Our group is developing new techniques to localize tumors during radiation therapy using beam’s-eye-view (BEV) imaging. The BEV images show the internal anatomy that is being treated, while it is being treated. By using the treatment beam itself, we essentially get the information for free; no additional radiation is delivered to the patient and tumor localization is verified while the treatment beam is on. We have already used this system for treatment monitoring, verification, delivered dose calculation and adaptation. We have successfully demonstrated dynamic motion of the treatment beam aperture to precisely target the tumor. Current projects include an Academic-Industrial Partnership with Varian Medical Systems, Inc. (R01 CA188446) to design, build and test novel flat-panel imagers.