The image guided radio therapy (IGRT) Imaging System based on cone-beam computer tomography (CBCT) can reach the goal of improving the accuracy of the radiotherapy. However, because the clinical registration between CBCT images and Planning CT images is carried out manually, it inevitably reduces radiation positioning accuracy to some extent. To tackle the problem, we proposed a new feature vector selection method for the CBCT image elastic registration in the framework of hierarchical attribute matching mechanism for elastic registration (HAMMER) algorithm. We analyzed the characteristics of HAMMER algorithm and used Canny operator which has a better edge detection and positioning performance to replace the noise-sensitive gradient amplitude. Therefore, we used a new attribute vector, which consisted of the intensity, Laplacian of the Gaussian and Canny operator, to ex tract the image feature points in CBCT and planning CT images. We also presented an adaptive feature-point selection method and the choice criteria of attribute vector weights. Experimental results showed that the new feature vector effectively avoided the noise interference resulted from scattering lines in CBCT images to improve registration accuracy, and it also decreased the required feature point numbers and reduced the computation redundancy, so that it provided a new approach for the clinical elastic registration of CBCT and Planning CT rapidly and accurately.
Algorithms ; Cone-Beam Computed Tomography ; Humans ; Radiotherapy ; methods ; Radiotherapy Planning, Computer-Assisted

Nonalcoholic fatty liver disease (NAFLD) is the most important chronic liver disease in China, with increasing morbidity and mortality rates of extrahepatic diseases such as cardiovascular diseases and portal vein thrombosis (PVT). NAFLD complicated by PVT has a different mechanism from liver cirrhosis. Starting from grade Ⅲ coagulation disorder, this article elaborates on the pathogenesis of NAFLD complicated by PVT from three different grades and in steps and describes the new concept of sports and exercise in the prevention and treatment of NAFLD complicated by PVT, which brings a technical challenge for liver transplantation recipients with NAFLD complicated by PVT and is of great significance to improve the prognosis and quality of life of patients.

Nonalcoholic fatty liver disease (NAFLD) is characterized by the pathological feature of hepatocyte fatty degeneration and lipid accumulation, and liver histopathology evolves from simple liver fatty degeneration to steatohepatitis with hepatocellular injury and finally progresses to liver fibrosis, liver cirrhosis, and even liver cancer. NAFLD is closely associated with metabolic syndrome and colorectal tumors and can even lead to disability and death, and therefore, it is of great importance to diagnose nonalcoholic steatohepatitis (NASH) as early as possible and clarify liver fibrosis degree. As the gold standard for determining the liver histopathological grade and stage of NAFLD, liver biopsy has always been a main method for the diagnosis of liver fibrosis. However, the limitations of liver biopsy have greatly promoted the rapid development of noninvasive diagnostic techniques in recent years. The sensitivity and specificity of serology models and imaging tests in the diagnosis of NASH and early-stage liver fibrosis need to be improved. This article reviews the advances in noninvasive diagnostic methods for progressive NAFLD.