title: Treating patients with real-time tumor tracking using the Vero gimbaled linac system: implementation and first review.
abstract: OBJECTIVE
  To report on the first clinical application of a real-time tumor tracking (RTTT) solution based on the Vero SBRT gimbaled linac system for treatment of moving tumors.
  
  
  METHODS
  A first group of 10 SBRT patients diagnosed with NSCLC or oligometastatic disease in lung or liver was treated with the RTTT technique. The PTV volumes and OAR exposure were benchmarked against the widely used ITV approach. Based on data acquired during execution of RTTT treatments, a first review was performed of the process.
  
  
  RESULTS
  The 35% PTV volume reduction with RTTT of the studied single lesions SBRT irradiations of small target volumes is expected to result in a small (<1%) reduction of lung or liver NTCP. A GTV-PTV margin of 5.0mm was applied for treatment planning of RTTT. From patient data on residual geometric uncertainties, a CTV-PTV margin of 3.2mm was calculated. Reduction of the GTV-PTV margin below 5.0mm without better understanding of biological definition of tumor boundaries was discouraged. Total treatment times were reduced to 34.4 min on average.
  
  
  CONCLUSIONS
  A considerable PTV volume reduction was achieved applying RTTT and time efficiency for respiratory correlated SBRT was reestablished with Vero RTTT.
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels; Vrije Universiteit Brussel, Medical Imaging and Physical Sciences Group, Faculty of Medicine and Pharmacy; Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium. Electronic address: tom.depuydt@uzleuven.be.
authors: Tom
authors: T
authors: Depuydt
authors: Vrije Universiteit Brussel, Medical Imaging and Physical Sciences Group, Faculty of Medicine and Pharmacy.
authors: Kenneth
authors: K
authors: Poels
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels; Vrije Universiteit Brussel, Medical Imaging and Physical Sciences Group, Faculty of Medicine and Pharmacy.
authors: Dirk
authors: D
authors: Verellen
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels.
authors: Benedikt
authors: B
authors: Engels
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels.
authors: Christine
authors: C
authors: Collen
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels.
authors: Manuela
authors: M
authors: Buleteanu
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels.
authors: Robbe
authors: R
authors: Van den Begin
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels.
authors: Marlies
authors: M
authors: Boussaer
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels.
authors: Michael
authors: M
authors: Duchateau
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels.
authors: Thierry
authors: T
authors: Gevaert
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels; Vrije Universiteit Brussel, Medical Imaging and Physical Sciences Group, Faculty of Medicine and Pharmacy.
authors: Guy
authors: G
authors: Storme
authors: Radiotherapy Department, UZ Brussel, Vrije Universiteit Brussel, Brussels; Vrije Universiteit Brussel, Medical Imaging and Physical Sciences Group, Faculty of Medicine and Pharmacy.
authors: Mark
authors: M
authors: De Ridder
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D057918:Fiducial Markers; D056973:Four-Dimensional Computed Tomography / Q000379:methods; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology; D008113:Liver Neoplasms / Q000175:diagnosis / Q000601:surgery*; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology; D008175:Lung Neoplasms / Q000175:diagnosis / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D058958:Organs at Risk / Q000000981:diagnostic imaging / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods; D016634:Radiosurgery / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results
keywords: Organ motion; Stereotactic body radiation therapy; Tumor tracking