用电子顺磁共振波谱拟合方法估算牙釉质辐射剂量

目的 探讨运用电子顺磁共振(electron paramagnetic resonance, EPR)波谱拟合技术估算牙釉质EPR辐射剂量的准确性。方法 编制多成分叠加型EPR粉末波谱拟合软件,分别拟合牙齿本底信号(background signal,BS)和辐照诱发信号(radiation-induced signal,RS)的EPR波谱模型,用波谱模型叠加计算方法拟合出实际辐照后牙釉质的EPR波谱,从复合谱中提取出RS成分并计算其相对强度,建立剂量响应曲线,估算样品剂量,并将剂量估算结果与传统的波谱强度测量方法进行比较。结果 拟合获得的BS信号为单峰高斯线形粉末谱,g=2.0035,线宽Hpp=0.650-1.100 mT; RS信号为轴对称多晶粉末谱线形,其g_⊥=2.0018,g_‖＝1.9965,线宽Hpp=0.335-0.400 mT;分离BS与RS后得到的RS相对强度与辐照剂量呈线性相关,剂量响应方程为:y=240.74x+76 724(R²=0.9947),剂量估算结果相对误差期望值为0.13。结论 EPR波谱拟合方法在一定程度上提高了牙釉质辐射剂量估计的准确性和可信度。

Enamel dose calculation by electron paramagnetic resonance spectral simulation technique

Objective To optimize the enamel electron paramagnetic resonance (EPR) spectral processing by using the EPR spectral simulation method to improve the accuracy of enamel EPR dosimetry and reduce artificial error.Methods The multi-component superimposed EPR powder spectral simulation software was developed to simulate EPR spectrum models of the background signal(BS) and the radiation- induced signal (RS) of irradiated enamel respectively.RS was extracted from the multi-component superimposed spectrum of irradiated enamel and its amplitude was calculated.The dose-response curve was then established for calculating the doses of a group of enamel samples.The result of estimated dose was compared with that calculated by traditional method.Results BS was simulated as a powder spectrum of gaussian line shape with the following spectrum parameters:g =2.00 35 and Hpp =0.65 - 1.1 mT,RS signal was also simulated as a powder spectrum but with axi-symmetric spectrum characteristics.The spectrum parameters of RS were:g(1) =2.0018,g (11) =1.996 5,Hpp =0.335 - 0.4 mT.The amplitude of RS had a linear response to radiation dose with the regression equation as y =240.74x + 76 724 ( R2 =0.9947 ).The expectation of relative error of dose estimation was 0.13.Conclusions EPR simulation method has improved somehow the accuracy and reliability of enamel EPR dose estimation.