title: Technical approach to individualized respiratory-gated carbon-ion therapy for mobile organs.
abstract: We propose a strategy of individualized image acquisitions and treatment planning for respiratory-gated carbon-ion therapy. We implemented it in clinical treatments for diseases of mobile organs such as lung cancers at the Gunma University Heavy Ion Medical Center in June 2010. Gated computed tomography (CT) scans were used for treatment planning, and four-dimensional (4D) CT scans were used to evaluate motion errors within the gating window to help define the internal margins (IMs) and planning target volume for each patient. The smearing technique or internal gross tumor volume (IGTV = GTV + IM), where the stopping power ratio was replaced with the tumor value, was used for range compensation of moving targets. Dose distributions were obtained using the gated CT images for the treatment plans. The influence of respiratory motion on the dose distribution was verified with the planned beam settings using 4D CT images at some phases within the gating window before the adoption of the plan. A total of 14 lung cancer patients were treated in the first year. The planned margins with the proposed method were verified with clinical X-ray set-up images by deriving setup and internal motion errors. The planned margins were considered to be reasonable compared with the errors, except for large errors observed in some cases.
authors.affiliation: Gunma University Heavy Ion Medical Center, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan. tashiro@gunma-u.ac.jp
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Tashiro
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ishii
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Koya
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Okada
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kurosawa
authors.forename: Keisuke
authors.initials: K
authors.lastname: Arai
authors.forename: Satoshi
authors.initials: S
authors.lastname: Abe
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Ohashi
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Shimada
authors.forename: Ken
authors.initials: K
authors.lastname: Yusa
authors.forename: Tatsuaki
authors.initials: T
authors.lastname: Kanai
authors.forename: Satoru
authors.initials: S
authors.lastname: Yamada
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Kawamura
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ebara
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ohno
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
mesh_terms: D002244:Carbon / Q000627:therapeutic use*; D056973:Four-Dimensional Computed Tomography; D063193:Heavy Ion Radiotherapy; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D058958:Organs at Risk / Q000528:radiation effects; D056888:Patient Positioning; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D015656:Respiratory Mechanics
chemical_list: D002244:Carbon