title: Target position uncertainty during visually guided deep-inspiration breath-hold radiotherapy in locally advanced lung cancer.
abstract: The purpose of this study was to estimate the uncertainty in voluntary deep-inspiration breath-hold (DIBH) radiotherapy for locally advanced non-small cell lung cancer (NSCLC) patients.
  
  
  
  Perpendicular fluoroscopic movies were acquired in free breathing (FB) and DIBH during a course of visually guided DIBH radiotherapy of nine patients with NSCLC. Patients had liquid markers injected in mediastinal lymph nodes and primary tumours. Excursion, systematic- and random errors, and inter-breath-hold position uncertainty were investigated using an image based tracking algorithm.
  
  
  
  A mean reduction of 2-6mm in marker excursion in DIBH versus FB was seen in the anterior-posterior (AP), left-right (LR) and cranio-caudal (CC) directions. Lymph node motion during DIBH originated from cardiac motion. The systematic- (standard deviation (SD) of all the mean marker positions) and random errors (root-mean-square of the intra-BH SD) during DIBH were 0.5 and 0.3mm (AP), 0.5 and 0.3mm (LR), 0.8 and 0.4mm (CC), respectively. The mean inter-breath-hold shifts were -0.3mm (AP), -0.2mm (LR), and -0.2mm (CC).
  
  
  
  Intra- and inter-breath-hold uncertainty of tumours and lymph nodes were small in visually guided breath-hold radiotherapy of NSCLC. Target motion could be substantially reduced, but not eliminated, using visually guided DIBH.
authors.affiliation: Department of Oncology, Section of Radiotherapy, 3994, Rigshospitalet, Copenhagen, Denmark; Niels Bohr Institute, University of Copenhagen, Denmark. Electronic address: Jonas.Scherman-Rydhog@Skane.se.
authors.forename: Jonas
authors.initials: J
authors.lastname: Scherman Rydhög
authors.affiliation: Department of Oncology, Section of Radiotherapy, 3994, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Steen
authors.initials: S
authors.lastname: Riisgaard de Blanck
authors.affiliation: Department of Oncology, Section of Radiotherapy, 3994, Rigshospitalet, Copenhagen, Denmark; Niels Bohr Institute, University of Copenhagen, Denmark.
authors.forename: Mirjana
authors.initials: M
authors.lastname: Josipovic
authors.affiliation: DTU Nanotech, Department of Micro-and Nanotechnology, Center for Nanomedicine and Theranostics, Technical University of Denmark, Denmark; Nanovi Radiotherapy A/S, Denmark.
authors.forename: Rasmus
authors.initials: R
authors.lastname: Irming Jølck
authors.affiliation: Department of Clinical Medicine, Bispebjerg Hospital, Copenhagen, Denmark.
authors.forename: Klaus Richter
authors.initials: KR
authors.lastname: Larsen
authors.affiliation: Department of Internal Medicine, Zealand University Hospital, Roskilde, Denmark; Copenhagen Academy for Medical Education and Simulation (CAMES), Rigshospitalet, Denmark.
authors.forename: Paul
authors.initials: P
authors.lastname: Clementsen
authors.affiliation: DTU Nanotech, Department of Micro-and Nanotechnology, Center for Nanomedicine and Theranostics, Technical University of Denmark, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lars Andersen
authors.affiliation: Department of Oncology, Aarhus University Hospital, Denmark.
authors.forename: Per Rugaard
authors.initials: PR
authors.lastname: Poulsen
authors.affiliation: Department of Oncology, Section of Radiotherapy, 3994, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Gitte
authors.initials: G
authors.lastname: Fredberg Persson
authors.affiliation: Department of Oncology, Section of Radiotherapy, 3994, Rigshospitalet, Copenhagen, Denmark; Niels Bohr Institute, University of Copenhagen, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Munck Af Rosenschold
mesh_terms: D062485:Breath Holding; D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy*; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D035501:Uncertainty
keywords: Image based tracking; Image-guided radiotherapy; Liquid fiducial marker