[5] Sidky Emil Y, Yu Lifeng, Pan Xiaochuan, et al. Journal of Applied Physics, 2005, 97(12): 124701.
[6] Zhang Li, Zhang Guowei, Chen Zhiqiang, et al. IEEE Nuclear Science Symposium Conference, 2007. 3089.
[7] Duan Xinhui, Wang Jia, Yu Lifeng, et al. Medical Physics, 2011, 38(2): 993.
[8] Du Yonghua, Wang Yanfei, Hua Wei. Nuclear Instruments and Methods in Physics Research, 2006, A565: 855.