Xenogen IVIS Spectrum is an in vivo optical system that uses both bioluminescent and fluorescent imaging to "light up" biological processes, including tumor detection. The systems gives researchers more imaging options and opens up the possibility of using this kind of optical imaging in humans — fluorescent imaging is approved for human use, bioluminescent imaging is not. Spectrum provides visualization, tracking and understanding of biological processes in living animals, in real time, at a molecular level.