title: In silico comparison of photons versus carbon ions in single fraction therapy of lung cancer.
abstract: OBJECTIVE
  Stereotactic body image guided radiation therapy (SBRT) shows good results for lung cancer treatment. Better normal tissue sparing might be achieved with scanned carbon ion therapy (PT). Therefore an in silico trial was conducted to find potential advantages of and patients suited for PT.
  
  
  METHODS
  For 19 patients treated with SBRT, PT plans were calculated on 4D-CTs with simulated breathing motion. Prescribed single fraction dose was 24Gy and OAR constraints used for photon planning were respected. Motion was mitigated by rescanning and range-adapted ITVs. Doses were compared to the original SBRT plans.
  
  
  RESULTS
  CTV coverage was the same in SBRT and PT. The field-specific PTV including range margins for PT was 1.5 (median, 25-75% 1.3-2.1) times larger than for SBRT. Nevertheless, maximum point dose and mean dose in OARs were higher in SBRT by 2.8 (1.6-3.7) Gy and 0.7 (0.3-1.6) Gy, respectively. Patients with a CTV >2.5cc or with multiple lung lesions showed larger differences in OAR doses in favor of PT.
  
  
  CONCLUSIONS
  Patients receive less dose in critical OARs such as heart, spinal cord, esophagus, trachea and aorta with PT, while maintaining the same target coverage. Patients with multiple or larger lesions are particularly suited for PT.
authors: GSI Helmholtz Centre for Heavy Ion Research, Planckstr. 1, 64291 Darmstadt, Germany. Electronic address: k.anderle@gsi.de.
authors: Kristjan
authors: K
authors: Anderle
authors: Champalimaud Centre for the Unknown, Av. Brasília, 1400-038 Lisbon, Portugal.
authors: Joep
authors: J
authors: Stroom
authors: Champalimaud Centre for the Unknown, Av. Brasília, 1400-038 Lisbon, Portugal.
authors: Nuno
authors: N
authors: Pimentel
authors: Champalimaud Centre for the Unknown, Av. Brasília, 1400-038 Lisbon, Portugal.
authors: Carlo
authors: C
authors: Greco
authors: GSI Helmholtz Centre for Heavy Ion Research, Planckstr. 1, 64291 Darmstadt, Germany.
authors: Marco
authors: M
authors: Durante
authors: GSI Helmholtz Centre for Heavy Ion Research, Planckstr. 1, 64291 Darmstadt, Germany.
authors: Christian
authors: C
authors: Graeff
mesh_terms: D002244:Carbon / Q000737:chemistry*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007477:Ions; D008175:Lung Neoplasms / Q000532:radiotherapy*; D009038:Motion; D017785:Photons; D011878:Radiotherapy / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D061089:Radiotherapy, Image-Guided; D015203:Reproducibility of Results; D012119:Respiration
chemical_list: D007477:Ions; D002244:Carbon
keywords: Lung cancer; Motion mitigation; Particle therapy; SDRT; Single fraction