title: Improving the definition of tumor bed boost with the use of surgical clips and image registration in breast cancer patients.
abstract: OBJECTIVE
  To evaluate the accuracy of a boost technique.
  
  
  METHODS
  Twenty-two patients underwent tumorectomy with placement of two or more clips in the surgical cavity before breast remodeling. Preoperative and postoperative computed tomography scans, with match-point registration, were performed on all patients. The relationship between the location of the gross tumor volume (GTV), defined on the preoperative scan, and clip clinical target volume (CTV) (clips with a 5-mm margin on the postoperative scan) was then studied, by use of commercial volume analysis software.
  
  
  RESULTS
  Of the patients, 4 had two clips, 2 had three clips, 8 had four clips, and 8 had five clips. The median GTV was 1.06 mL (range, 0.2-5.3 mL); clip CTV ranged from 2.4 to 21.5 mL. Volumetric analysis showed that in 7 cases (32%), there was no intersection between the GTV and the clip CTV, with the following distribution: 4 patients with two clips, 1 patient with three clips, 1 patient with four clips, and 1 patient with five clips. The common contoured volume was defined as the percent ratio between the intersection of the GTV and clip CTV and the GTV. It was found to be significantly increased if three or more clips were used vs. only two clips (common contoured volume, 35.45% vs. 0.73%; p = 0.028). Finally, the GTV and clip CTV volume relationship can be presented as follows: 12.5% to 33% overlap in 8 patients (36.4%), 50% to 75% in 5 patients (22.7%), and greater than 90% in 2 patients (9%).
  
  
  CONCLUSIONS
  The use of three or more clips during tumorectomy increases the accuracy of tumor bed delineation.
authors.affiliation: Department of Radiation Oncology, Institut Curie, Paris, France. youlia.kirova@curie.net
authors.forename: Youlia M
authors.initials: YM
authors.lastname: Kirova
authors.forename: Pablo
authors.initials: P
authors.lastname: Castro Pena
authors.forename: Tarek
authors.initials: T
authors.lastname: Hijal
authors.forename: Nathalie
authors.initials: N
authors.lastname: Fournier-Bidoz
authors.forename: Fatima
authors.initials: F
authors.lastname: Laki
authors.forename: Brigitte
authors.initials: B
authors.lastname: Sigal-Zafrani
authors.forename: Rémi
authors.initials: R
authors.lastname: Dendale
authors.forename: Marc A
authors.initials: MA
authors.lastname: Bollet
authors.forename: Francois
authors.initials: F
authors.lastname: Campana
authors.forename: Alain
authors.initials: A
authors.lastname: Fourquet
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D005260:Female; D057918:Fiducial Markers; D006801:Humans; D015412:Mastectomy, Segmental; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D013525:Surgical Instruments / Q000706:statistics & numerical data; D047368:Tumor Burden