[2] [2] Kyriakou Y, Meyer E, Prell D, et al. Med. Phys., 2010, 37(7): 5179.

[4] [4] Tang Zhiwei, Hu Guangshu. Tsinghua Science and Technology, 2011, 16(4): 352.

[7] [7] Midgley S M. Physics Medicine and Biology, 2011, 56(10): 2943.

[8] [8] Xu Qiong, Yu Hengyong, Mou Xuanqin, et al. IEEE Transaction on Biomedical Engineering, 2012, 59(6): 1711.

[9] [9] Daniel J Lingenfelter, Fessler J A. IEEE Trans. Nuc. Sci., 2013, 60(1): 204.

[10] [10] Wang X, Meier D, Taguchi K, et al. Med. Phys., 2011, 38(3): 1534.

[11] [11] Shikhaliev P M, Fritz S G, Chapman J W. Med. Phys., 2009, 36(11): 5107.

[13] [13] Zhao Yunsong, Li Mengfei. PLOS ONE. 2015, 10(12): 1.