title: Feasibility of shrinking field radiation therapy through 18F-FDG PET/CT after 40 Gy for stage III non-small cell lung cancers.
abstract: OBJECTIVE
  To explore the feasibility of shrinking field technique after 40 Gy radiation through 18F-FDG PET/ CT during treatment for patients with stage III non-small cell lung cancer (NSCLC).
  
  
  METHODS
  In 66 consecutive patients with local-advanced NSCLC, 18F-FDG PET/CT scanning was performed prior to treatment and repeated after 40 Gy. Conventionally fractionated IMRT or CRT plans to a median total dose of 66 Gy (range, 60-78 Gy) were generated. The target volumes were delineated in composite images of CT and PET. Plan 1 was designed for 40 Gy to the initial planning target volume (PTV) with a subsequent 20-28 Gy-boost to the shrunken PTV. Plan 2 was delivering the same dose to the initial PTV without shrinking field. Accumulated doses of normal tissues were calculated using deformable image registration during the treatment course.
  
  
  RESULTS
  The median GTV and PTV reduction were 35% and 30% after 40 Gy treatment. Target volume reduction was correlated with chemotherapy and sex. In plan 2, delivering the same dose to the initial PTV could have only been achieved in 10 (15.2%) patients. Significant differences (p<0.05) were observed regarding doses to the lung, spinal cord, esophagus and heart.
  
  
  CONCLUSIONS
  Radiotherapy adaptive to tumor shrinkage determined by repeated 18F-FDG PET/CT after 40 Gy during treatment course might be feasible to spare more normal tissues, and has the potential to allow dose escalation and increased local control.
authors.affiliation: Department of Radiation Oncology, Shandong's Key Laboratory of Radition Oncology, Jinan, China.
authors.forename: Xiu-Ping
authors.initials: XP
authors.lastname: Ding
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Bao-Sheng
authors.initials: BS
authors.lastname: Li
authors.forename: Hong-Sheng
authors.initials: HS
authors.lastname: Li
authors.forename: Zhong-Tang
authors.initials: ZT
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Yi
authors.forename: Hong-Fu
authors.initials: HF
authors.lastname: Sun
authors.forename: Dong-Qing
authors.initials: DQ
authors.lastname: Wang
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D005240:Feasibility Studies; D005260:Female; D019788:Fluorodeoxyglucose F18; D005720:Gamma Rays; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011379:Prognosis; D019275:Radiopharmaceuticals; D011879:Radiotherapy Dosage / Q000592:standards*; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18