A system may include emission of megavoltage radiation from a megavoltage radiation source, acquisition of a first image using an imaging device while first megavoltage radiation is emitted from the megavoltage radiation source and while a plurality of elements is between the megavoltage radiation source and the imaging device, and determination of an amount of scatter radiation based at least on areas of the acquired image corresponding to the plurality of elements. In some aspects, at least one of the plurality of elements is substantially pointed toward a focal spot of the megavoltage radiation source.