title: 18F-fluorodeoxyglucose positron emission tomography/computed tomography-based radiotherapy target volume definition in non-small-cell lung cancer: delineation by radiation oncologists vs. joint outlining with a PET radiologist?
abstract: OBJECTIVE
  (18)F-Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) has benefits in target volume (TV) definition in radiotherapy treatment planning (RTP) for non-small-cell lung cancer (NSCLC); however, an optimal protocol for TV delineation has not been determined. We investigate volumetric and positional variation in gross tumor volume (GTV) delineation using a planning PET/CT among three radiation oncologists and a PET radiologist.
  
  
  METHODS
  RTP PET/CT scans were performed on 28 NSCLC patients (Stage IA-IIIB) of which 14 patients received prior induction chemotherapy. Three radiation oncologists and one PET radiologist working with a fourth radiation oncologist independently delineated the GTV on CT alone (GTV(CT)) and on fused PET/CT images (GTV(PETCT)). The mean percentage volume change (PVC) between GTV(CT) and GTV(PETCT) for the radiation oncologists and the PVC between GTV(CT) and GTV(PETCT) for the PET radiologist were compared using the Wilcoxon signed-rank test. Concordance index (CI) was used to assess both positional and volume change between GTV(CT) and GTV(PETCT) in a single measurement.
  
  
  RESULTS
  For all patients, a significant difference in PVC from GTV(CT) to GTV(PETCT) exists between the radiation oncologist (median, 5.9%), and the PET radiologist (median, -0.4%, p = 0.001). However, no significant difference in median concordance index (comparing GTV(CT) and GTV(FUSED) for individual cases) was observed (PET radiologist = 0.73; radiation oncologists = 0.66; p = 0.088).
  
  
  CONCLUSIONS
  Percentage volume changes from GTV(CT) to GTV(PETCT) were lower for the PET radiologist than for the radiation oncologists, suggesting a lower impact of PET/CT in TV delineation for the PET radiologist than for the oncologists. Guidelines are needed to standardize the use of PET/CT for TV delineation in RTP.
authors.affiliation: Centre for Cancer Research and Cell Biology, Queen's University of Belfast, Belfast, N. Ireland, UK. Gerry.Hanna@googlemail.com
authors.forename: Gerard G
authors.initials: GG
authors.lastname: Hanna
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Carson
authors.forename: Tom
authors.initials: T
authors.lastname: Lynch
authors.forename: Jonathan
authors.initials: J
authors.lastname: McAleese
authors.forename: Vivian P
authors.initials: VP
authors.lastname: Cosgrove
authors.forename: Ruth L
authors.initials: RL
authors.lastname: Eakin
authors.forename: David P
authors.initials: DP
authors.lastname: Stewart
authors.forename: Ashraf
authors.initials: A
authors.lastname: Zatari
authors.forename: Joe M
authors.initials: JM
authors.lastname: O'Sullivan
authors.forename: Alan R
authors.initials: AR
authors.lastname: Hounsell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods; D018787:Radiation Oncology; D019275:Radiopharmaceuticals; D012074:Remission Induction; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods; D047368:Tumor Burden
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18