- 學位論文
質子與強子治療蒙地卡羅模擬
Proton and Hadron Therapy Simulation Through Monte Carlo Methods
摘要
光子和電子刀等治療方式已經日漸普及化，但是在殲滅癌細胞時易於破壞健康組織，未達到醫療的期望和治療最終效果。因此本研究著重在運用質子束以及強子射束進行劑量模擬，預測射束的深度劑量從前段較低處，進而中段劑量急遽爬升至最高點，而後急遽下降的曲線特點，以達成殲滅癌細胞的同時又可以不影響健康組織的最終目的，而在射束高劑量區的深度位置分布與射束能量及能量準確性有關係，這在治療癌症上面而言可以善加利用於控制能量大小將劑量準確的投射在入射方向的腫瘤所在精確的位置，但同時不影響在周遭正常未受感染的細胞組織，因此對垂直入射的方向上的橫向劑量分布預測亦是主要考量。 此篇研究主要目的是建立一套治療模擬模型，以便模擬治療射束在人體之中的劑量和治療效果。在人類體內有百分之七、八十的比率為水，所以本篇論文採用透過建立一個水立方的模型來近似人體在治療射束治療之下推得的深度劑量曲線，分析並拿來與電子刀、光子治療和強子等等治療比對。在偵測方面，在質子束的入口處和水立方的內部各放置一個具有空間解析度為一毫米的條狀偵測器，分別作為監控和量測數值使用。首先，利用探測器得知該位置的質子束大小及形狀，再由水立方之中的探測器量測深度劑量曲線與蒙地卡羅模擬進行比對得知質子束的能量。再來，因為在實際情形之下，各種粒子皆有它的不同分布曲線狀況，所以經由蒙地卡羅的邏輯理論，將各種平均自由徑及分布狀態和粒子配對之後，模擬得知的結果綜合作圖，比對各種治療的利弊得失以及副作用。 最後得知，理想的質子射束治療可以減低組織前段以及後段的吸收劑量，達到預期的效能以及劑量集中化，電子刀以及光子刀則會劑量集中在前面區段，所以破壞程度稍大，但是當運用強子(或碳離子)射束治療同時，能量甚至集中度可以超越質子治療，唯一的缺點就是後段劑量隨深度的下降趨勢不夠明顯且容易造成副作用，但是整體影響不大，進而成為目前放射性治療的主要發展重點。
並列摘要
To date, photon radiation therapy and electron knife therapy are quite popular. However, there are still many side effects to the uninfected tissues. Therefore, through my thesis I am going to focus on the proton and hadron beam therapy, especially on the dose simulation. To achieve the goal of killing the infected tumor cells and also without influencing the surrounding normal tissues, we have to set up a mathematical model to predict the dose distribution along the beam path. The main objective of this thesis is to build up a radiation therapy model to simulate the beam therapy in human cells and to observe the dose effectiveness. It is known that the percentage of water in human cells is about seventy to eighty percent, it is reasonable to take human cells as a water phantom cubic model in the realistic situation. Later on, by applying different kinds of beamlines such as electron knife, photon radiation, and hadron and proton particles, we can compare the dosage distribution by distribution plot simulated through the Monte Carlo simulation package Geant4. In summary, the most ideal beamlines from the simulation results is the proton and/or hadron beam. Comparing with the electron and photon beams, the dosage of proton and hadron can be raised up to almost one hundred percent which minimizes the side effects of residual dosage on normal tissues. The main defects of the carbon beam for the hadron therapy is the fragmentation tail. However, the dose range and damage compared to the peak of the dosage is too tiny and can be ignored. The hadron therapy as well as the proton therapy are still the most effective treatment to kill the tumors nowadays.
參考文獻
延伸閱讀
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