Scintillator-based radiation therapy quality assurance

Systems, methods, and computer software are disclosed for determining a shape of a radiation field generated by a radiation delivery system through the use of a scintillator and a camera that is configured to acquire images of light emitted by the scintillator during delivery of a radiation beam. A support structure may be mounted to the radiation delivery system and the scintillator and camera may be fixed to the support structure such that the scintillator is not perpendicular to the axis of the radiation beam. An edge detection algorithm may be applied to radiation patterns present in the camera images in order to determine the location of an edge of a leaf of a multi-leaf collimator.