减小电子涨落的指向概率虚拟源方法

为了减小X射线辐射照相蒙特卡罗模拟中成像平面上电子结果的涨落，尝试了一种新指向概率虚拟源方法。该方法利用指向概率法产生成像平面电子的主要来源虚拟X射线源，不仅在一次历史中增加了模拟电子的概率，而且使一次模拟对更多的记录点有贡献。使用指向概率虚拟源方法模拟结果表明:在X射线辐射照相中，指向概率虚拟源方法有效地减小了电子贡献的涨落，改善了模拟结果，提高了MCNP模拟X射线辐射照相过程的能力。

Method for creating virtual X-ray source with pointing probability method to decrease electron fluctuation

In order to decrease the fluctuation of electron’s record at imaging plane in MCNP’s simulation of X-ray radiography, a new method was tried for creating virtual X-ray source with pointing probability method. The virtual X-ray source may generate the next main electrons which has contribution to the detector. This method can not only increase the possibility of the electron, but also make a history contribute pixels as much as possible. The comparision of the results whether using the proposed method or not was carried out. The results show that the using of the method could decrease the fluctuation of the electron’s contribution effectively, improve the presion of the result, and develop the simulation capability of MCNP for X-ray radiography.