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Distribution and Density of Hydroxyl Raidcal Generated by Heavy-Ion (Carbon) Beam Irradiation to Aqueous Sample
https://repo.qst.go.jp/records/70554
https://repo.qst.go.jp/records/7055426f9a9ca-251a-4945-a97c-659987d564e5
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2011-10-03 | |||||
| タイトル | ||||||
| タイトル | Distribution and Density of Hydroxyl Raidcal Generated by Heavy-Ion (Carbon) Beam Irradiation to Aqueous Sample | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_c94f | |||||
| 資源タイプ | conference object | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
Matsumoto, Kenichiro
× Matsumoto, Kenichiro× Nakanishi, Ikuo× 松本 謙一郎× 中西 郁夫 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | High linear energy transfer (LET) carbon ion beam cancer therapy is effective against hypoxic tumor because irradiation with high LET has a lower oxygen effect compare to low LET radiations. For improvement of carbon ion beam therapy, low fractionated protocols are planned to reduce mental pain of patients. When clinical dose become higher in future low fractionated protocols, however, generation of reactive oxygen species (ROS) by high LET beams will become un-negligible. Results in previous studies1,2 are suggesting that superoxide (O2-) and/or hydrogen peroxide (H2O2) may be an important species to regulate at lower LET part, which usually corresponds to a normal tissue at the carbon ion cancer therapy. Since O2- and H2O2 probably caused from dissolved oxygen in a sample, density of such ROS generated in the irradiated sample depends on the distribution of molecular oxygen. On the assumption that very first hydroxyl radical (OH) can be generated by radiolysis of water molecules, density of OH generated in the irradiated sample can depend on the distribution of water molecules. It may be presumed that generation of OH much denser and localized on the truck of radiations. In this study, distribution and density of OH caused in an aqueous gelatin sample irradiated by heavy-ion (carbon) beam was investigated. 100 mM Phosphate buffer including 0.05 mM DTPA was wormed up to 80DegC, and 3.5% gelatin was dissolved to the phosphate buffer. The gelatin solution was cooled down to room temperature and then DMPO was added in the gelatin solution with several concentrations (7.7--1650 mM). The reaction mixture was transferred to 50 mL Falcon T-25 flasks. The gelatin solution was caked at 2~4DegC. The caked gelatin samples in the flasks were kept in ice until irradiation. The gelatin samples were irradiated by 290 MeV carbon mono beam using HIMAC (Heavy-Ion Medical Accelerator in Chiba, National Institute of Radiological Sciences), applying several LET (20 to 180 keV/um) at the surface of the gelatin. The dose at the surface of the gelatin sample was 32 Gy. An aliquot (~35 uL) of gelatin from the irradiated side wall was sampled into a glass capillary immediately after irradiation. DMPO-OH (spin trapped OH) in the capillary samples were measured by X-band EPR spectrometer (JEOL). The experiments were repeated using X-ray for a comparison. X-ray irradiation was performed using PANTAK 320S (Shimazu). The reaction mixtures were irradiated with 32 Gy X-ray (Eeff = 80 keV) at a dose rate of 3.3 Gy/min. Amount of DMPO-OH generated by carbon-ion beam was markedly lower than that by X-ray. The EPR signal intensity of DMPO-OH in X-ray-irradiated sample was increased with concentration of DMPO added, then looks reached plateau around 30 mM DMPO. The concentration of DMPO-OH at the plateau level was around 30 uM. For carbon-ion beam, amount of DMPO-OH was lower than the case of X-ray irradiation, and it was decreased with increasing LET; however, the amount of DMPO-OH in carbon-beam-irradiated sample increased with DMPO concentration until 1650 mM of DMPO, and did not show plateau. The result suggests that OH generation around the truck of carbon ion beam was much dense compared with X-ray. |
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| 会議概要（会議名, 開催地, 会期, 主催者等） | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | SPIN 2011 (6th International Conference on Synthesis, Properties and Implications of Nitroxides) | |||||
| 発表年月日 | ||||||
| 日付 | 2011-09-29 | |||||
| 日付タイプ | Issued | |||||
