title: Functional dosimetric metrics for predicting radiation-induced lung injury in non-small cell lung cancer patients treated with chemoradiotherapy.
abstract: BACKGROUND
  Radiation-induced lung injury (RILI) is an important dose-limiting toxicity during thoracic radiotherapy. The purpose of this study is to investigate single photon emission computed tomography (SPECT) perfusion-weighted functional dose-volume histogram (FDVH) for predicting RILI in non-small cell lung cancer (NSCLC) patients treated with definitive chemoradiotherapy.
  
  
  METHODS
  Fifty-seven locally advanced NSCLC patients receiving chemoradiotherapy were enrolled prospectively. Patients had treatment scans and dose calculations to provide a standard dose-volume histogram (DVH). Fusion of SPECT and computed tomography scans provided perfusion-weighted FDVH and associated functional dosimetric parameters (relative volumes of functional lung receiving more than a threshold dose of 5 - 60 Gy at increments of 5 Gy [FV5 - FV60]). The predictive abilities of FDVH and DVH were calculated and compared based on the area under receiver operating characteristic (ROC) curve (AUC).
  
  
  RESULTS
  The accumulative incidence of  ≥  2 grade RILI was 19.3% with a median follow-up of 12 months. Univariate analysis showed that the functional (FV5 - FV60) and standard (V5 - V40) parameters were associated with RILI (all value of p < 0.05). Close correlations between a variety of functional and standard parameters were found. By ROC curve analysis, functional metrics (AUCs were 0.784 - 0.869) provided similarly (p value 0.233 - 1.000) predictive outcome to standard metrics (AUCs were 0.695 - 0.902) in lower - median dose level parameters (FV5 - FV40). However, FDVH seemed to add some predictive value in higher dose level, the best statistical significance for comparing FV60 with V60 was 0.693 vs. 0.511 (p = 0.055).
  
  
  CONCLUSIONS
  Functional metrics are identified as reliable predictors for RILI, however, this observation still needs to be further verified using a larger sample size.
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan, People’s Republic China.
authors.forename: Dongqing
authors.initials: D
authors.lastname: Wang
authors.forename: Jinbo
authors.initials: J
authors.lastname: Sun
authors.forename: Jingyu
authors.initials: J
authors.lastname: Zhu
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Li
authors.forename: Yanbo
authors.initials: Y
authors.lastname: Zhen
authors.forename: Songtao
authors.initials: S
authors.lastname: Sui
mesh_terms: D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000628:therapy*; D059248:Chemoradiotherapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D012372:ROC Curve; D011829:Radiation Dosage; D017564:Radiation Pneumonitis / Q000209:etiology*; D011874:Radiometry / Q000379:methods*; D015899:Tomography, Emission-Computed, Single-Photon