
Near-Infrared Diffuse Correlation Spectroscopy for Assessment of Tissue Blood Flow 205
that require tissue oxygen for treatment ecacy. For example,
PDT requires tissue oxygen because the process creates singlet
oxygen, which, in turn, kills tumor cells, and damages local
vasculature (Yu et al. 2005b). PDT is well known to be less
ecacious in patients with hypoxic tumors (Busch et al. 2000,
Leach et al. 2002). Factors that modulate tissue oxygen include
BF, blood oxygenation, and oxygen metabolism, i.e., factors
that these new measurement tools can probe. Furthermore,
cancer therapy can alter tumor hemodynamic/metabolic sta-
tus, wh ...