In Figure 3C, by using immunohistochemistry (IHC) at 4 h post-irradiation, we showed that with a SOBP of 7 mm, we were able to deliver the dose to the upper tumor part, as indicated by the labeling for the apoptotic marker cleaved-caspase-3, while nearly no radiation dose was delivered to the deepest tumor part, as shown by the absence of caspase-3 labeling (Figure 3C,F). Here, CASP3 is linked to neoplasm.