title: Displacement of the lumpectomy cavity defined by surgical clips and seroma based on 4D-CT scan for external-beam partial breast irradiation after breast-conserving surgery: a comparative study.
abstract: OBJECTIVE
  To compare the displacements of the lumpectomy cavity delineated by the surgical clips and the seroma based on four-dimensional CT (4D-CT) for external-beam partial breast irradiation (EB-PBI) after breast-conserving surgery (BCS).
  
  
  METHODS
  14 breast cancer patients after BCS were recruited for EB-PBI and undertook 4D-CT simulation. On the 10 sets of the 4D-CT images, all the surgical clips in the cavity were delineated. The gross tumour volume (GTV) formed by the clips, the seroma, and both the clips and the seroma were defined as GTVc, GTVs and GTVc+s, respectively. The displacements of the centre of mass (COM) of the clips, GTVc, GTVs, GTVc+s and the selected clips in the three-dimensional (3D) directions were recorded and compared.
  
  
  RESULTS
  In the left-right, anterior-posterior and superior-inferior directions, the displacements were 2.20, 1.80 and 2.70 mm for the clip COM; 0.90, 1.05 and 1.20 mm for GTVc; 0.80, 1.05 and 0.80 mm for GTVs; and 0.90, 1.20 and 1.40 mm for GTVc+s, respectively. In the 3D directions, the displacements of the clip COM were greater than the GTVc, GTVs, GTVc+s, and the displacements of the clip COM, GTVc+s, GTVc and GTVs were significantly greater than the displacements of the selected clips (p<0.05).
  
  
  CONCLUSIONS
  The displacements of the clip COM were greater than that of the GTVc, GTVs, GTVc+s and the four selected clips. The optimal internal target volume should be defined based on the boundary displacements.
  
  
  CONCLUSIONS
  When the GTV was delineated using the clips and/or the seroma, there was displacement difference between the lumpectomy cavity centre and the boundary for the EB-PBI. The optimal internal target volume should be defined based on the boundary displacements of the lumpectomy cavity.
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital and Institute, Jinan, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Ding
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.forename: T
authors.initials: T
authors.lastname: Fan
authors.forename: M
authors.initials: M
authors.lastname: Xu
authors.forename: Q
authors.initials: Q
authors.lastname: Shao
authors.forename: Z
authors.initials: Z
authors.lastname: Ma
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery*; D005260:Female; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D018714:Radiotherapy, Adjuvant; D049291:Seroma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery*; D013525:Surgical Instruments