Solid tumors often exhibit abnormal morphology which can be characterized by increased permeability and low perfusion. The resulting tumor hypoxia has been correlated with poor prognosis, which may be due to ineffective therapy or survival of more aggressive phenotypes. External beam radiation therapy (EBRT) is often used to treat such tumors, where radiation dose is delivered on a daily fractionated basis over the course of weeks. A non-contact optical method for measuring in vivo oxygen levels during EBRT treatments has been developed to provide early indications of hypoxic tumor environments. This method uses a time-gated intensified imaging device to measure both Cherenkov emissions, which are generated in tissue by high energy electrons traveling faster than the phase-velocity of the medium, and Cherenkov-excited luminescence generated by the oxygen-sensitive phosphorescent compound, PtG4. Murine models have shown the ability to discriminate phosphorescence lifetime changes before and after animal sacrifice. Pixel-maps of the estimated pO2 can be generated from this data to show high spatial variability within a region of interest. By further camera optimization, this method can be expanded to show pO2 distributions for other physiological conditions in near real-time. Our imaging method has the unique ability to be integrated within existing clinical applications while providing a wide-field mapping of oxygen saturation, which is currently unavailable with existing point probes.

Date Published: 4 March 2019
PDF
Proc. SPIE 10862, Molecular-Guided Surgery: Molecules, Devices, and Applications V, 108621E (4 March 2019); doi: 10.1117/12.2511292

Published in SPIE Proceedings Vol. 10862:
Molecular-Guided Surgery: Molecules, Devices, and Applications V
Brian W. Pogue; Sylvain Gioux, Editor(s)