Methods for optimal breast reconstruction are disclosed. The methods include steps for performing a mastectomy that preserves a breast skin envelope. A prosthesis may be inserted into the breast and may be inflated to preserve the shape of the breast skin envelope. The prosthesis may include, a base, a balloon coupled to the base, where the balloon may be inflated to preserve the shape of the breast skin envelope. The prosthesis may also include tube coupled to port for filling the balloon to a predetermined volume. A needle-lock system, coupled to the port may be used to inject, for example, fluids into the balloon. If a patient requires post-mastectomy radiation, breast reconstruction may be delayed and the prosthesis may remain in the breast cavity during the treatment. The treatment may be external beam radiation. Alternatively, the treatment may include brachytherapy technique for treating the internal breast cavity.