title: Radiation-induced temporal lobe injury after intensity modulated radiotherapy in nasopharyngeal carcinoma patients: a dose-volume-outcome analysis.
abstract: BACKGROUND
  To identify the radiation volume effect and significant dosimetric parameters for temporal lobe injury (TLI) and determine the radiation dose tolerance of the temporal lobe (TL) in nasopharyngeal carcinoma (NPC) patients treated with intensity modulated radiation therapy (IMRT).
  
  
  METHODS
  Twenty NPC patients with magnetic resonance imaging (MRI)-diagnosed unilateral TLI were reviewed. Dose-volume data was retrospectively analyzed.
  
  
  RESULTS
  Paired samples t-tests showed all dosimetric parameters significantly correlated with TLI, except the TL volume (TLV) and V₇₅ (the TLV that received ≥75 Gy, P = 0.73 and 0.22, respectively). Receiver operating characteristic (ROC) curves showed V₁₀ and V₂₀ (P = 0.552 and 0.11, respectively) were the only non-significant predictors from V₁₀ to V₇₀ for TLI. D(0.5cc) (dose to 0.5 ml of the TLV) was an independent predictor for TLI (P < 0.001) in multivariate analysis; the area under the ROC curve for D(0.5cc) was 0.843 (P < 0.001), and the cutoff point 69 Gy was deemed as the radiation dose limit. The distribution of high dose 'hot spot' regions and the location of TLI were consistent.
  
  
  CONCLUSIONS
  A D0.5cc of 69 Gy may be the dose tolerance of the TL. The risk of TLI was highly dependent on high dose 'hot spots' in the TL; physicians should be cautious of such 'hot spots' in the TL during IMRT treatment plan optimization, review and approval.
authors: State Key Laboratory of Oncology in Southern China, Department of Radiation Oncology, Cancer Center, Sun Yat-sen University, Guangzhou 510060, People's Republic of China. majun2@mail.sysu.edu.cn.
authors: Ying
authors: Y
authors: Sun
authors: Guan-Qun
authors: GQ
authors: Zhou
authors: Zhen-Yu
authors: ZY
authors: Qi
authors: Li
authors: L
authors: Zhang
authors: Shao-Min
authors: SM
authors: Huang
authors: Li-Zhi
authors: LZ
authors: Liu
authors: Li
authors: L
authors: Li
authors: Ai-Hua
authors: AH
authors: Lin
authors: Jun
authors: J
authors: Ma
mesh_terms: D000328:Adult; D002277:Carcinoma; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000532:radiotherapy; D009367:Neoplasm Staging; D012372:ROC Curve; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000473:pathology*; D011836:Radiation Tolerance; D011874:Radiometry; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D013702:Temporal Lobe / Q000473:pathology* / Q000528:radiation effects*; D016896:Treatment Outcome; D055815:Young Adult
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