Cherenkov Radiation Induced by Megavolt X-Ray Beams in the Second Near-Infrared Window

Although the Cherenkov light contains mostly short-wavelength components, it is beneficial in the aspect of imaging to visualize it in the second near-infrared (NIR-II) window. In this study, Cherenkov imaging was performed within the NIR-II range on megavolt X-ray beams delivered by a medical linear accelerator. A shielding system was used to reduce the noises of the NIR-II image, enabling high quality signal acquisition. It was demonstrated that the NIR-II Cherenkov imaging is potentially a tool for radiotherapy dosimetry, and correlates well with different parameters. The NIR-II Cherenkov imaging is less susceptible to scattering, while more susceptible to absorption, compared with the visible-near-infrared imaging. Finally, a mouse was used to demonstrate this technology on animals. These results indicate the potentials to apply NIR-II Cherenkov imaging in the practice of radiotherapy.