title: [Determination of the repair half-time of human nasopharyngeal carcinoma cell lines CNE1, CNE2, HONE1 and C666-1].
abstract: OBJECTIVE
  To determine the repair half-time (T1/2), a speed parameter of sub-lethal damage repair (SLDR), of human nasopharyngeal carcinoma (NPC) cell lines CNE1, HONE1, C666-1 and CNE2.
  
  
  METHODS
  A total radiation dose of 8 Gy divided into 4+4 Gy was delivered to the cell lines at the interval of 0 s, 15 s, 30 s, 1 h, 2 h, 4 h or 6 h. The cell survival fractions were determined using the standard cell clonogenic assay. The curves of the changes in the surviving cell fraction after a total dose of 8 Gy, as a function of the interval between the two doses of 4 Gy, were fitted manually, and the T1/2 of each cell line was calculated according to the curves.
  
  
  RESULTS
  The T1/2 of CNE1, HONE1, C666-1 and CNE2 were 18 s, 22 s, 29 s and 27 s, respectively.
  
  
  CONCLUSIONS
  The speed of SLDR of NPC cells is quite rapid, indicating that the fraction delivery time longer than 20 s might decrease the effect of radiotherapy.
authors.affiliation: Department of Radiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. 40809773@qq.com
authors.forename: Wen-jun
authors.initials: WJ
authors.lastname: Wang
authors.forename: Xiao-kang
authors.initials: XK
authors.lastname: Zheng
authors.forename: Jia-bin
authors.initials: JB
authors.lastname: Liu
authors.forename: Ya-wei
authors.initials: YW
authors.lastname: Yuan
authors.forename: Long-hua
authors.initials: LH
authors.lastname: Chen
authors.forename: Heng-wen
authors.initials: HW
authors.lastname: Sun
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D011832:Radiation Injuries / Q000517:prevention & control*; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated