Erratum: "Dynamically accumulated dose and 4D accumulated dose for moving tumors" [Med. Phys. 39(12), 7359–7367 (2012)]. Issue 4 (6th March 2013) - Li, Heng; Li, Yupeng; Zhang, Xiaodong; Li, Xiaoqiang; Liu, Wei; Gillin, Michael T.; Zhu, X. Ronald