低輻射劑量下TLD-100H之較正與線性測試

The Calibration and Linearity Test of TLe-100H in Low-level Radiation Exposure

董尚倫(Shang-Lung Dong) ； 羅濟慶(Chi-Ching Lo) ； 葉砡秀(Yuh-Shue Yeh) ； 張國華(Kao-Hua Chang) ； 陳弘政(Hung-Cheng Chen) ； 李俊信(Jason J. S. Lee)

《放射治療與腫瘤學》 4卷3期 (1997/09) Pp. 215-221

https://doi.org/10.6316/TRO/199704(3)215

摘要

目的：在放射治療期間，鄰近治療部位之正常組織會接受較低劑量之散射，為了能準確地評佔鄰近組織的吸收劑量，必須事先對熱發光劑量計進行篩選、校正與線性測試。
材料與方法：本研究採用下TLD-100H來進行劑量偵測，並建立在輻射劑量小於1 cGy時，TLD-100H對低劑量之篩選與校正係數的求法。同時也求出其劑量反應曲線，以判定計讀電量與照射劑量之間的關係，最後再做不準度測試以驗證其誤差度。
結果與討論：由研究的篩選結果可知，本次使用的25顆TLD中，有5顆在預測劑量時，無法將誤差度控制在3%以內，因此將其刪除。由線性度測試可知，劑量在0到0.9cGy時，計讀電量與照射劑量之間為線性關係，且判定係數(R^2)為0.9999。
結論：TLD-100H 在低劑量時，有非常高之靈敏度，並且相當穩定，十分適合低劑量輻射偵測。最後，經過本研究的篩選與校正，TLD-100H即在預測劑量時，可將不準度控制在3％以內。

關鍵字

熱發光劑量計 ； 吸收劑量 ； 校正係數

並列摘要

Purpose: It is clinically necessary to evaluate scatter radiation dose to the adjacent normal organs in most radiation therapy procedures. One must perform the calibration and linearity test for TLD in advance so that the scattered dose can be accurately determined.
Material and Method: The TLD-100H is used for dose measurement in the study. A method for selection and calibration of TLD in low-level radiation exposure is proposed, and their dose response curves are also determined. To verify the linear relationship between collected charges and received doses, a blind test is also presented to ensure that the overall uncertainty is under 3% of error.
Result: Five out of 25 TLD-100H, failed to report their predict doses within 3% error rate and therefore were eliminated from the study. The test of TLDs verified that the linearity performance is satisfactory with determination coefficient of 0.9999 in the range of 0~0.9 cGy.
Conclusion: The TLD-100H is very stable and sensitive, and is especially useful in low-level radiation detection. If the TLD-100H us carefully selected and calibrated, then the overall error rate is controlled within 3%, which is applicable for clinical studies.

並列關鍵字

Thermoluminescence dosimeter ； Absorbed dose ； Calibration factor