Li Liang, Niu Tianye, Cho Seungryong, Wang Zhentian
Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
Medical Physics Program, George W. Woodruff School, Georgia Institute of Technology, 770 State Street, Atlanta GA 30332-0745, USA.
Comput Math Methods Med. 2014;2014:765163. doi: 10.1155/2014/765163. Epub 2014 Jun 4.