一种确定β-γ混合辐射场中β射线及γ射线剂量的方法

A method for radiation dose assessment ofβ-rays andγ-rays in mixedβ-γfields

目的为确定热释光剂量计在β-γ混合辐射场中β射线及γ射线剂量,提出了一种新的测量方法并对该方法进行验证,以探讨这种方法的有效性。方法将个人剂量监测用热释光剂量计分别置于β射线参考辐射场(^(90)Sr/^(90)Y,^(85)Kr)和γ射线参考辐射场(137Cs)中进行辐照。针对个人剂量当量Hp(10)和Hp(0.07),在2.0~15.0 mSv剂量范围内开展线性响应和归一至137Cs源的响应研究。通过个人剂量计中用于Hp(10)和Hp(0.07)监测处的探测器,确定混合辐射场中β射线和γ射线剂量,并对结果进行了验证。结果γ射线下Hp(10)和Hp(0.07)、β射线下Hp(0.07)的判定系数均满足R2>0.998。^(90)Sr/^(90)Y源和^(85)Kr源各剂量下归一至137Cs源的响应平均值,分别为1.14和0.18;通过剂量响应曲线得到的斜率值计算二者的归一至137Cs源的响应值分别为1.17和0.18。^(85)Kr源下,Hp(10)监测处的测得值与Hp(0.07)监测处的测得值之比(kR值)接近于0,137Cs源下的kR值接近于1。采用基于kR平均值与kR斜率值计算,得到的Hp(10)γ、Hp(0.07)γ和Hp(0.07)β的计算值与约定值最大相对偏差分别为6.1%与6.0%。结论该方法可应用于单个β源和单个γ源下β-γ混合辐射场的β射线及γ射线剂量评估。

Objective To test a new method with thermoluminescent dosimeters(TLDs)to determine theβ-ray andγ-ray doses ofβ-γmixed radiation fields.Methods TLDs for personal dose monitoring were irradiated in the reference radiation fields ofβ-rays(^(90)Sr/^(90)Y,^(85)Kr)andγ-rays(137Cs).Across the range of 2.0-15.0 mSv,the linearity of TLD response and normalized response with respect to 137Cs were determined at the depths of Hp(10)and Hp(0.07).Using TLD detector readings at the depths of Hp(10)and Hp(0.07),β-andγ-ray doses in the mixed radiation fields were determined,and the result were verified.Results For Hp(10)and Hp(0.07)underγ-ray exposure and Hp(0.07)underβ-ray exposure,the coefficient of determination(R2)were all>0.998.For the^(90)Sr/^(90)Y source and^(85)Kr source,the average values of response values normalized with respect to 137Cs at different doses were 1.14 and 0.18,respectively;and the normalized response values derived from the slope values of the dose-response curves for the two sources were 1.17 and 0.18,respectively.The ratios of measurements of Hp(10)to Hp(0.07),kR,for the^(85)Kr source were close to 0,while the kR values for the 137Cs source were close to 1.Using the average value of kR and the slope value of kR for calculation,the maximum relative deviations between the calculated values and conventional values for Hp(10)γ,Hp(0.07)γ,and Hp(0.07)βwere 6.1%and 6.0%,respectively.Conclusions This method can be applied for the assessment ofβ-ray andγ-ray doses inβ-γmixed radiation fields of a singleβsource and singleγsource.