title: Dose accumulation during vaginal cuff brachytherapy based on rigid/deformable registration vs. single plan addition.
abstract: OBJECTIVE
  To compare dose summation using a single plan (SP) approach for vaginal cuff brachytherapy (VBT) against dose summation after a rigid or deformable registration for each VBT fraction, in women with early stage endometrial cancer receiving postoperative VBT.
  
  
  METHODS
  A retrospective analysis of 19 patients who received VBT as the sole adjuvant treatment was undertaken. For the purposes of the study, every VBT fraction was re-segmented and re-planned under the same conditions. CT-planning images were registered, initially following a rigid method and then using deformable registration. The transformation vectors were reused to warp the dose files, followed by the dose summation. Three dose accumulation scenarios were studied: (1) an SP approach, (2) a rigid dose warping summation (RDWS), (3) a deformable dose warping summation (DDWS). Each scenario was analyzed for 3 and 5 fractions to evaluate the effect of fractionation. D0.1cc, D1cc, D2cc, D5cc, D5%, and Dmean values were compared for organs at risk, such as the rectum and bladder.
  
  
  RESULTS
  No statistical significances were observed in rectal parameters between SP and RDWS or between SP and DDWS. Significant SP, RDWS and DDWS Dmean, D0.1cc, and D2cc metric differences for the 5 fractions bladder scenario were observed (p = 0.0242, 0.0196, and 0.0242, respectively).
  
  
  CONCLUSIONS
  A multi-image planning procedure for a VBT course leads to limited differences between different summation methods. SP is an effective and acceptable surrogate for absorbed doses in organs at risk.
authors.affiliation: Department of Radiation Oncology, Complejo Hospitalario Universitario de Albacete (CHUA), Albacete, Spain. Electronic address: ssabaterm@gmail.com.
authors.forename: Sebastia
authors.initials: S
authors.lastname: Sabater
authors.affiliation: Department of Radiation Oncology, Complejo Hospitalario Universitario de Albacete (CHUA), Albacete, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Andres
authors.affiliation: Department of Radiation Oncology, Complejo Hospitalario Universitario de Albacete (CHUA), Albacete, Spain.
authors.forename: Marimar
authors.initials: M
authors.lastname: Sevillano
authors.affiliation: Department of Radiation Oncology, Complejo Hospitalario Universitario de Albacete (CHUA), Albacete, Spain.
authors.forename: Roberto
authors.initials: R
authors.lastname: Berenguer
authors.affiliation: C.S. General Ricardos, Area 11, Madrid, Spain.
authors.forename: Santiago
authors.initials: S
authors.lastname: Machin-Hamalainen
authors.affiliation: Department of Radiation Oncology, Hospital Universitari Sant Joan, Reus, Spain.
authors.forename: Meritxell
authors.initials: M
authors.lastname: Arenas
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000379:methods*; D019583:Dose Fractionation, Radiation; D016889:Endometrial Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008875:Middle Aged; D058958:Organs at Risk; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D018714:Radiotherapy, Adjuvant; D012007:Rectum; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D001743:Urinary Bladder; D014621:Vagina
keywords: Cylinder; Deformable registration; Dose accumulation; Endometrium; Rigid registration