Abstract: Provided herein is technology relating to medical imaging and radiation therapy and particularly, but not exclusively, to devices, methods, and systems for positioning a patient with respect to a radiation source to image the patient and/or to treat the patient by exposing the patient to a radiation beam produced by the radiation source.

Abstract: A computer-implemented method for calibrating a multi-leaf collimator of a radiotherapy device. The multi-leaf collimator comprises a plurality of leaves, each leaf comprising an imaging marker, wherein the radiotherapy device includes an imaging device configured to image the leaves. The method comprises: receiving, from the imaging device, an image of the multi-leaf collimator in a calibration position, wherein in the calibration position the tips of the leaves abut an edge of a rigid calibration block, the edge having a known calibration profile; calculating for each leaf, from the calibration profile and the location of the marker in the image, a minor offset of the marker relative to a reference point; and outputting calibration values based on the calculated minor offsets, wherein at least one leaf of the multi-leaf collimator is controlled based on the calibration values.

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.