A system for monitoring radiation treatment images Cherenkov emissions from tissue of a subject. A processor of the system determines densities of a surface layer of the subject from 3D images of the tissue to determine correction factors. The processor uses these factors to correct the Cherenkov images for attenuation of Cherenkov light by tissue, making them proportional to radiation dose. In embodiments, the system obtains reflectance images of the subject, determines second correction factors therefrom, and applies the second correction factors to the Cherenkov emissions images. In embodiments, the corrected images of Cherenkov emissions are compared to dose maps of a treatment plan. A method of correcting Cherenkov emissions images includes determining tissue characteristics from CT or MRI images in a surface volume where Cherenkov is expected, using; imaging Cherenkov emissions; and using the tissue characteristics to correct the images for variations in Cherenkov light propagation through the tissue.