title: Treatment Planning Studies in Patient Data With Scanned Carbon Ion Beams for Catheter-Free Ablation of Atrial Fibrillation.
abstract: BACKGROUND
  Catheter ablation with isolation of the pulmonary veins is a common treatment option for atrial fibrillation but still has insufficient success rates and carries several interventional risks. These treatment planning studies assessed if high-dose single fraction treatment with scanned carbon ions (12C) can be reliably delivered for AF ablation, while sparing risk structures and considering respiratory and contractile target motion.
  
  
  RESULTS
  Time resolved CT scans of complete respiratory and cardiac cycles of 9 and 5 patients, respectively, were obtained. Ablation lesions and organs at risk for beam delivery were contoured. Single fraction intensity-modulated particle therapy with target doses of 25 and 40 Gy were studied and motion influences on these deliveries mitigated. Respiration had a large influence on lesion displacement (≤ 2 cm). End expiration could be exploited as a stable gating window. Smaller, but less predictable, heartbeat displacements (< 6 mm) remained to be mitigated because cardiac contraction resulted in insufficient dose coverage (V95 < 90%) if uncompensated. Repeated irradiation (12C beam rescanning) during breath hold was used to accommodate contractile motion, resulting in good dose coverage. Dose depositions to all organs at risk were carefully examined and did not exceed values for X-ray cancer treatment.
  
  
  CONCLUSIONS
  Treatment planning of 12C with delivery of physical ionizing radiation doses that have been described to induce complete block is feasible for AF ablation, considering human anatomy, dose constraints, and encasing underlying motion patterns from respiration and cardiac contraction at the LA-PV junction into treatment planning.
authors.affiliation: Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Constantinescu
authors.affiliation: Mayo Clinic Translational Interventional Electrophysiology Laboratory, Rochester, Minnesota, USA.
authors.forename: H Immo
authors.initials: HI
authors.lastname: Lehmann
authors.affiliation: Mayo Clinic Translational Interventional Electrophysiology Laboratory, Rochester, Minnesota, USA.
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Packer
authors.affiliation: Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany.|Department of Radiation Oncology, Friedrich-Alexander University Erlangen-Nürnberg and University Hospital, Erlangen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bert
authors.affiliation: Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Durante
authors.affiliation: Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Graeff
mesh_terms: D001281:Atrial Fibrillation / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D017115:Catheter Ablation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D056973:Four-Dimensional Computed Tomography; D063193:Heavy Ion Radiotherapy / Q000379:methods*; D006801:Humans; D008297:Male; D010347:Patient Care Planning; D013223:Statistics as Topic / Q000379:methods*; D016896:Treatment Outcome
keywords: atrial fibrillation; carbon ion beam; catheter-free ablation; particle therapy; pulmonary vein isolation; ventricular tachycardia