title: [Comparison of the volume and localization of internal gross target volume and planning target volume delineated by clips and seroma based on 4D-CT scan for external-beam partial breast irradiation after breast conserving surgery].
abstract: OBJECTIVE
  To explore the differences in volume and localization of the internal gross target volume and planning target volume delineated by clips and/or seroma based on four-dimensional computed tomography (4D-CT) during free-breathing in breast cancer patients after breast conserving surgery.
  
  
  METHODS
  Fifteen breast cancer patients after breast-conserving surgery (BCS) were recruited for external-beam partial breast irradiation (EB-PBI). On the ten sets CT images, the gross tumor volumes (GTV) formed by the clips, the seroma, and both the clips and seroma were delineated and defined as GTVc, GTVs and GTVc+s, respectively. Ten GTVc, GTVs and GTVc+s on the ten sets CT images produced the IGTVc, IGTVs, IGTVc+s. The PTVc, PTVs, PTVc+s were created by adding 15 mm to the IGTVc, IGTVs, IGTVc+s, respectively. The IGTV and PTV volume and distance between the centers of IGTVc, IGTVs, IGTVc+s and PTVc, PTVs, PTVc+s were all recorded. Conformity index (CI) and degree of inclusion (DI) were calculated for IGTV/IGTV and PTV/PTV, respectively.
  
  
  RESULTS
  The volume of IGTVc+s[(35.73 ± 19.77) cm³] was significantly larger than the IGTVc [(28.35 ± 17.54) cm³] and IGTVs [(24.19 ± 21.53) cm³] (P < 0.05), and the volume of PTVc+s [(191.59 ± 69.74) cm³] was significantly larger than that of the PTVc [(161.53 ± 61.07) cm³] and PTVs [(148.98 ± 62.22)cm³] (P < 0.05). There were significant differences between the DIs of IGTVc in IGTVc+s and IGTVc+s in IGTVc, the DIs of IGTVs in IGTVc+s and IGTVc+s in IGTVs, the DIs of PTVc in PTVc+s and PTVc+s in PTVc, and the DIs of PTVs vs. PTVc+s and PTVc+s in PTVs (P < 0.05 for all). The CI of IGTVc/IGTVc+s (0.63 ± 0.14) and the CI of IGTVs/IGTVc+s (0.54 ± 0.17) were significant larger than that of the CI of IGTVc/IGTVs (0.40 ± 0.14)(P < 0.05). There were non-significant differences among the CI of PTVc/PTVs, PTVc/PTVc+s and PTVs/PTVc+s (0.73 ± 0.12, 0.78 ± 0.13 vs. 0.75 ± 0.17). The DIs and CIs of IGTV/IGTV and PTV/PTV were negatively correlated with their centroid distance (P < 0.05).
  
  
  CONCLUSIONS
  There are volume difference and spatial mismatch between the target volumes delineated on the basis of surgical clips and seroma. The DI and CI between the PTVs are larger than that between the IGTV. External-beam partial breast irradiation should be implemented based on the PTV that is defined based on both seroma and surgical clips.
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital, Jinan 250117, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital, Jinan 250117, China. Email: lijianbin@msn.com.
authors.forename: Jianbin
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital, Jinan 250117, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital, Jinan 250117, China.
authors.forename: Suzhen
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital, Jinan 250117, China.
authors.forename: Jinzhi
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, Shandong Cancer Hospital, Jinan 250117, China.
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Ma
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D005260:Female; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D015412:Mastectomy, Segmental / Q000379:methods*; D011879:Radiotherapy Dosage; D012119:Respiration; D049291:Seroma / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D013525:Surgical Instruments