A radiation therapy apparatus includes a housing, a radiation source carried by the housing, and at least one aperture assembly carried by the housing. The aperture assembly includes a radiation aperture body having a shaped opening therein to control a radiation dosing profile, and an aperture holder with an aperture-receiving passageway therein receiving the radiation aperture body, and having a recessed end. A cover is received within the recessed end of the aperture holder and retains the radiation aperture body within the aperture holder. The cover has an opening aligned with the shaped opening in the radiation aperture body. The radiation aperture body, the aperture receiving passageway of the aperture holder and the opening of the cover have angled interfaces therebetween. A radiation filter is carried by the housing.
