title: CT ventilation functional image-based IMRT treatment plans are comparable to SPECT ventilation functional image-based plans.
abstract: OBJECTIVE
  To investigate the hypothesis that CT ventilation functional image-based IMRT plans designed to avoid irradiating highly-functional lung regions are comparable to single-photon emission CT (SPECT) ventilation functional image-based plans.
  
  
  METHODS
  Three IMRT plans were created for eight thoracic cancer patients using: (1) CT ventilation functional images, (2) SPECT ventilation functional images, and (3) anatomic images (no functional images). CT ventilation images were created by deformable image registration of 4D-CT image data sets and quantitative analysis. The resulting plans were analyzed for the relationship between the deviations of CT-functional plan metrics from anatomic plan metrics (ΔCT-anatomic) and those of SPECT-functional plans (ΔSPECT-anatomic), and moreover for agreements of various metrics between the CT-functional and SPECT-functional plans.
  
  
  RESULTS
  The relationship between ΔCT-anatomic and ΔSPECT-anatomic was strong (e.g., R=0.94; linear regression slope 0.71). The average differences and 95% limits of agreement between the CT-functional and SPECT-functional plan metrics (except for monitor units) for various structures were mostly less than 1% and 2%, respectively.
  
  
  CONCLUSIONS
  This study demonstrated a reasonable agreement between the CT ventilation functional image-based IMRT plans and SPECT-functional plans, suggesting the potential for CT ventilation imaging to serve as a surrogate for SPECT ventilation in functional image-guided radiotherapy.
authors.affiliation: Department of Radiation Oncology, University of California Davis, Sacramento, USA; Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kida
authors.affiliation: Philips Healthcare, Best, Netherlands.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Bal
authors.affiliation: Department of Digital Imaging, Philips Research, Hamburg, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Kabus
authors.affiliation: Department of Radiation Oncology, Stanford University, Stanford, USA.
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Negahdar
authors.affiliation: Department of Radiation Oncology, Stanford University, Stanford, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Shan
authors.affiliation: Department of Radiation Oncology, Stanford University, Stanford, USA.
authors.forename: Billy W
authors.initials: BW
authors.lastname: Loo
authors.affiliation: Radiation Physics Laboratory, Sydney Medical School, University of Sydney, Australia.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Keall
authors.affiliation: Department of Radiation Oncology, University of California Davis, Sacramento, USA. Electronic address: toyamamoto@ucdavis.edu.
authors.forename: Tokihiro
authors.initials: T
authors.lastname: Yamamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D005260:Female; D056973:Four-Dimensional Computed Tomography / Q000379:methods; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061089:Radiotherapy, Image-Guided; D012119:Respiration; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
keywords: 4D-CT; Deformable image registration; Lung cancer; Lung functional imaging; Radiation pneumonitis