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□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

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