A radiation treatment bra and method for its use are disclosed. In the illustrative embodiment, the bra includes adjustable elements (110,112,114) and a medial window (108). During radiation treatment planning, the elements (110,112,114) are adjusted to establish a reference breast geometry. The reference breast geometry is reproduced prior to an actual treatment session by repeating the original adjustment of the elements, as necessary. The medial window (108) enables a light field to be projected onto the patients chest, and read therefrom, thereby establishing proper alignment of the patient to the radiation treatment machine.
