An x-ray beam generator includes an x-ray source and a collimation ring to generate a sweeping x-ray beam. The x-ray source emits a beam of x-ray radiation through an opening in an enclosure. The collimation ring defines one or more apertures, and encompasses the enclosure at the opening and has an outer diameter less than 150% of an outer diameter of the enclosure at the opening. A support bearing is coupled to the collimation ring and enables the collimation ring to rotate about the x-ray source. A drive system rotates the collimation ring about the x-ray source during activation of the x-ray source to form the sweeping x-ray beam via the one or more apertures.