对辐照牙釉质EPR谱数学模拟的研究

Mathematical simulation of irradiated tooth enamel EPR spectrum

目的 建立辐照牙釉质EPR谱数学模拟方法。方法 采用高斯函数一阶微商作为基本的模型函数 ,编写基于Marquardt Levenberg非线性最小二乘法曲线拟合算法的计算程序模拟辐照牙釉质EPR谱 ,并检验拟合精度。结果 对 2 70和 84 0mGy辐照的牙釉质样品的EPR复合谱 ,拟合后的残谱分别为 - 1 6 1± 2 3 5 9和 - 3 77± 2 4 94 ,残谱均值和标准差分别占各自峰高的 0 3%、3 8%和 0 4 %、3%。结论 这种算法和模型函数能很好地模拟辐照牙釉质EPR复合谱。

Objective To develop a method to sumulate mathematically the irradiated enamel EPR spectrum. Methods A first derivative Gaussian function was used as a basic function.A computer code was developed for spectrum simulation and processing using the nonlinear least square curve fit algorithm(the Newton's method with the MarquardtLevenberg modification)and was used to simulate the EPR spectrum of the irradiated tooth enamel.The simulation precision was also investigated. Results Simulation was done only in the signal possessing region.The average value and standard deviation of the residual spectrum of the 270 mGyirradiated enamel EPR spectrum were -1.61 and 23.59,respectively,which were about 0.3% and 3.8% of the peak value of its EPR spectrum,and were -3.77,24.94 and 0.4%,3% for the other 840 mGyirradiated enamel. Conclusion An accurate sumulation result can be gotten by using the algorithm and the obtained model function.;