Analysis Of Scatter And Radiation Dose In Triple-source X-ray Cone-beam CT Based On Monte Carlo Method

As an important medical imaging modality, X-ray Computed Tomography(CT) has been developed through a few generations since born in70's of20thcentury, and the development is still in progress. The emergence of Siemensdual-source CT in2005made the concept of multi-source CT geometry intoreality, and the triple-source CT, with even higher temporal resolution and imagequality than the dual-source, seems a promising mode for next generation of CTscanner. Scattering and radiation dose are two important indices to quantify theperformance of a CT scanner, which must be taken into consideration in thedevelopment of new CT system. Scattering will cause problems like offset ofHU value, artifacts and lower contrast, and all of them will affect the diagnosis.And the dose involves with radiation security issue, which is more and moresignificant nowadays. We developed a virtual triple-source CT system based onMonte Carlo simulation and researched the two issues in this dissertation. Themain contributions of this dissertation are as follows. We developed a CT simulation system SimProj based on the Monte Carloopen-source software EGSnrc, which can be easily used for designing CTsystem geometry on demand. We studied the relationship between cone-angle ofthe X-ray beam and the magnitude of scattered radiation, and analyzedscattering and its consequence in the reconstructed images. It has been foundthat, in the research of dose, the triple-source CT has the same level with theordinary single-source CT scanner, though three imaging subsystems areworking at the same time. The results of our work are helpful for thedevelopment of the triple-source CT and also laid the foundation for futuresimulation research.