## 3 Results  
### Percentage Depth-Dose Curves and Beam Profiles Measurements  
Figure 1 shows the PDD curves measured for all beam energies with the three solid-state detectors and the plane-parallel ionization chamber for the 50 mm diameter field. The differences between PDDs measured by the solid-state dosimeters and the ionization chamber are also shown. An agreement of \(\pm\)3% was observed among the detector responses for all the beam energies over the whole PDD curve, except for the region close to the water surface, where the detectors are partially in air. The difference, grown to about 5% in the maximum dose gradient area, is only for the 12 MeV energy beam. The maximum difference in distance (mm) within the 20-80% region, reported in Table 1, for each solid-state detector relative to the reference data, was 0.7 mm for all beam energies, except for 12 MeV, where 1.3 mm is the maximum distance. As far as concerned only the diode E, the maximum difference in distance was 0.4 mm in all curves. No statistically significant differences were found between the reference data and those measured by the other detectors. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Difference in Distance (mm)**} & \multicolumn{4}{c}{**50 mm**} \\  & \multicolumn{2}{c}{**20 mm**} & \multicolumn{4}{c}{**30 mm**} & \multicolumn{4}{c}{**40 mm**} & \multicolumn{4}{c}{**50 mm**} \\
**Energy** & **m-D** & **m-Si** & **m-D** & **m-Si** & **m-D** & **m-Si** & **d-E** & **m-D** & **m-Si** \\
**(MeV)** & & & & & & & & & \\ \hline
4 & 0.3 & 0.4 & 0.2 & 0.1 & 0.3 & 0.4 & 0.3 & 0.03 & 0.1 \\
6 & 0.2 & 0.1 & 0.3 & 0.1 & 0.4 & 0.1 & 0.4 & 0.4 & 0.3 \\
9 & 0.4 & 0.9 & 0.4 & 0.4 & 0.5 & 0.7 & 0.4 & 0.7 & 0.6 \\
12 & 0.5 & 0.8 & 1.1 & 0.4 & 1.1 & 0.6 & 0.3 & 1.3 & 0.9 \\ mean & 0.4 & 0.6 & 0.5 & 0.3 & 0.6 & 0.5 & 0.4 & 0.6 & 0.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Maximum difference in distance (mm), within the 20-80% PDD region for the solid-state detectors (diode E reported as d-E, microDiamond as m-D and microSilicon as m-Si), with respect to the chosen reference for each beam energy. The mean value over all beam energies was also shown. Figure 1: In the upper part: PDD curves measured with the three solid-state detectors and the plane-parallel ionization chamber for the 50 mm diameter field; the percentage doses are relative to the peak of the PDD curve. In the bottom part: % differences between PDDs, measured by the solid-state dosimeters and the ionization chamber. For the remaining tubular collimators, the maximum difference over the entire depth range was within 4%, and the maximum difference in distance within the region of the curve maximum slope was 1.1 mm for all beam energies. Similar results were obtained for the microDiamond and microSilicon detectors. The PDD curves, measured by the three solid-state detectors in the 20 mm diameter field for all beam energies, are reported in Figure 2, together with the respective percentage differences between PDDs, measured by the microDiamond, the microSilicon dosimeters, and the diode E data. Table 2 summarizes the most relevant dosimetric parameters extracted from PDD curves for the 50 mm diameter field, showing a maximum deviation of about 1 mm for all the investigated depth parameters and 0.3 MeV for E\({}_{0}\), measured by the solid-state detectors, with respect to the plane-parallel ionization chamber. The dosimetric characteristics of all applicators, except for the maximum diameter field, and all beam energies are reported in Table 3: a maximum deviation of 1.6 mm on R100, of 0.8 mm for all the other depth parameters investigated, and 0.2 MeV for E\({}_{0}\) were found between microDiamond and microSilicon measurements and the diode E data. The electron beam parameters R100, R80, and R50 shifted toward the phantom surface with decreasing field dimensions, particularly for the smallest field size. Furthermore, these parameters increased with increasing energy, as electrons penetrated deeper into the phantom.