Research And Implementation Of Three Dimensional Illumination Model For Mammary Gland Ultrasound Imaging

The three-dimensional ultrasound imaging of mammary gland,which is the most intuitive way to diagnose the breast tumor,has become a research hotspot.Lots of ultrasonic manufacturers and medical research institutions pay much attention on it.Compared with the traditional two-dimensional imaging,this new technology can display the internal structure of the entire breast and see any cutting section from any view angle within 360 degrees.Therefore,it can significantly improve the probability to find the breast cancer.The contribution of this thesis mainly includes:(1)The background and significance of the three-dimensional imaging of mammary gland are studied.The thesis introduces the research status of domestic and foreign ultrasonic manufacturers and medical research institutions in recent years.The five basic illumination models and classic Phong illumination model are analyzed.We focus on local ambient occlusion which is a recently proposed algorithm for modeling volumetric shadow effects.The performance of these models is verified and analyzed.(2)In this thesis,we present a volumetric lighting model,which simulates scattering as well as shadowing in order to generate high quality volume renderings.The lighting model incorporates scattering,shadowing and specular reflections.In addition,the shadow computation is decoupled from the scattering,which allows us to assign different transfer functions in different color channels.It also allows us to incorporate indirect lighting by blurring the incoming light within a user-specified cone centered about the incoming light direction and blur the outgoing light within a cone facing away from the viewing direction at the same time.This lighting model can assign the customized medical characteristics and significantly improve on the quality of volume rendered images.In this thesis,we present a volumetric lighting model,which simulates illumination physically based on the existing volumetric lighting model.The results of this thesis show that this lighting model is significantly improved when comparing with other illumination model on the quality of volume rendered images.As it can be seen,for most cases our technique results in higher frame rates than conventional illumination model.The research of this thesis has a positive effect on the research and application of 3D illumination model in other related fields.