title: Spect-guidance to reduce radioactive dose to functioning lung for stage III non-small cell lung cancer.
abstract: OBJECTIVE
  To investigate the treatment effect of additional information obtained by single photon emission computed tomography (SPECT) lung perfusion imaging (LPI) in the radiotherapy planning process for patients with stage III non-small cell lung cancer (NSCLC).
  
  
  METHODS
  39 patients with stage III NSCLC were enrolled. Gross tumor volume (GTV) was outlined by SPECT/CT images, SPECT-LPIs being used to define functional lung (FL) and non-functional lung (NFL) regions. Two sets of IMRT plans were designed to deliver 64Gy to PTV. One was a regular IMRT plan using CT images only (Plan 1), and the other was a corresponding IMRT plan using co-registered images (Plan 2). FLVx (the % volume of functional lung receiving ≥x Gy) and WLVx (% volume of whole lung to receive ≥x Gy) were compared by paired Student's t test. Kendalls correlation was used to analyze the factor (s) related with the FLV20 decrease.
  
  
  RESULTS
  Compared with plan 1, both WLVx and FLVx were decreased in plan 2. WLV10, WLV15, WLV20, WLV25, WLV30 and WLV35 decreased 9.7%, 13.8%, 17.2%, 12.9%, 9.8% and 9.8%, and FLV10, FLV15, FLV20, FLV25, FLV30 and FLV35 decreased 10.8%, 14.6%, 17.3%, 14.5%, 14.5% and 10.5%. FLVx decreased significantly compared with WLVx. There were significant differences in WLV10, WLV15, WLV20, WLV25, WLV3 and FLV10, FLV15, FLV20, FLV25, FLV30 between plan 1 and plan 2 (P=0.002, 0.000, 0.000, 0.005, 0.027 and 0.002, 0.000, 0.000, 0.006, 0.010). According to Kendall correlation analysis, NFL had a negative relation with the percentage FLV20 decrease (r=-0.559, P<0.01), while the distance of PTV and NFL center had a significantly positive relation with the percentage of FLV20 decrease (r=0.768, P<0.01).
  
  
  CONCLUSIONS
  Routine use of SPECT-LPI for patients undergoing radiotherapy planning for stage III NSCLC appears warranted.
authors.affiliation: Sixth Department of Radiation Oncology, Shandong Cancer Hospital, Jinan, China.
authors.forename: Zhong-Tang
authors.initials: ZT
authors.lastname: Wang
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Wei
authors.forename: Xiu-Ping
authors.initials: XP
authors.lastname: Ding
authors.forename: Ming-Ping
authors.initials: MP
authors.lastname: Sun
authors.forename: Hong-Fu
authors.initials: HF
authors.lastname: Sun
authors.forename: Bao-Sheng
authors.initials: BS
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed