@article{oai:repo.qst.go.jp:00078030,
 author = {Matsumoto, Shinnosuke and Yonai, Shunsuke and E Bolch, Wesley and Shinnosuke, Matsumoto and Shunsuke, Yonai},
 issue = {12},
 journal = {Medical physics},
 month = {Dec},
 note = {PURPOSE: To estimate out-of-field doses during carbon-ion radiotherapy (CIRT) for pediatric cerebellar ependymoma.
METHODS: Given that the out-of-field dose of CIRT depends on beam parameters, we set them for treatment of typical pediatric cerebellar ependymoma based on a previous study. The out-of-field dose during CIRT for pediatric cerebellar ependymoma was then estimated using the Particle and Heavy-Ion Transport code System with Monte Carlo simulations and a computational phantom developed at the University of Florida. From the simulation results, out-of-field doses at dose equivalents of passive beam and active scanning beam CIRT were calculated and compared to the secondary neutron-equivalent dose of passive beam CIRT and proton therapy.
RESULTS: The out-of-field dose equivalent decreases from 1.45 mSv/Gy (relative biological effectiveness - RBE) at the thyroid to 0.06 mSv/Gy (RBE) at the bladder, verifying decay as the distance from the treatment target increases. The out-of-field neutron-equivalent dose in organs per prescribed dose for passive beam CIRT is lower than that for passive beam proton therapy. Moreover, the out-of-field organ dose equivalent per prescribed dose for the active scanning beam CIRT is lower than that for the passive beam CIRT.
CONCLUSIONS: Active scanning beam CIRT is promising for pediatric cerebellar ependymoma regarding out-of-field exposure, outperforming the comparison radiotherapy modalities.},
 pages = {5824--5832},
 title = {Monte Carlo study of out-of-field exposure in carbon-ion radiotherapy: Organ doses in pediatric brain tumor treatment.},
 volume = {46},
 year = {2019}
}