用MCNP4B模拟X线成像过程

Monte Carlo simulation for X-ray imaging

蒙特卡罗方法是非常著名的模拟粒子输送问题的方法 ,它已经应用到医学放射诊断的图像分析和课题研究 ,但是除了人别情况外 ,蒙特卡罗方法很少同时应用于图像和剂量研究。本研究采用了蒙特卡罗方法的计算程序MCNP4B ,它可以模拟X线 /病人 /图像整个过程 ,并且其中任一参数的改变对图像和剂量的影响可以同时进行调查。在过去的一些研究中 ,通常采用均匀的模型来代替病人进行研究 ,本研究采用了数字虚拟人NORMAN ,这样能大提高模拟的精度。用MCNP4B模拟出的一些图像表明这套模拟方法对放射诊断研究是非常有帮助的。

Monte Carlo simulation is a well-known method for modelling radiation fields. It has been applied to diagnostic radiology for image analysis and for patient radiation dosimetry, but except for quite limited applications, not for both of these at the same time.In our research, a Monte Carlo code MCNP4B has been used. It allows the X-ray beam/patient/image receptor system to be modelled, so that various parameters can be varied allowing the simultaneous effect of these changes on both image quality and patient dose to be investigated. Many of these simulations were estimated by assuming a homogeneous phantom representing the patient. This restrictive assumption can be realised by a voxel phantom known as NORMAN, in order to improve the precision of the estimation. Some images obtained from the results of MCNP4B show that this simulation model is a helpful tool for diagnostic radiology.