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C and 
O nuclei by low-energy proton beamsAkagi, Takashi*; Yagi, Masashi*; Yamashita, Tomohiro*; Murakami, Masao*; Yamakawa, Yoshiyuki*; Kitamura, Keiji*; Ogura, Koichi; Kondo, Kiminori; Kawanishi, Shunichi*
Radiation Measurements, 59, p.262 - 269, 2013/12
Times Cited Count：16 Percentile：76.68(Nuclear Science & Technology)In proton therapy, positron emitters are induced from C andO nuclei by protons on the beam path in the patient. Many studies for monitoring positron emitters with beam-induced PET technique have been performed by various groups to verify the proton beam range and the dose in the patient for quality assurance. The aim of this study was to develop a method for measuring the production cross sections of positron emitters using standard equipment for proton therapy. The time-activity curve was then obtained with a high-sensitivity PET scanner to extract the number of positron emitters produced in the target. The production cross sections for four reaction channels: O(p,pn)
O, O(p,3p3n)
C, O(p,2p2n)
N, and C(p,pn)C were then measured. The cross sections for the O(p,pn)O reaction channel were consistent with data of previous experiments within the uncertainties, while those of C(p,pn)C were generally lower than data of previous experiments.
Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Mori, Michiaki; Teshima, Teruki*; Numasaki, Hodaka*; Murakami, Masao*; Demizu, Yusuke*; Akagi, Takashi*; Nagayama, Shinichi*; et al.
Applied Physics Letters, 94(18), p.181502_1 - 181502_3, 2009/05
Times Cited Count：110 Percentile：94.75(Physics, Applied)Murakami, Masao*; Demizu, Yusuke*; Niwa, Yasue*; Nagayama, Shinichi*; Maeda, Takuya*; Baba, Masashi*; Miyawaki, Daisuke*; Terashima, Kazuki*; Arimura, Takeshi*; Mima, Masayuki*; et al.
no journal, ,
Bolton, P.; Abe, Mitsuyuki*; Akagi, Takashi*; Nuesslin, F.*; Hori, Toshihiko; Iwashita, Yoshihisa*; Kawanishi, Shunichi; Kondo, Kiminori; Maeda, Takuya; Molls, M.*; et al.
no journal, ,
Bolton, P.; Iwase, Hiroshi*; Akagi, Takashi*; Murakami, Masao*
no journal, ,
Kanasaki, Masato; Sakaki, Hironao; Fukuda, Yuji; Yogo, Akifumi; Jinno, Satoshi; Kondo, Kiminori; Akagi, Takashi*; Hattori, Atsuto*; Matsukawa, Kenya*; Oda, Keiji*; et al.
no journal, ,
In the laser-driven ion acceleration experiment, fast electrons and X-rays also generated and these particles could cause significant contaminants to the ion detectors an a background noise. In the present study, to minimize the noise signals, we have optimized thickness of ZnS(Ag) fluorescent screen, which is much sensitive for ions, through Monte Carlo particle transport code PHITS. And we have also evaluate the response of the fluorescent screen as a function of fluence using rf-accelerator.
Kanasaki, Masato; Fukuda, Yuji; Sakaki, Hironao; Yogo, Akifumi; Jinno, Satoshi; Nishiuchi, Mamiko; Ogura, Koichi; Akagi, Takashi*; Kondo, Kiminori; Oda, Keiji*; et al.
no journal, ,
Recently, high energy protons with a maximum energy of 40 MeV have been generated by laser-driven ion acceleration experiment with solid target. Although, the CR-39 detectors have been widely utilized in the laser-driven ion acceleration experiments, it has not been carried out the precise analysis for each etch pit. In the present study, we have applied the multi-step etching technique to stacked CR-39 detector unit which is irradiated by laser-accelerated protons. This method allows us to measure the maximum energy of proton precisely, which can obtain high energy resolution with uncertainty 
E = 0.1 MeV. And also we have carried out the on-line measurement using ZnS(Ag) fluorescent screen for laser-accelerated ion beams.
Akagi, Takashi*; Yamashita, Tomohiro*; Uemoto, Kenji*; Sakaki, Hironao; Demizu, Yusuke*; Fuwa, Nobukazu*
no journal, ,
To develop a real-time two dimensional dosimetry with a scintillation screen. A multidimensional dosimetry system is needed for quality assurance of dose distributions in proton therapy, especially proton therapy with a pencil beam scanning system. An organic scintillation material is often used for the dosimetry systems due to the handleability; however organic scintillators have a poor linearity with respect to the linear energy transfer (LET). Meanwhile, inorganic scintillators have comparably good linearity to the LET; however they are difficult to handle. In this study we employ one of inorganic scintillators, silver- activated zinc sulfide, ZnS(Ag), as a scintillator because of the linearity to the LET.
