title: Carbon ion radiotherapy for skull base chordoma.
abstract: OBJECTIVE
  To present the results of the clinical study of carbon ion radiotherapy (CIRT) for skull base and paracervical spine tumors at the National Institute of Radiological Sciences in Chiba, Japan.
  
  
  METHODS
  The study is comprised of three protocols: a pilot study, a phase I/II dose escalation study, and a phase II study. All the patients were treated by 16 fractions for 4 weeks with total doses of 48.0, 52.8, 57.6, and 60.8 Gy equivalents (GyE).
  
  
  RESULTS
  As a result of the dose escalation study of CIRT for skull base tumors, a dose fractionation of 60.8 GyE/16 fractions for 4 weeks was decided as the recommended dose because of acceptable normal tissue reactions and good local tumor control.
  
  
  CONCLUSIONS
  Preliminary results of the phase II clinical study of CIRT for skull base chordoma showed local control at 5 years at 100%, and normal tissues showed a mild reaction without any severe morbidity of important organs.
authors.affiliation: Research Center for Charged Particle Therapy Hospital, National Institute of Radiological Sciences (NIRS), Chiba, Japan.
authors.forename: Jun-Etsu
authors.initials: JE
authors.lastname: Mizoe
authors.forename: Azusa
authors.initials: A
authors.lastname: Hasegawa
authors.forename: Ryo
authors.initials: R
authors.lastname: Takagi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Bessho
authors.forename: Takeshi
authors.initials: T
authors.lastname: Onda
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Tsujii