@misc{oai:repo.qst.go.jp:00071758,
 author = {Inaniwa, Taku and Kanematsu, Nobuyuki and Hara, Yousuke and Furukawa, Takuji and Fukahori, Mai and Nakao, Minoru and Shirai, Toshiyuki and 稲庭 拓 and 兼松 伸幸 and 原 洋介 and 古川 卓司 and 深堀 麻衣 and 中尾 稔 and 白井 敏之},
 month = {Jun},
 note = {Objective:
The challenging issues for the treatment planning of scanned carbon-ion (C-ion) therapy are how to calculate the dose distribution accurately including the contributions from large angle-scattered fragments, how to reduce the memory space to store the dose kernel of the individual pencil beam, and how to shorten the computation time for the dose optimization and the calculation.
Methods:
To calculate the dose contributions from the fragments, the transverse dose profile of the scanned C-ion beam is modeled with the superposition of three Gaussian distributions. The development of the pencil beams belong to the first-Gaussian component is calculated analytically based on the Fermi-eyges theory, while those belong to the second and third components are transported empirically using the measured beam widths in a water phantom. To reduce the memory space for the kernels, we store doses only in the regions of interest (ROIs) considered in the dose optimization. For the final dose calculation within the whole patient’s body, we applied the pencil beam redefinition algorithm (PBRA). With these techniques, the three-Gaussian beam model can be applied not only to the final dose calculation but also to the dose optimization in the treatment planning of scanned C-ion therapy. To verify the model, treatment plans were made for a homogeneous water phantom and a heterogeneous head phantom.
Results:
The planned doses agreed with the measurements within ±(plus or minus) 2% in both phantoms except for the doses at peripheral regions of the target with high dose gradient. To estimate the memory space and the computation time reduced with the proposed techniques, a treatment plan was made for a bone sarcoma case with a target volume of 1.94 litters. The memory space for the kernel and the computation time for the final dose calculation were reduced to 1/22 and 1/100 of the ones without the techniques, respectively.
Conclusion:
The computation with the model using the proposed techniques is fast, accurate and applicable to the dose optimization and the calculation in the treatment planning of scanned C-ion therapy.
Key Word(s): 1. Dose calculation algorithm; 2. Scanned carbon-ion therapy; 3. Beam model; 4. Scanned carbon-ion therapy;, 53rd Annual Conference of the Particle Therapy Co-Operative Group (PTCOG53)},
 title = {Improvement of the accuracy  and the speed of dose calculation in the treatment planning of scanned C-ion therapy},
 year = {2014}
}