[1] Yale Univ, Sch Med, Dept Radiol, POB 208042,Tompkins East 2, New Haven, CT 06520 USA
[2] Univ Washington, Sch Med, Dept Radiol, Seattle, WA 98195 USA
[3] Univ Washington, Sch Publ Hlth, Dept Hlth Serv, Seattle, WA 98195 USA
[4] Fred Hutchinson Canc Res Ctr, Hutchinson Inst Canc Outcomes Res, 1124 Columbia St, Seattle, WA 98104 USA
[5] Yale Univ, Sch Management, Sch Publ Hlth, New Haven, CT USA
[6] Yale Coll, Dept Econ, New Haven, CT USA