Abstract: A system and method for recording in real-time the duration, strength, and position of multiple collimated beams of ionizing radiation as delivered during stereotactic radiosurgery for the purpose calibrating the radiological system and verifying the treatment plans for various lesions. The beams of ionizing radiation are made visible by means of a cone or paraboloid shaped scintillator the interior of which is viewed by a sensitive visible-light camera equipped with fish-eye style optics mounted in a darkened enclosure. As the beam enters and exits the scintillator cone, two bright spots are seen in the camera's field of view. The centroids of these spots create a hodoscope and describe the path of the beam through three dimensional space. A computer connected to the camera measures the location and intensity of these spots over time during radiosurgery, calculates each beam path, and archives the spot parameters and computed beam paths to memory.