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Variability of Target Volume Delineation in Cervical Esophageal Cancer
International Journal of Radiation Oncology, Biology, Physics (1998)
  • Patricia Tai
  • Jake Van Dyk, University of Western Ontario
  • Edward Yu, University of Western Ontario
  • Jerry Battista, University of Western Ontario
  • Larry Stitt, University of Western Ontario
  • Terry Coad
PURPOSE: Three-dimensional (3D) conformal radiation therapy (CRT) assumes and requires the precise delineation of the target volume. To assess the consistency of target volume delineation by radiation oncologists, who treat esophageal cancers, we have performed a transCanada survey. MATERIALS AND METHODS: One of three case presentations, including CT scan images, of different stages of cervical esophageal cancer was randomly chosen and sent by mail. Respondents were asked to fill in questionnaires regarding treatment techniques and to outline boost target volumes for the primary tumor on CT scans, using ICRU-50 definitions. RESULTS: Of 58 radiation oncologists who agreed to participate, 48 (83%) responded. The external beam techniques used were mostly anterior-posterior fields, followed by a multifield boost technique. Brachytherapy was employed by 21% of the oncologists, and concurrent chemotherapy by 88%. For a given case, and the three volumes defined by ICRU-50 (i.e., gross tumor volume [GTV], clinical target volume [CTV], and planning target volume [PTV]) we determined: 1. The total length in the cranio-caudal dimension; 2. the mean diameter in the transverse slice that was located in a CT slice that was common to all participants; 3. the total volume for each ICRU volume; and 4. the (5, 95) percentiles for each parameter. The PTV showed a mean length of 14.4 (9.6, 18.0) cm for Case A, 9.4 (5.0, 15.0) cm for Case B, 11.8 (6.0, 16.0) cm for Case C, a mean diameter of 6.4 (5.0, 9.4) cm for Case A, 4.4 (0.0, 7.3) cm for Case B, 5.2 (3.9, 7.3) cm for Case C, and a mean volume of 320 (167, 840) cm3 for Case A and 176 (60, 362) cm3 for Case C. The results indicate variability factors (95 percentile divided by 5 percentile values) in target diameters of 1.5 to 2.6, and in target lengths of 1.9 to 5.0. CONCLUSION: There was a substantial inconsistency in defining the planning target volume, both transversely and longitudinally, among radiation oncologists. The potential benefits of 3D treatment planning with high-precision dose delivery could be offset by this inconsistency in target-volume delineation by radiation oncologists. This may be particularly important for multicenter clinical trials, for which quality assurance of this step will be essential to the interpretation of results.
  • Aged,
  • Analysis of Variance,
  • Canada,
  • Esophageal Neoplasms,
  • Health Care Surveys,
  • Humans,
  • Male,
  • Medical Oncology,
  • Observer Variation,
  • Radiotherapy Dosage,
  • Radiotherapy Planning,
  • Computer-Assisted,
  • Radiotherapy,
  • Conformal
Publication Date
September 1, 1998
Citation Information
Patricia Tai, Jake Van Dyk, Edward Yu, Jerry Battista, et al.. "Variability of Target Volume Delineation in Cervical Esophageal Cancer" International Journal of Radiation Oncology, Biology, Physics Vol. 42 Iss. 2 (1998)
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