Aortic stent has been widely used in restoring vascular stenosis and assisting patients with cardiovascular disease. The effective visualization of aortic stent is considered to be critical to ensure the effectiveness and functions of the aortic stent in clinical practice. Volume rendering with ray casting has been used as an effective approach to enable the effective visualization of aortic stent. The volume rendering relies on the transfer function that converts the medical images into optical attributes including color and transparency. This article proposes a new transfer function, namely, the multi-dimensional transfer function, to provide additional transparency value of a voxel. The proposed approach using the additional transparency value effectively assists the distinguishing of tissues that have the same CT value. The transparency values are simultaneously determined by gray threshold and gray change threshold, which can recognize the unnecessary structures such as bones transparent. A series of experimental results demonstrate that the situation of aorta stent of a patient can be directly observed, and the angle of view can be switched arbitrarily. The proposed method provides a new way for the operation of a virtual endoscopy to reach the place of blood vessels that a traditional endoscopy fails to reach.

中文翻译：

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一种新的主​​动脉支架容积可视化传递函数及其在虚拟内窥镜中的应用

主动脉支架已广泛用于修复血管狭窄和帮助心血管疾病患者。主动脉支架的有效可视化被认为是确保主动脉支架在临床实践中的有效性和功能的关键。具有射线投射的体绘制已被用作实现主动脉支架有效可视化的有效方法。体绘制依赖于将医学图像转换为包括颜色和透明度在内的光学属性的传递函数。本文提出了一种新的传递函数，即多维传递函数，以提供体素的附加透明度值。所提出的使用附加透明度值的方法有效地帮助区分具有相同 CT 值的组织。透明度值由灰度阈值和灰度变化阈值同时确定，可以识别骨骼透明等不必要的结构。一系列实验结果表明，可以直接观察患者主动脉支架的情况，并且可以任意切换视角。所提出的方法为虚拟内窥镜的操作提供了一种新的方法，可以到达传统内窥镜无法到达的血管位置。