Johansson B E, Bahar-Gogani J, Wickman G
Radiation Physics Department, Umeå University, Sweden.
Phys Med Biol. 1999 Sep;44(9):2161-70. doi: 10.1088/0031-9155/44/9/304.
The general collection efficiency in the dielectric liquids iso-octane (CaH18; 2-2-4 trimethylpentane) and tetramethylsilane (Si(CH3)4), used as sensitive media in a thimble liquid ionization chamber (LIC) with a liquid layer thickness of 1 mm, has been studied. Measurements were made for continuous radiation at varying dose rates using 140 keV photons from the decay of 99mTc for chamber polarizing voltages of 50, 100 and 500 V. The maximum dose rate in each measurement session was about 150 mGy min(-1). The experimental results were compared with theoretical general collection efficiencies calculated by the equation for the general collection efficiency in gases. The results show that the general collection efficiency in a thimble LIC for continuous radiation can be calculated with the equation for the general collection efficiency in gas ionization chambers, using the same chamber geometry correction factors and analogous characteristic ion recombination parameters for the dielectric liquids.
研究了在液层厚度为1mm的指形液体电离室（LIC）中用作灵敏介质的介电液体异辛烷（C₈H₁₈；2 - 2 - 4三甲基戊烷）和四甲基硅烷（Si(CH₃)₄）中的总体收集效率。使用来自⁹⁹ᵐTc衰变的140keV光子，在50、100和500V的电离室极化电压下，针对不同剂量率的连续辐射进行了测量。每次测量时段的最大剂量率约为150mGy min⁻¹。将实验结果与根据气体中总体收集效率方程计算出的理论总体收集效率进行了比较。结果表明，对于连续辐射，指形LIC中的总体收集效率可以使用气体电离室中总体收集效率的方程来计算，使用相同的电离室几何形状校正因子以及介电液体类似的特征离子复合参数。
