摘要
磷光增感屏的内禀性质对磷光增感屏的成像性能影响很大.基于米氏(Mie)散射理论,计算得到磷光增感屏在不同颗粒尺寸和不同颗粒堆积密度情况下的散射系数和吸收系数.然后利用Monte Carlo(MC)方法模拟了可见光光子在磷光增感屏Gd2O2S:Tb(GOS)内的散射和吸收事件,得到磷光增感屏内不同位置处的可见光收集效率.利用MCNP程序模拟X射线束在磷光增感屏内的能量沉积分布,得到了金属-磷光增感屏总的点扩展函数(PSF).结果表明,在兆伏X射线成像系统中,使用小颗粒尺寸和高堆积密度的GOS磷光屏,可以改善增感屏系统的空间分辨率.
Light absorption and scatteing coefficients of phosphor grain with different sizes and packing densities are computed with Mie theory.Optical photons in a granular phosphor screen are modeled by simulating scattering and absorption events of individual optical photons by Monte Carlo method（MC）.Depth-dependent optical collection efficiencies are obtained.Using MCNP,distribution of energy deposition of 6 MeV mono-energetic X-ray in tungsten and phosphor screen is modeled.The point spread function of screen is given as a convolution of energy deposition kernel and optical kernel.Granular screens of smaller grain and higher packing density exhibit better spatial resolution in megavoltage radiography.
出处
《计算物理》
EI
CSCD
北大核心
2010年第6期816-822,共7页
Chinese Journal of Computational Physics
基金
国家自然科学基金委员会与中国工程物理研究院联合基金(10576006)
中国工程物理研究院科学技术发展基金(编号2009B0202020和2007A01001)资助项目
关键词
粒状磷光屏
米氏理论
点扩展函数
空间分辨率
granular phosphor screens
Mie theory
point spread function
resolution
