title: Variation in the gross tumor volume and clinical target volume for preoperative radiotherapy of primary large high-grade soft tissue sarcoma of the extremity among RTOG sarcoma radiation oncologists.
abstract: OBJECTIVE
  To evaluate variability in the definition of preoperative radiotherapy gross tumor volume (GTV) and clinical target volume (CTV) delineated by sarcoma radiation oncologists.
  
  
  METHODS
  Extremity sarcoma planning CT images along with the corresponding diagnostic MRI from two patients were distributed to 10 Radiation Therapy Oncology Group sarcoma radiation oncologists with instructions to define GTV and CTV using standardized guidelines. The CT data with contours were then returned for central analysis. Contours representing statistically corrected 95% (V95) and 100% (V100) agreement were computed for each structure.
  
  
  RESULTS
  For the GTV, the minimum, maximum, mean (SD) volumes (mL) were 674, 798, 752±35 for the lower extremity case and 383, 543, 447±46 for the upper extremity case. The volume (cc) of the union, V95 and V100 were 882, 761, and 752 for the lower, and 587, 461, and 455 for the upper extremity, respectively. The overall GTV agreement was judged to be almost perfect in both lower and upper extremity cases (kappa=0.9 [p<0.0001] and kappa=0.86 [p<0.0001]). For the CTV, the minimum, maximum, mean (SD) volumes (mL) were 1145, 1911, 1605±211 for the lower extremity case and 637, 1246, 1006±180 for the upper extremity case. The volume (cc) of the union, V95, and V100 were 2094, 1609, and 1593 for the lower, and 1533, 1020, and 965 for the upper extremity cases, respectively. The overall CTV agreement was judged to be almost perfect in the lower extremity case (kappa=0.85 [p<0.0001]) but only substantial in the upper extremity case (kappa=0.77 [p<0.0001]).
  
  
  CONCLUSIONS
  Almost perfect agreement existed in the GTV of these two representative cases. There was no significant disagreement in the CTV of the lower extremity, but variation in the CTV of upper extremity was seen, perhaps related to the positional differences between the planning CT and the diagnostic MRI.
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI 53045, USA. dwang@mcw.edu
authors.forename: Dian
authors.initials: D
authors.lastname: Wang
authors.forename: Walter
authors.initials: W
authors.lastname: Bosch
authors.forename: David G
authors.initials: DG
authors.lastname: Kirsch
authors.forename: Rawan
authors.initials: R
authors.lastname: Al Lozi
authors.forename: Issam
authors.initials: I
authors.lastname: El Naqa
authors.forename: David
authors.initials: D
authors.lastname: Roberge
authors.forename: Steven E
authors.initials: SE
authors.lastname: Finkelstein
authors.forename: Ivy
authors.initials: I
authors.lastname: Petersen
authors.forename: Michael
authors.initials: M
authors.lastname: Haddock
authors.forename: Yen-Lin E
authors.initials: YL
authors.lastname: Chen
authors.forename: Naoyuki G
authors.initials: NG
authors.lastname: Saito
authors.forename: Ying J
authors.initials: YJ
authors.lastname: Hitchcock
authors.forename: Aaron H
authors.initials: AH
authors.lastname: Wolfson
authors.forename: Thomas F
authors.initials: TF
authors.lastname: DeLaney
mesh_terms: D000368:Aged; D001132:Arm; D032921:Consensus; D005121:Extremities / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D057234:Preoperative Period; D018787:Radiation Oncology; D015203:Reproducibility of Results; D012509:Sarcoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy; D012983:Soft Tissue Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy; D013848:Thigh; D014057:Tomography, X-Ray Computed / Q000379:methods; D047368:Tumor Burden