A method for assembling a secondary collimator including a first face plate having a first surface and an opposing second surface is provided. The method includes positioning a lamella assembly on the first face plate, wherein the lamella assembly includes at least one radiation-absorbing material layer and at least one radiation-transmitting material layer, such that a first surface of the lamella assembly is adjacent the second surface of the first face plate. The method also includes coupling a second face plate to the first face plate and the lamella assembly such that a first surface of the second face plate is adjacent a second surface of the lamella assembly.