臺灣博碩士論文加值系統

光刺激發光劑量計(OSLD)因高靈敏度、可重複計讀等優點，近些年已普遍被使用在研究或臨床上的劑量量測，但有著能量依存性的缺點，對低能量之光子有較高劑量響應而造成劑量高估。本研究使用OSLD與熱發光劑量計(TLD)以100 kV、120 kV、6 MV三種光子能量，分別量測探討在不同深度下，照野內與照野外之劑量響應並計算無濾片及有濾片之OSLD劑量響應比值(ROSLD1/ROSLD2)，再搭配蒙地卡羅方法模擬不同能量下的比值結果，推得有效能量與相關之修正因子後進行修正，以減少劑量誤差。結果顯示，在高能量6 MV光子照射下，OSLD能量依存性較小，修正後OSLD與TLD之誤差約為-20.26 %~27.46 %，低能量100 kV、120 kV光子照射下，OSLD能量依存性明顯，經修正後與TLD之誤差約為-15.58 %~25.47 %，本研究所建立之修正方法能適度降低能量依存性所造成OSLD的劑量誤差。

Optically simulated luminescent dosimeters (OSLDs) have been commonly used in research or clinical dose measurements due to their high sensitivity and can be read out multiple times. However, they have energy dependence, and they exhibit an over-response to low energy photons to misestimate the dose.
This study used OSLDs and thermoluminescent dosimeters (TLDs) irradiating with three photon energy (100 kV, 120 kV,6 MV) to measure the doses at in-field and out-of-field locations in different depth. Moreover, we calculated the dose response ratio (ROSLD1/ROSLD2) from measurement and used Monte Carlo methods to simulate the ratio of with and without filters in different energies. Effective energy and the correction factor would be decided to reduce the error.
The results show that OSLD have less energy dependence in the 6 MV high-energy photon irradiation. The dose errors after the verification compared to TLD are ranged from -20.26 %~27.46 %. In the low-energy photon irradiation (100 kV and 120 kV), OSLD showed energy dependence seriously and the dose errors compared to TLD are range from 66.67 % to 175 % before modification and 15.58 % to 25.47 % after modification. In this study we established a method to reduce the dose errors of OSLD caused by the energy dependence, by means of the modification, errors due to energy dependence can be reduced effectively.

中文摘要 I
Abstract II
致謝 IV
目次 V
表目錄 VIII
圖目錄 IX
第1章 緒論 1
1.1 前言 1
1.2 OSLD與TLD能量依存性之比較 2
1.3 文獻回顧 3
1.4 研究目的 9
第2章 材料與方法 10
2.1 前言 10
2.2 OSLD特性 10
2.2.1 OSL原理 10
2.2.2 OSLD計讀與迴火 12
2.2.3 OSLD再現性與篩選 14
2.2.4 OSLD校正曲線 16
2.3 熱發光劑量計 18
2.3.1 TLD原理 18
2.3.2 TLD計讀與回火 18
2.3.3 TLD篩選與校正曲線 20
2.4 游離腔之校正 22
2.5 假體設計與濾片 24
2.6 蒙地卡羅模擬 26
2.6.1 OSLD模擬結構與設計 27
2.6.2 OSLD修正方法 29
2.6.3 TLD修正方法 30
2.7 實驗設計 31
2.7.1 6 MV光子照射 31
2.7.2 100 kV、120 kV光子照射 35
2.7.3 OSLD能量依存性修正方法之流程 37
第3章 結果與討論 38
3.1 蒙地卡羅模擬結果 38
3.1.1 OSLD模擬結果與修正因子推估 38
3.1.2 TLD模擬結果與修正因子推估 41
3.2 高能量光子實驗結果 43
3.2.1 不同條件下之劑量分布 43
3.2.2 OSLD、TLD與游離腔量測劑量之比較 46
3.2.3 TLD與OSLD之修正與誤差評估 49
3.3 低能量光子實驗結果 50
3.3.1 TLD與OSLD量測劑量之比較 50
3.3.2 TLD與OSLD之修正與誤差評估 52
3.3.3 不同條件下之劑量分布 54
第4章 結論 56
參考文獻 58
附錄一 照野5 × 5 cm2之修正結果 61
附錄二 照野10 × 10 cm2之修正結果 63
附錄三 照野20 × 20 cm2之修正結果 65
附錄四 100 kV、0.5 mAs之修正結果 67
附錄五 120 kV、6.4 mAs之修正結果 69

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