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研究生:詹文棟
研究生(外文):Wen-Tung Chan
論文名稱:低能量電子與液態水之互應作用及在奈米體積內之能量沈積
論文名稱(外文):Low-Energy Electron Interactions with Liquid Water and Energy Depositions in Nanometric Volumes
指導教授:董傳中董傳中引用關係
指導教授(外文):Chuan-Jong Tung
學位類別:碩士
校院名稱:國立清華大學
系所名稱:生醫工程與環境科學系
學門:工程學門
學類:生醫工程學類
論文種類:學術論文
論文出版年:2007
畢業學年度:95
語文別:中文
論文頁數:93
中文關鍵詞:標靶治療液態水DNA非彈性作用截面
外文關鍵詞:Targeted therapyLiquid waterDNAInelastic cross section
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近年來,標靶治療的研究正蓬勃發展。其中放射基因療法是將鄂惹發射體鍵結到DNA上,並利用鄂惹電子會在數個奈米的範圍內大量沈積能量的特性來產生DNA傷害,達到治療的目的。要了解鄂惹發射體鍵結到DNA上後,所會造成的生物效應,除了進行生物實驗外,也可以利用蒙地卡羅模擬的方式來評估。蒙地卡羅模擬程式主要包含四個部分:作用截面資料、計算程序、幾何、與結果分析方法,其中作用截面資料及計算程序的正確與否決定了模擬結果的可靠性。因此本研究先以理論方法來計算低能量電子和介質的作用情形,使用改良過的裘德模式來計算水和DNA價電帶對於入射電子的非彈性作用截面,並利用重建受總和規則限制的古典�Z體碰撞模式來計算各內層軌域的非彈性作用截面,將這些作用截面應用於本實驗室所發展的奈米劑量模擬程式-NMC。NMC能夠評估低能量電子在一較簡化的DNA模型中造成傷害的情形,此模型包含兩半徑為0.5 nm、高16 nm的圓柱作為DNA的兩股,在兩股中能量沈積大於17.6 eV的事件會經由直接作用產生單股斷裂,而在距離兩股表面0.5 nm的範圍內,若有能量沈積大於12.6 eV的事件發生,則會產生自由基,有0.13的機率會經由間接作用造成單股斷裂,若兩股的單股斷裂發生在10個鹼基對內,則會造成雙股斷裂。本研究改進NMC的計算程序與分析方法,使能更精確的模擬低能量電子造成DNA傷害的能力,也藉由改變射源位置及能量,試著評估出最有效的基因治療法。
The investigation of targeted therapy is extensively conducted in recent years. One popular topic of them is Anti-gene radiotherapy. Anti-gene radiotherapy uses the property of Auger electrons that will deposit abundant energy in the range of nanometer to achieve the purpose of cure. Besides biological experiment, Monte Carlo simulation can also be used to estimate the biological effect caused by binding Auger emitter to DNA strands. There are four major portions in a Monte Carlo simulation code: cross section data, algorithm, geometry, and analysis. The accuracy of cross section data and algorithm can be crucial to the reliability of the simulation results. In this research, interactions of low-energy electrons with medium were investigated by theoretical method. Extended Drude dielectric model and reconstruction of sum-rule-constrained Classical-binary-collision model were used to calculate the inelastic cross section of valence band and inner shells of liquid water and DNA, respectively. Apply these cross section data to a developed Monte Carlo code-NMC, which provides an estimate of the damage caused by low-energy electrons in a simplified DNA model. This model consisted of two parallel cylinders of 0.5 nm in diameter, 16 nm in height. Any energy deposition greater than 17.6 eV in the cylinder was assumed to cause a single strand break (ssb) by direct action. An energy deposition of 12.6 eV or greater within 0.5 nm of the cylinder surface was assumed to induce an OH radical which had a probability of 0.13 to produce a ssb by indirect action. When two ssbs occurred on opposite strands separated by 10 or fewer base pairs, a double strand break (dsd) was assumed. The algorithm and analysis of NMC were improved to simulate more accuracy. Source position and energy were changed to find out the most effective way of Anti-gene radiotherapy
摘 要 i
誌 謝 iii
目 錄 iv
圖目錄 vii
表目錄 x
第一章 序論 1
第二章 低能量電子與介質的作用截面的理論計算 3
2.1 低能量電子和介質的互應作用 3
2.2 彈性作用截面 3
2.3 非彈性作用截面 5
2.4 價電帶的非彈性作用截面 6
2.4.1 理論方法 6
2.4.1.1 介電函數 6
2.4.1.2 波恩近似法 9
2.4.1.3 交換效應 10
2.4.1.4 電子的反平均自由行程、射程和凝體的阻擋本領 11

2.4.2 結果驗證與比較 13
2.4.2.1 液態水 13
2.4.2.2 DNA 18

2.5 內層軌道的非彈性作用截面 22
2.5.1 理論方法 22
2.5.2廣義振動體強度 23
2.5.3 受總和規則限制的古典�Z體碰撞模式 26
2.5.4重建受總和規則限制的古典�Z體碰撞模式 27
2.5.5 內層軌道的游離作用截面 31
2.5.6 結果討論 32
2.6 液態水和DNA的結果比較 36
第三章 蒙地卡羅程式NMC的簡介與改良 38
3.1 NMC的簡介 38
3.1.1 模擬流程 38
3.1.2 幾何結構 39
3.2 NMC的修正與改進 42
3.2.1 非彈性作用截面 42
3.2.2 彈性作用截面 44
3.2.3 二次電子的貢獻 45
3.3 結果討論 46
3.3.1 非彈性作用截面 46
3.3.2 彈性作用截面 48
3.3.3 二次電子的貢獻 51
3.3.4 彈性碰撞的影響 53
3.3.5 射源擺放位置的影響 54
3.3.6 間接作用區大小的影響 57
第四章 游離輻射的生物效應 63
4.1 能量沈積與單股斷裂 65
4.2不同電子事件和相同電子事件 68
4.3 以距離決定雙股斷裂 77
第五章 結論與建議 80
參考文獻 82
1 Hsiu-Wen Hsieh, 'The study of DNA Nanodosimetry', Department of Atomic Science, Taiwan, 2005.
2 C.J. Tung and C.P. Wang, 'Multiple Scattering of Low-Energy Electrons in Aluminum', IEEE Transactions on Nuclear Science, Ns-30: 61983.
3 Ton-Lian Chou and Chuan-Jong Tung, 'Interactions of Low Electrons with Liquid Water', Natl. Sci. Counc. Monthly, ROC, 101982, 411-420.
4 D. Emfietzoglou, M. Moscovitch and A. Pathak, 'Modeling the energy and momentum dependent loss function of the valence shells of liquid water', Nucl. Instr. and Meth. in phys. Res. B, 2302005, 77-84.
5 M. Dingfelder and M. Inokuti, 'The Bethe surface of liquid water', Radiat Environ Biophys, 38: 2, Jul 1999, 93-96.
6 D. Emfietzoglou, 'Inelastic cross-sections for electron transport in liquid water: a comparison of dielectric models', Radiation Physics and Chemistry, 662003, 373-385.
7 Edward D. Palik, Handbook of Optical Constants of Solids II, 1991.
8 D.E. Watt., Quantities for dosimetry of ionizing radiations in liquid water 1996.
9 D. Emfietzoglou and M. Moscovitch, 'Inelastic collision characteristics of electrons in liquid water', Nucl. Instr. and Meth. in phys. Res. B, 1932002, 71-78.
10 T. Inagaki, R. N. Hamm and E. T. Arakawa, 'Optical and dielectric properties of DNA in the extreme ultraviolet', The Journal of Chemical Physics, 611974, 4246-4250.
11 Barry D. Michael and Peter O'Neill, 'A Sting in the Tail of Electron Tracks', SCIENCE, 2872000, 1603-1604.
12 Badia Bouda��¬ffa, Pierre Cloutier and Darel Hunting, 'Resonant Formation of DNA Strand Breaks by Low-Energy (3 to 20 eV) Electrons', SCIENCE, 2872000, 1658-1660.
13 Zhenyu Tan, Yueyuan Xia and Xiangdong Liu •, 'Cross sections of electron inelastic interactions in DNA', Radiat Environ Biophys, 432004, 173-182.
14 Simon M. Pimblott and Jay A. LaVerne, 'Energy loss by electrons in DNA'.
15 C. M. Kwei, Y. F. Chen and C.J. Tung, 'Reconstruction of the sum-rule-constrained classical binary-collision model for inner-shell ionizations', Physical Review A, 45: 71991, 4421-4425.
16 C.J. Tung, 'Sum-rule-constrained classical binary-collision model for inner-shell ionizations', Physical Review A, 22: 61980, 2550-2555.
17 Francesc Salvat and Aleksander Jablonski, 'ELSEPA–Dirac partial-wave calculation of elastic scattering of electrons and positrons by atoms, positive ions and molecules', 2004.
18 H. Nikjoo, P. O'Neill, M. Terrissol and D.T. Goodhead, 'Quantitative modelling of DNA damage using Monte Carlo track structure method', Radiat Environ Biophys, 381999, 31-38.
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