title: Establishing stereotactic body radiotherapy with flattening filter free techniques in the treatment of pulmonary lesions - initial experiences from a single institution.
abstract: BACKGROUND
  Stereotactic body radiotherapy (SBRT) using flattening filter free (FFF)-techniques has been increasingly applied during the last years. However, clinical studies investigating this emerging technique are still rare. Hence, we analyzed toxicity and clinical outcome of pulmonary SBRT with FFF-techniques and performed dosimetric comparison to conventional techniques using flattening filters (FF).
  
  
  METHODS
  Between 05/2014 and 06/2015, 56 consecutive patients with 61 pulmonary lesions were treated with SBRT in FFF-mode. Central lesions received 8 × 7.5 Gy delivered to the conformally enclosing 80 %-isodose, while peripheral lesions were treated with 3 × 15 Gy, prescribed to the 65 %-isodose. Early and late toxicity (after 6 months) as well as initial clinical outcomes were evaluated. Furthermore, [deleted] plan quality and efficiency were evaluated by analyzing conformity, beam- on and total treatment delivery times in comparison to plans with FF-dose application.
  
  
  RESULTS
  Median follow-up time was 9.3 months (range 1.5-18.0 months). Early toxicity was low with only 5 patients (8.9 %) reporting CTCAE 2° or higher side-effects. Only one patient (1.8 %) was diagnosed with radiation-induced pneumonitis CTCAE 3°, while 2 (3.6 %) patients suffered from pneumonitis CTCAE 2°. After 6 months, no toxicity greater than CTCAE 2° was reported. 1-year local progression-free survival, distant progression-free survival and overall survival were 92.8 %, 78.0 %, and 94.4 %, respectively. While plan quality was similar for FFF- and FF-plans in respect to conformity (p = 0.275), median beam-on time as well as total treatment time were significantly reduced for SBRT in FFF-mode compared to FF-mode (p ≤ 0.001, p ≤ 0.001).
  
  
  CONCLUSIONS
  Patient treatment with SBRT using FFF-techniques is safe and provides promising clinical results with only modest toxicity at significantly increased dose delivery speed.
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.|Heidelberg Institute of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Rieber
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.|Heidelberg Institute of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Eric
authors.initials: E
authors.lastname: Tonndorf-Martini
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.|Heidelberg Institute of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Schramm
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.|Heidelberg Institute of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Rhein
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.|Heidelberg Institute of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Laila
authors.initials: L
authors.lastname: König
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.|Heidelberg Institute of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Adeberg
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.|Heidelberg Institute of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Meyerhof
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.|Heidelberg Institute of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Angela
authors.initials: A
authors.lastname: Mohr
authors.affiliation: Translational Research Unit, Thoraxklinik, Heidelberg University, Germany Translational Lung Research Centre Heidelberg (TLRC-H), Member of the German Centre for Lung Research (DZL), Heidelberg, Germany.|Department of Pneumology, Thoraxklinik, Heidelberg University, Heidelberg, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Kappes
authors.affiliation: Department of Pneumology, Thoraxklinik, Heidelberg University, Heidelberg, Germany.|Department of Thoracic Surgery, Thoraxklinik, Heidelberg University, Heidelberg, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Hoffmann
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.|Heidelberg Institute of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Debus
authors.affiliation: Department of Radiation Oncology, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. stefan.rieken@med.uni-heidelberg.de.|Heidelberg Institute of Radiation Oncology, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. stefan.rieken@med.uni-heidelberg.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Rieken
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D005374:Filtration; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000556:secondary / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010315:Particle Accelerators / Q000295:instrumentation*; D011379:Prognosis; D011446:Prospective Studies; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D015996:Survival Rate