Six Michigan health systems have announced the creation of a joint venture to offer an emerging and costly type of cancer radiation therapy. The health systems are Ascension Health of Grand Blanc, the Barbara Ann Karmanos Cancer Center in Detroit, Henry Ford Health in Detroit, McLaren Health Care in Flint, Trinity Health in Novi, and the University of Michigan in Ann Arbor. Each system has agreed to contributed at least $13 million to the project, and they face a Sept. 6 deadline from the state's Certificate of Need Commission to develop a business plan for the facility. Proponents say the joint venture could create a model of cooperation among hospitals that have competed fiercely to promote new technology purchases.