The Simulation Design And Analysis Of PCCT Imaging System Based On GATE

The energy spectrum CT can be realized in different ways.In essence,all these ways are based on the different attenuation of objects in different energy X-ray.The existing energy spectrum CT based on dual source or single source can not get the attenuation data of several energy bins by one scanning.In recent years,a new X-ray energy resolution photon counting detector has been developed.This technology can distinguish the ordinary ray source from polychromatic X-ray energy spectrum by recording the energy of the X-ray photon.The energy spectrum CT technology based on photon counting detector technology,called PCCT,is one of the hot research directions now.However,the photon counting detector is expensive and limited by the hardware conditions,so it is necessary to start from the simulation research,building the PCCT system to do the simulation imaging studies.In order to obtain PCCT scanning data,this paper analyzes the components of PCCT on the GATE simulation platform,and finally designs a PCCT system.Firstly,we simulate the actual X-ray radiation mode,and establish a more accurate X-ray tube model,including the anode target,the intrinsic filter and additional additional filters in the paper.Secondly,two simulation phantoms are designed according to the imaging requirements.Thirdly,the setup parameters of the photon counting detector under the simulation platform are given.Finally the imaging size of the whole system is analyzed,and the PCCT system parameters based on the GATE platform are given.Based on the above PCCT imaging system,the scanning data are processed by MATLAB program to get the projection data under two energy bins.Then,by using base-material-decomposition method,we can get the mono-energy images,effective electron density images and relative atomic number images from the projection data.Based on these results,the effect of the PCCT imaging system on material identification is evaluated.At last,the optimal energy of PCCT in removal of common medical metal artifacts is studied by experiments.The results show that the mono energy images from PCCT can weaken the metal artifacts under certain energy,and the best single energy of eliminating artifacts for titanium alloy and medical stainless steel is 120keV.For the photon counting detector,the energy-threshold correction is needed.The X-ray energy spectrum generated by the tube is related to the energy threshold correction of the photon counting detector,and also related to the energy spectrum imaging reconstruction algorithm,on this condition,the work of measuring the energy spectrum of the X-ray tube is done as well.Aiming at the existing attenuation transmission method for X-ray tube,an improved attenuation transmission method based on double matter wedge model is proposed.Mainly from the model of mathematical expression,simulation experiment settings,data processing and the final results and analysis of these parts of the statement.Simulation results based on GATE simulation platform show that the algorithm can calculate the energy spectrum distribution of the tube more accurately.