Figure 7.

Physics of ionizing radiation interacting in scintillator-containing tissue. Electrons or positrons are emitted into tissue via (a) beta-emitting radionuclides or (b) as recoil or photoelectrons from the interactions of high-energy photons with tissue. Electrons or positrons passing through tissue generate reactive species through water radiolysis (e). Photons can directly interact in the nanoscintillator, generating electrons through Compton or photoelectric absorption (c). Electrons generated in tissue (a,b) or nanoscintillator (c) deposit a small fraction of their energy in nanoscintillators, producing scintillation photons (d). Scintillation photons absorbed by the photosensitizer (f) can generate singlet oxygen or other reactive oxygen species (g). The range of ionizing particles is several orders of magnitude larger than the diameter of nanoscintillators.