Figure 3

In vitro study. PCA in the HW region of CTX-TNA2 (astrocytes, top) and F98 (glioma, bottom) irradiated with the indicated doses; for each cell line, the PCA scores (upper row) and loadings (lower row) are included. Explained variances by the PCs are about 85% for both cell lines. Each point of the PCA scores represents a cell spectrum, and colours correspond to the irradiation configuration: blue for control (non-irradiated), red for BB, green for MB\(_{\text{peak}}\) and orange for MB\(_{\text{valley}}\). Vertical lines in the loadings indicate the most relevant peaks for each PC: dashed and pink for PC-1, and dot-dashed and purple for PC-2. The mean doses for BB and pMBRT irradiations were 2, 5 and 10 Gy for astrocytes, and 5, 10 and 20 Gy for glioma cells. For pMBRT, the specific peak and valley doses were 6.5 ± 0.3 Gy and 0.70 ± 0.05 Gy (\({\overline{D}}\) = 2.1 ± 0.1 Gy), 15.2 ± 0.8 Gy and 1.6 ± 0.1 Gy (\({\overline{D}}\) = 5.2 ± 0.3 Gy), 32 ± 1 Gy and 3.0 ± 0.2 Gy (\({\overline{D}}\) = 10.0 ± 0.5 Gy), and 64 ± 3 Gy and 5.5 ± 0.3 Gy (\({\overline{D}}\) = 19.8 ± 0.9 Gy). MBs were generated by means of a divergent collimator of 15 slits with a width of 400 \(\upmu \)m, separated a c-t-c distance of 4 mm.