title: Exceptionally high incidence of symptomatic grade 2-5 radiation pneumonitis after stereotactic radiation therapy for lung tumors.
abstract: BACKGROUND
  To determine the usefulness of dose volume histogram (DVH) factors for predicting the occurrence of radiation pneumonitis (RP) after application of stereotactic radiation therapy (SRT) for lung tumors, DVH factors were measured before irradiation.
  
  
  METHODS
  From May 2004 to April 2006, 25 patients were treated with SRT at the University of Tokyo Hospital. Eighteen patients had primary lung cancer and seven had metastatic lung cancer. SRT was given in 6-7 fields with an isocenter dose of 48 Gy in four fractions over 5-8 days by linear accelerator.
  
  
  RESULTS
  Seven of the 25 patients suffered from RP of symptomatic grade 2-5 according to the NCI-CTC version 3.0. The overall incidence rate of RP grade2 or more was 29% at 18 months after completing SRT and three patients died from RP. RP occurred at significantly increased frequencies in patients with higher conformity index (CI) (p = 0.0394). Mean lung dose (MLD) showed a significant correlation with V5-V20 (irradiated lung volume) (p < 0.001) but showed no correlation with CI. RP did not statistically correlate with MLD. MLD had the strongest correlation with V5.
  
  
  CONCLUSIONS
  Even in SRT, when large volumes of lung parenchyma are irradiated to such high doses as the minimum dose within planning target volume, the incidence of lung toxicity can become high.
authors.affiliation: Department of Radiology, University of Tokyo Hospital, Japan. yamachan07291973@yahoo.co.jp
authors.forename: Hideomi
authors.initials: H
authors.lastname: Yamashita
authors.forename: Keiichi
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Naoki
authors.initials: N
authors.lastname: Nakamura
authors.forename: Hiroki
authors.initials: H
authors.lastname: Koyanagi
authors.forename: Masao
authors.initials: M
authors.lastname: Tago
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Igaki
authors.forename: Kenshiro
authors.initials: K
authors.lastname: Shiraishi
authors.forename: Nakashi
authors.initials: N
authors.lastname: Sasano
authors.forename: Kuni
authors.initials: K
authors.lastname: Ohtomo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000150:complications* / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D010315:Particle Accelerators; D017564:Radiation Pneumonitis / Q000453:epidemiology* / Q000209:etiology*; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome