Simulation X-ray Spectrum And Dual-energy Peak Model,

X-ray computed tomography (CT) is a relative new technique developed in the late 1970's, which enables the nondestructive visualization of the internal structure of objects. CT is a widely used technique, with special emphasis on industrial and medical ap applications.Images reconstructed from polychromatic X-ray contain the "rings and cup" artifacts which seriously affect the quality of the CT images. When the X-ray traversing the object consists of X-rays with a spectrum of different energies, the lower X-ray energies will be absorbed more serious than the higher X-ray energies. So the beam becomes harder, which explains why this is called beam hardening. Hence, for polychromatic radiation the attenuation of a given material is not strictly proportional to its thickness. The reconstruction produces some visual distortions, such as pronounced edges and streak artifacts. The research of beam-hardening correction is of great meaning. X-ray spectrum play an important role in beam-hardening correction.This paper set up virtual X-ray source and research the influence of some factors affect the X-ray spectrum. We use GEANT4 to simulate X-ray source, including vacuum tub, filter, cathode, anode and so on. Then, we analyze how the target, filter, potential and current affect X-ray spectrum. Then we changed the inner structure of the virtual X-ray source and got the spectrum which X-ray intensity is more dense. In the end the paper gave a application of spectrum which have mentioned above.Elke Van de Casteele [5] presented a new beam-hardening correction method. The advantage of this method is the possibility to obtain more information about the X-ray spectrum through the physical parameters of the model. This model is called the bimodal energy model which is based on a physical background. The proposed model proves to give a good description of the beam hardening artifact for materials at specified X-ray spectrum. Furthermore a correction scheme is presented which gives good results for Iron. In the same time, we found the limitation of the bimodal energy model.