 mm, respectively, in the 10 \(\times\) 10 cm\({}^{2}\) reference field size. A maximum deviation of 0.4 mm in penumbra evaluation was found in our measurements. In this study transverse beam profiles measurements were performed for each energy and beam aperture at zref, as derived for the reference field 10 \(\times\) 10 cm\({}^{2}\). Differently, [PERSON] et al. acquired beam profiles at the depth of maximum dose, as derived from PDD measurements for different detectors, and they found a maximum difference up to 1.1 mm in penumbra values for beam profiles measured at slightly different depths [4].