Abstract: Systems and methods for calibrating and controlling leaves of a multi-leaf collimator are disclosed. According to an exemplary method, a controller may receive images of collimator leaves and may determine a minor offset between an imaging marker and the tip of the respective leaf. In addition, the controller may quantify a barrel distortion effect associated with a leaf-imaging camera. The controller may correct leaf position data using the minor offsets and barrel distortion quantification, and may use the corrected leaf positions to accurately place the leaves during radiotherapy. Advantageously, a desired beam shaping window may be formed with the leaves, ensuring that healthy tissue is minimally irradiated while also ensuring that the target tissue receives the correct radiation dose. Embodiments of the present disclosure provide collimator calibration techniques which may be faster than prior calibration techniques, allowing shortened calibration times and faster radiotherapy sessions.