title: Early CT findings of tomotherapy-induced radiation pneumonitis after treatment of lung malignancy.
abstract: OBJECTIVE
  The objective of our study was to evaluate the early CT findings of tomotherapy-induced radiation pneumonitis.
  
  
  METHODS
  Tomotherapy was performed during the study period in 31 patients with peripheral pulmonary malignancies, 25 of whom underwent follow-up CT within the first 3 months after tomotherapy. These 25 patients, with a total of 77 target lesions, were enrolled for the analysis. We evaluated pulmonary toxicity by the Common Toxicity Criteria for Adverse Events (CTCAE) method and retrospectively analyzed the CT findings of radiation pneumonitis, focusing on the appearance (attenuation, shape, degree of fibrosis) and location (concentric vs eccentric, centrifugal vs centripetal) of radiation pneumonitis relative to the target lesions.
  
  
  RESULTS
  Radiation pneumonitis developed around 34 target lesions (34/77, 44%) in 13 patients (13/25, 52%) during the first 3 months after tomotherapy. Five patients needed steroid therapy (CTCAE grade 2, 5/25 [20%]) and the remaining eight patients required no additional treatment (CTCAE grade 0 or 1, 20/25 [80%]). In appearance, the common CT findings were irregular shape (18/34), ground-glass attenuation (19/34), and no or minimal fibrosis (33/34). The location of the radiation pneumonitis was eccentric (22/34) and centrifugal (19/34) relative to the target lesions.
  
  
  CONCLUSIONS
  Radiation pneumonitis commonly developed with minimal clinical findings within 3 months after tomotherapy. The CT findings were nonspecific: focal, irregular-shaped ground-glass opacities with minimal fibrosis. However, the location of the radiation pneumonitis tended not to correspond to the planned target volume and had a centrifugal distribution. In addition, the immediate area around the target tended to be spared.
authors.affiliation: Department of Radiology, St. Vincent's Hospital, The Catholic University of Korea, 665, Bupyeong-dong Bunpyeong-gu, Incheon 403-720, South Korea.
authors.forename: Hyun Jin
authors.initials: HJ
authors.lastname: Park
authors.forename: Ki Jun
authors.initials: KJ
authors.lastname: Kim
authors.forename: Seog Hee
authors.initials: SH
authors.lastname: Park
authors.forename: Chul-Seung
authors.initials: CS
authors.lastname: Kay
authors.forename: Jung Suk
authors.initials: JS
authors.lastname: Oh
mesh_terms: D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D017564:Radiation Pneumonitis / Q000000981:diagnostic imaging*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed / Q000379:methods*