title: Inhomogeneity correction in radiotherapy for lung cancer in multicenter clinical trials.
abstract: OBJECTIVE
  Dose distribution in patients in past multicenter clinical trials was reviewed from the perspective of clinicians to evaluate the quality of treatment and to improve the quality of future clinical trials.
  
  
  METHODS
  Thirty patients with stage III lung cancer, who had undergone radical radiation therapy in multicenter clinical trials were retrospectively reviewed. A two-dimensional treatment planning system using Clarkson integration was used to calculate correction factors at the primary lesions and at the mediastinal lymph nodes.
  
  
  RESULTS
  Correction factors at the primary lesions ranged from 1.00 to 1.12 (mean, 1.06) and from 1.02 to 1.14 (mean, 1.06) in the AP/PA fields and in the oblique fields, respectively. The lowest values of correction factors at the mediastinal lymph nodes on the axial plane including the primary lesions ranged from 0.93 to 1.04 (mean, 0.98) and from 0.97 to 1.10 (mean, 1.02) in the AP/PA fields and in the oblique fields, respectively. In 14 patients whose primary tumor was located in the upper lung field, the correction factors at the subcarinal lymph nodes ranged from 0.90 to 1.01 (mean, 0.96) in the AP/PA fields.
  
  
  CONCLUSIONS
  Delivered doses lower than those prescribed at the mediastinal lymph nodes should be taken into consideration to improve the quality of multicenter clinical trials.
authors.affiliation: Department of Radiology, Osaka Prefectural Habikino Hospital, Japan.
authors.forename: Takuhito
authors.initials: T
authors.lastname: Tada
authors.forename: Kazuo
authors.initials: K
authors.lastname: Minakuchi
authors.forename: Hisashi
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Fukuda
authors.forename: Mineyoshi
authors.initials: M
authors.lastname: Bun
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Nakajima
mesh_terms: D002986:Clinical Trials as Topic; D006801:Humans; D008168:Lung / Q000528:radiation effects; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008198:Lymph Nodes / Q000528:radiation effects; D015337:Multicenter Studies as Topic; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D011882:Radiotherapy, High-Energy; D012189:Retrospective Studies