title: Commissioning of the 4-D treatment delivery system for organ motion management in synchrotron-based scanning ion beams.
abstract: OBJECTIVE
  The aim of this work was the commissioning of delivery procedures for the treatment of moving targets in scanning pencil beam hadrontherapy.
  
  
  METHODS
  EBT3 films fixed to the Anzai Respiratory Phantom were exposed to carbon ion scanned homogeneous fields (E=332MeV/u). To evaluate the interplay effect, field size and flatness for 3 different scenarios were compared to static condition: gated irradiation or repainting alone and combination of both. Respiratory signal was provided by Anzai pressure sensor or optical tracking system (OTS). End-exhale phase and 1s gating window were chosen (2.5mm residual motion). Dose measurements were performed using a PinPoint ionization chamber inserted into the Brainlab ET Gating Phantom. A sub-set of tests was also performed using proton beams.
  
  
  RESULTS
  The combination of gating technique and repainting (N=5) showed excellent results (6.1% vs 4.3% flatness, identical field size and dose deviation within 1.3%). Treatment delivery time was acceptable. Dose homogeneity for gated irradiation alone was poor. Both Anzai sensor and OTS appeared suitable for providing respiratory signal. Comparisons between protons and carbon ions showed that larger beam spot sizes represent more favorable condition for minimizing motion effect.
  
  
  CONCLUSIONS
  Results of measurements performed on different phantoms showed that the combination of gating and layered repainting is suitable to treat moving targets using scanning ion beams. Abdominal compression using thermoplastic masks, together with multi-field planning approach and multi-fractionation, have also been assessed as additional strategies to mitigate the effect of patient respiration in the clinical practice.
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy. Electronic address: mario.ciocca@cnao.it.
authors.forename: Mario
authors.initials: M
authors.lastname: Ciocca
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Mirandola
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Molinelli
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Russo
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Mastella
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vai
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mairani
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Magro
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Pella
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Donetti
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Valvo
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy; Istituto Europeo di Oncologia, via Ripamonti 435, 20100 Milano, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Fossati
authors.affiliation: Fondazione CNAO, Strada Campeggi 53, 27100 Pavia, Italy; Dipartimento di Elettronica Informazione e Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Baroni
mesh_terms: D006801:Humans; D009068:Movement; D019047:Phantoms, Imaging; D061766:Proton Therapy / Q000295:instrumentation*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012119:Respiration; D017356:Synchrotrons
keywords: Ion beam radiotherapy; Motion mitigation; Pencil beam scanning; Respiratory gating