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Yamashita, Shinichi; Taguchi, Mitsumasa; Baldacchino, G.*; Katsumura, Yosuke
Charged Particle and Photon Interactions with Matter; Recent Advances, Applications, and Interfaces, p.325 - 354, 2010/12
Irradiation effects induced by heavy ions are much different from those by low-LET radiations. Such distinctiveness has been applied to cancer therapy, surface processing, analytical techniques, and so on. However, detailed mechanism through which such distinctiveness appears has not been clarified yet. In this chapter, what have experimentally been found recently, especially within these five years, in water radiolysis with positively-charged atomic heavy ions are shown. Steady-state radiolysis studies and pulse radiolysis studies are separately summarized because these two approaches inherently involve own advantages and limitations. Gathering reported products yields and kinetics, track structures and intra-track dynamics are discussed. One of the most characteristic features of recent studies is that track-segment or -differential yields were intensively measured compared to earlier studies.
Lin, M.; Muroya, Yusa*; Baldacchino, G.*; Katsumura, Yosuke*
Recent Trends in Radiation Chemistry, p.255 - 277, 2010/05
In this review paper, we have summarized the important results obtained in the last decade concerning the radiation chemistry studies on high temperature and supercritical water, especially the radiolytic yields of water decomposition products, the reaction rate constants, and the spectral properties of transient species, etc. The importance of density effects under supercritical conditions is pointed out.
OH yields with fluorescent probe, 1; Investigation into reaction mechanism and reactivity toward water decomposition radicals of coumarin-3-carboxylic acidMaeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Muroya, Yusa*; Taguchi, Mitsumasa; Kimura, Atsushi; Katsumura, Yosuke
no journal, ,
no abstracts in English
Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Katsumura, Yosuke; Murakami, Takeshi*
no journal, ,
no abstracts in English
Yamashita, Shinichi; Maeyama, Takuya*; Baldacchino, G.*; Katsumura, Yosuke; Muroya, Yusa*; Taguchi, Mitsumasa; Kimura, Atsushi; Murakami, Takeshi*
no journal, ,
A novel sensitive method to determine OH yield in water radiolysis has been developed and has been applied for heavy-ion irradiations. In this work, this method was extended to measurement near the Bragg peak. It was found that OH yield has minimum value near the Bragg peak and is different even for the same ion irradiation of different acceleration energies.
Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Katsumura, Yosuke; Muroya, Yusa*; Taguchi, Mitsumasa; Kimura, Atsushi; Murakami, Takeshi*
no journal, ,
OH yield near the Bragg peak of high-energy heavy ions, of which energies are comparable to those used in cancer therapy, has been determined in the previous work. Because fragmentations of primary projectile are significant in the energy region, it was purposed to calculate the fragmentations with an existing code and to reproduce the already obtained experimental results for verification of the code as well as for estimation of how much each fragmentated ions contributes in terms of OH yield.
OH with therapeutic ion beamMaeyama, Takuya*; Katsumura, Yosuke; Yamashita, Shinichi; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Murakami, Takeshi*
no journal, ,
Solution of Coumarin-3-carboxylic acid (CCA) has been applied to yield measurement of OH in water radiolysis with carbon ion beams. Production yield of a fluorescent probe, 7OH-CCA, which is a stable product produced after scavenging reaction for OH by CCA, was determined by using HPLC connected to a fluorometer. By using this chemical system, OH yields near the Bragg peak have been measured. Contribution of fragmentations, which are known to be significant near the Bragg peak of high-energy heavy ions, is also discussed by conducting fragmentation simulation with deterministic, semi-empirical and one-dimensional code named HIBRAC.
OH yield near the Bragg peakMaeyama, Takuya*; Yamashita, Shinichi; Katsumura, Yosuke; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Midorikawa, Masamichi*; Funtowiez, D.*; Murakami, Takeshi*
no journal, ,
no abstracts in English
Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Katsumura, Yosuke; Taguchi, Mitsumasa; Kimura, Atsushi; Muroya, Yusa*; Murakami, Takeshi*
no journal, ,
Cancer therapy needs ions of several GeV to attain sufficiently long penetration depth into human body (normally 30 cm) to treat cancer in deep position. While advantages of heavy ion therapy are well-known phenomenologically, details of mechanism in which heavy ion irradiation leads to distinctive biological effectiveness have not been clarified yet. Then, understanding of water radiolysis with heavy ions is necessary because water is main component of human body. Aqueous solution of Coumarin-3-carboxylic acid (CCA) has been applied to yield-measurement of OH produced in water radiolysis with therapeutic carbon ion beam provided from HIMAC at NIRS. Production yield of a fluorescent probe, 7OH-CCA, which is a stable product produced after scavenging reaction for OH by CCA, was determined by using HPLC connected to a fluorometer. By using this chemical system, OH yields near the Bragg peak have been measured. Contribution of fragmentations, which are known to be significant near the Bragg peak of high-energy heavy ions, is also discussed by conducting fragmentation simulation.
Yamashita, Shinichi; Funtowiez, D.*; Maeyama, Takuya*; Midorikawa, Masamichi*; Oka, Toshitaka; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Kudo, Hisaaki*; Katsumura, Yosuke; et al.
no journal, ,
Product yields of water radiolysis are inevitably important in understanding detailed mechanism of indirect action of ionizing radiations. We have conducted yield measurement of main products such as hydrated electron, hydroxyl radical (OH) and hydrogen peroxide. We have also developed a sensitive method to determine OH yield with a fluorescent probe. In the method, aqueous solution of coumarin-3-carboxylic acid (CCA) is irradiated and OH is scavenged by CCA, resulting in production of fluorescent product 7OH-CCA. Applying this method, OH yield near the Bragg peak has been measured in this study because the Bragg peak is overlapped cancer position in actual therapy. Beams of C 290 and 135 MeV/u and so on were taken for irradiation at the biological irradiation port at HIMAC facility of NIRS. It was found that OH yield show minimal value around the Bragg peak for every ion beam and it drastically jumps up several times at just downstream of the Bragg peak. It is already well known that contributions of fragmentation particles become non-negligible for high-energy heavy ions. Thus, further consideration including fragmentations is necessary to separate contributions of different fragmentation particles. Such consideration is being attempted by using simulations with HIBRAC and PHITS.
Yamashita, Shinichi; Maeyama, Takuya*; Midorikawa, Masamichi*; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Kudo, Hisaaki*; Katsumura, Yosuke; Murakami, Takeshi*
no journal, ,
Recently, cancer therapy with high-energy heavy ions has been utilized, showing high efficiency in actual treatment. While its effectiveness has already been certificated phenomenologically, detailed mechanism through which such a feature appears has not been clarified yet. Water is a main component of human body, and then, it is inevitably important to comprehend water radiolysis. In this study, water radiolysis near the Bragg peak was focused on because the peak is overlapped to cancer in actual treatment, and yield of hydroxyl radical (OH) has been determined because OH is assumed as a species most responsible to indirect action. In addition, contribution of fragmentation reactions which is significant for high-energy heavy ions were discussed from the viewpoint of OH yield.
Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Taguchi, Mitsumasa; Kudo, Hisaaki*; Sihver, L.*; Murakami, Takeshi*; Katsumura, Yosuke
no journal, ,
Yield of hydroxyl radical (OH) has been measured near the Bragg peak of therapeutic heavy ions. Such a highly energetic heavy ions go through fragmentation reactions and its contribution has been quantitatively estimated with computer simulation. There are two kinds of simulation codes. One it deterministic 1D code, which needs only a few minutes for single calculation, and the other is stochastic 3D code, which can be extended to wide variety of beam configurations and more close to real situation. However, comparison of them has not been attempted intensively. In this study, measured OH yield has been reproduced by considering fragmentations based on these code and results were compared to extract advantages and disadvantages of them.
Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Taguchi, Mitsumasa; Kudo, Hisaaki*; Murakami, Takeshi*; Katsumura, Yosuke
no journal, ,
Yield of hydroxyl radical (OH), which is assumed to be most responsible species in indirect action, has been measured near the Bragg peak of therapeutic heavy ions. Such a highly energetic heavy ions go through fragmentation reactions, leading to production of lighter ions. Contribution of fragmentation to dose and so on increases near the Bragg peak. In this study, fragmentation reactions are simulated with PHITS code, which is developped by a group of JAEA. In the trial, the same irradiation system as used in actual experiment was taken into account, and each fragmentation ion was estimated quantitatively. In addition, measured OH yield was reproduced by using established knowledge.
Yamashita, Shinichi; Maeyama, Takuya*; Baldacchino, G.*; Muroya, Yusa*; Taguchi, Mitsumasa; Kimura, Atsushi; Louit, G.*; Katsumura, Yosuke; Murakami, Takeshi*
no journal, ,
no abstracts in English
Maeyama, Takuya*; Yamashita, Shinichi; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Muroya, Yusa*; Kudo, Hisaaki*; Oka, Toshitaka; Sato, Tatsuhiko; Katsumura, Yosuke; et al.
no journal, ,
no abstracts in English