title: Supine craniospinal irradiation in pediatric patients by proton pencil beam scanning.
abstract: Proton therapy is the emerging treatment modality for craniospinal irradiation (CSI) in pediatric patients. Herein, special methods adopted for CSI at proton Therapy Center of Trento by pencil beam scanning (PBS) are comprehensively described.
  
  
  
  Twelve pediatric patients were treated by proton PBS using two/three isocenters. Special methods refer to: (i) patient positioning in supine position on immobilization devices crossed by the beams; (ii) planning field-junctions via the ancillary-beam technique; (iii) achieving lens-sparing by three-beams whole-brain-irradiation; (iv) applying a movable-snout and beam-splitting technique to reduce the lateral penumbra. Patient-specific quality assurance (QA) program was performed using two-dimensional ion chamber array and γ-analysis. Daily kilovoltage alignment was performed.
  
  
  
  PBS allowed to obtain optimal target coverage (mean D98%>98%) with reduced dose to organs-at-risk. Lens sparing was obtained (mean D1∼730cGyE). Reducing lateral penumbra decreased the dose to the kidneys (mean Dmean<600cGyE). After kilovoltage alignment, potential dose deviations in the upper and lower junctions were small (average 0.8% and 1.2% respectively). Due to imperfect modeling of range shifter, QA showed better agreements between measurements and calculations at depths >4cm (mean γ>95%) than at depths<4cm.
  
  
  
  The reported methods allowed to effectively perform proton PBS CSI.
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy. Electronic address: paolofarace@gmail.com.
authors.forename: Paolo
authors.initials: P
authors.lastname: Farace
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Bizzocchi
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Righetto
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Fellin
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Fracchiolla
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Lorentini
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy.
authors.forename: Lamberto
authors.initials: L
authors.lastname: Widesott
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Algranati
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Rombi
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy.
authors.forename: Sabina
authors.initials: S
authors.lastname: Vennarini
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Amichetti
authors.affiliation: Proton Therapy Center, Hospital of Trento, Azienda Provinciale per I Servizi Sanitari (APSS), Italy; Trento Institute for Fundamental Physics and Applications (TIFPA), National Institute of Nuclear Physics (INFN), Trento, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Schwarz
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D061888:Craniospinal Irradiation / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D058958:Organs at Risk; D056888:Patient Positioning; D061766:Proton Therapy / Q000379:methods*; D011785:Quality Assurance, Health Care; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D061089:Radiotherapy, Image-Guided
keywords: CSI; Craniospinal; Medulloblastoma; Pencil beam; Proton