Multi-Leaf Collimator

Abstract

A multi-leaf collimator comprises an elongate leaf moveable in a longitudinal direction, and having an associated toothed rack driven by a pinion, wherein the rack is carried on an elongate actuator section, having a transversely extending link section, the leaf being connected to the link section and thereby being spaced from the actuator section. The pinion can thus be mounted on a shaft which is disposed transversely to the leaves of the array, and which passes between those leaves and their respective actuators. Some leaves can be driven via pinions mounted on shafts passing over the array, and other leaves can be driven via pinions mounted on shafts passing within the gaps between leaves and actuators. This means that twice the number of drive shafts can be fitted into the same length of array, thus either shortening the array or permitting more leaves and hence greater resolution. The drive mechanism can also be made as a separate unit. A separate drive unit is advantageous in manufacturing as it allows the drive unit to be produced, built and tested as a separate assembly in a specialist environment. Service replacement of the entire gearbox in the event of a fault will also be swifter, with minimal re-setting. Further, the gearbox will be an enclosed unit, with integral lubrication and shielded from environmental dust and debris. The invention also offers a major advantage in the leaf length is no longer dictated by the length of the rack. The leaf can be made smaller, saving material and reducing its weight. That reduction in weight will make movement of the leaf easier, improving both accuracy and reliability.

Dependencies are inferred from the claim text.