title: Analysis of the variability among radiation oncologists in delineation of the postsurgical tumor bed based on 4D-CT.
abstract: OBJECTIVE
  This study investigated interobserver and intraobserver variability in radiation oncologists' definition of the tumor bed (TB) after breast-conserving surgery (BCS).
  
  
  RESULTS
  The TB volume, CVS and number of surgical clips were not significantly related to intraobserver variability. Moreover, no correlation was noted between CT slice thickness and interobserver variability (Δinter, DSCinter) in TB delineation, and no significant difference was noted among the three groups. The TB volume was negatively correlated with Δinter. DSCinter improved significantly with increased TB volume and decreased Δinter. DSCinter also increased significantly in patients with a CVS of 3 to 5 compared with patients with a CVS of 1 to 2. DSCinter was thus positively correlated with the CVS, with a correlation coefficient of 0.451. The use of 7 to 9 surgical clips neither decreased Δinter nor increased DSCinter.
  
  
  METHODS
  Five or more surgical clips were placed at the TB during lumpectomy. The TB was delineated on the end expiration scan. The data were stratified based on the cavity visualization score (CVS), CT slice thickness and surgical clip number. The Dice similarity coefficient (DSC) and inter(intra)observer variability (Δinter and Δintra) in different groups were evaluated and compared.
  
  
  CONCLUSIONS
  Inter(intra)observer variability in TB delineation was decreased for breast cancer patients implanted with 5 or more surgical clips in the cohort with a higher CVS and a larger TB. The use of more than 6 surgical clips did not significantly improve TB delineation, so 5 to 6 surgical clips are likely adequate to delineate the TB.
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital affiliated to Shandong University, Shandong Academy of Medical Sciences, Jinan, Shandong province, China, 250117.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital affiliated to Shandong University, Shandong Academy of Medical Sciences, Jinan, Shandong province, China, 250117.
authors.forename: Jianbin
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital affiliated to Shandong University, Shandong Academy of Medical Sciences, Jinan, Shandong province, China, 250117.
authors.forename: Jun
authors.initials: J
authors.lastname: Xing
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital affiliated to Shandong University, Shandong Academy of Medical Sciences, Jinan, Shandong province, China, 250117.
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital affiliated to Shandong University, Shandong Academy of Medical Sciences, Jinan, Shandong province, China, 250117.
authors.forename: Qian
authors.initials: Q
authors.lastname: Shao
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital affiliated to Shandong University, Shandong Academy of Medical Sciences, Jinan, Shandong province, China, 250117.
authors.forename: Tingyong
authors.initials: T
authors.lastname: Fan
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital affiliated to Shandong University, Shandong Academy of Medical Sciences, Jinan, Shandong province, China, 250117.
authors.forename: Bing
authors.initials: B
authors.lastname: Guo
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital affiliated to Shandong University, Shandong Academy of Medical Sciences, Jinan, Shandong province, China, 250117.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Liu
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery; D006801:Humans; D015412:Mastectomy, Segmental / Q000295:instrumentation / Q000379:methods; D008875:Middle Aged; D015588:Observer Variation; D000072378:Radiation Oncologists / Q000592:standards*; D012307:Risk Factors; D013525:Surgical Instruments; D014057:Tomography, X-Ray Computed / Q000379:methods*; D047368:Tumor Burden; D055815:Young Adult
keywords: CT slice thickness; breast-conserving treatment; cavity visualization score; surgical clip number; tumor bed delineation