- 學位論文
利用人員劑量佩章進行輻射防護量與作業量之差異比較
Comparison of the differences between radiation protection quantities and operational quantities assessed by personal dosimeters
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摘要
由ICRU定義輻射防護作業量，一般被認定其能提供對於輻射防護量一保守之評估。本實驗利用侖道假體與熱發光劑量系統的方法量測實際之有效劑量與眼球水晶體與皮膚之等價劑量，並以目前常用之人員劑量計，熱發光人員劑量計與光刺激發光人員劑量計評估之不同深度個人等效劑量，於四種不同的光子曝露場(80 kV，130 kV，6 MV，10 MV)中，與4種不同曝露幾何(AP，PA，LLAT，RLAT)下，其兩者讀值差異，並計算出其轉換系數。一般國際文獻以蒙地卡羅模擬方式進行兩者數值之比對，本研究將實驗結果進行修正後與國際文獻進行比較。結果顯示，目前常用之人員劑量計僅在AP曝露條件下之大部分情形下在有效劑量部分可提供一保守之估計，在PA與RLAT曝露角度下，因佩章受到器官或組織之屏蔽使其低估真實防護量。而側邊照射時人員劑量佩章的結構會影響其評估，此為模擬方式並未考量的誤差。
並列摘要
Personal dose equivalent, Hp(d) defined by the International Commission on Radiation Units and Measurements, were commonly regarded as conservative surrogates of effective dose and equivalent dose of lens and skin. The study checked the valid of the assumption by experiments. E, effective dose was measured with RANDO phantom and TL system according to ICRP Recommendations. Hp(d) were measured with two kinds of dosimetry badges, Harshaw TLD dosimeters and Landauer OSLD dosimeters. The conversion coefficients of E/Hp(d) and HT/ Hp(d) were calculated which concerned irradiation by different photon energies (80 kV to10 MV)and irradiation geometries(AP, PA, RLAT, LLAT). The variance of conversion coefficients with five dosimeter positions in front of the torso which the radiation workers often wear on were discussed. The study also compared the conversion coefficients in this experiment with the published data which were simulated by Monte Carlo N-Particle code. The result showed that Hp(d) underestimate the effective dose and equivalent dose of lens and skin in some photon energies, especially low energies and some unfavorable geometries. And this study shows that defect of LAT geometry in the published data which was simulated.
參考文獻
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