title: Assessment of set-up variability during deep inspiration breath hold radiotherapy for breast cancer patients by 3D-surface imaging.
abstract: OBJECTIVE
  To quantify set-up uncertainties during voluntary deep inspiration breath hold (DIBH) radiotherapy using 3D-surface imaging in patients with left sided breast cancer.
  
  
  METHODS
  Nineteen patients were included. Cone-beam CT-scan (CBCT) was used for online set-up correction while patients were instructed to perform a voluntary DIBH. The reproducibility of the DIBH during treatment was monitored with 2D-fluoroscopy and portal imaging. Simultaneously, a surface imaging system was used to capture 3D-surfaces throughout CBCT acquisition and delivery of treatment beams. Retrospectively, all captured surfaces were registered to the planning-CT surface. Interfraction, intra-fraction and intra-beam set-up variability were quantified in left-right, cranio-caudal and anterior-posterior direction.
  
  
  RESULTS
  Inter-fraction systematic (Σ) and random (σ) translational errors (1SD) before and after set-up correction were between 0.20-0.50 cm and 0.09-0.22 cm, respectively, whereas rotational Σ and σ errors were between 0.08 and 1.56°. The intra-fraction Σ and σ errors were ≤ 0.14 cm and ≤ 0.47°. The intra-beam SD variability was ≤ 0.08 cm and ≤ 0.28° in all directions.
  
  
  CONCLUSIONS
  Quantification of 3D set-up variability in DIBH RT showed that patients are able to perform a very stable and reproducible DIBH within a treatment fraction. However, relatively large inter-fraction variability requires online image guided set-up corrections.
authors: Department of Radiation Oncology, The Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
authors: Anja
authors: A
authors: Betgen
authors: Tanja
authors: T
authors: Alderliesten
authors: Jan-Jakob
authors: JJ
authors: Sonke
authors: Corine
authors: C
authors: van Vliet-Vroegindeweij
authors: Harry
authors: H
authors: Bartelink
authors: Peter
authors: P
authors: Remeijer
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000532:radiotherapy*; D062485:Breath Holding; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008875:Middle Aged; D061106:Radiotherapy Setup Errors / Q000517:prevention & control; D061089:Radiotherapy, Image-Guided / Q000379:methods*