使用全因子方法最佳化TLD計讀儀以評估乳癌劑量

為了最佳化 Harshaw 3500 計讀儀之讀出系統，使用熱發光劑量計 TLD-100H加上全因子方法（full factorial design, FFD），設計出三個因子和兩個不同水準，產生8種不同之參數組合，以 ART 假體於 6 MV 之X光射線下評估乳癌治療劑量，本實驗之目的為設計與開發出改善計讀儀加熱溫度 (℃)、加熱速率 (℃/s)、及最高溫度 (℃)之最佳條件設計組，FFD建議使用八組帶有不同條件之分析組，於實際測量當中分析各組別之優值 (figure of merit, FOM)，越大越好。實驗結果得知，由原始設定組 FOM為 0.143，提升至 FFD推薦參數條件設定組 FOM為0.349，可以得到最佳之 TLD計讀儀參數條件，設定為初始溫度150 ℃、加熱速率9 ℃/s、最高溫度為240 ℃，共使用77個點用以監測乳房放射治療之劑量，最終，乳房之輻射劑量具顯著不同，於乳房附近未發現明顯之額外輻射劑量。

To optimize the readout system of Harshaw 3500 reader, the thermoluminescent dosimeter (TLD)-100H were applied via a 23 full factorial design (FFD) to evaluate the breast cancer dose coming from 6 MV X-ray of ART phantom.The purpose of this study is to design and develop an optimal setting of improving preheating temperature (℃), heating rate (℃/s), and the maximum temperature (℃)of TLD reader. Eight analyzed groups with different combination of levels were recommended, and analyzed via larger-the-better principle or figure of merit (FOM) in practical survey by FFD.Eventually, the FOM increased from 0.143 (original setting) to 0.349 of the optimization recommended by FFD. The suggested optimal factors were preheatinging at 150 ℃, with a heating rate of 9 ℃/s; and 240 ℃ of the maximum temperature for the reader. Accordingly, a total of 77 measurement points were utilized for breast monitoring. The breast was acquired significantly different radiation doses. The minimum detectable dose (MDD) was also discussed. No significant extra doses were detected near breast.