电磁场数值计算方法可用于检测颅内异物。使用的重建算法有拟牛顿法、Bulirsch-Stoer外推法、局部加速收敛法。这些算法对改善重建计算的精度起着至关重要的作用。最后,仿真计算说明算法是有效的。 Electromagnetic field numerical method can be used to detect intracranial foreign body. Reconstruction algorithms used are Quasi-Newton method, Bulirsch-Stoer extrapolation method, local acceleration convergence method. These algorithms play a crucial role in improving the accuracy of reconstruction calculations. Finally, the simulation shows that the algorithm is effective.