Krebs J, Shankar A, Bednarek D R, Rudin S
Toshiba (Canon) Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY.
Proc SPIE Int Soc Opt Eng. 2018 Feb;10573. doi: 10.1117/12.2293580. Epub 2018 Mar 9.
As neuro-endovascular image-guided interventions (EIGIs) make use of higher resolution detectors, gantry rotational motion-induced blur becomes more noticeable in acquired projections as well as reconstructed images by reducing the visibility of vascular and device features whose visualization could be critical in the treatment of vascular pathology. Motion-induced blur in projections views is a function of an object's position in the field-of-view (FOV), gantry rotational speed, and frame capture or exposure time. In this work different frame rates were used to investigate the effects of blurring from individual projections on the reconstructed image. To test the effects of these parameters on reconstructed images, a regular pattern phantom of small objects was simulated and projection views were generated at various different frame rates for a given simulated rotational velocity. The reconstruction was made using a linear interpolation of filtered backprojections. Images reconstructed from lower frame rates showed significant blurring in the azimuthal direction, increasingly worse towards the periphery of the image. However, those reconstructed from higher frame rates showed significantly less blur throughout the entire FOV. While lower frame rates could be used with slower gantry speeds this would increase the risk of voluntary or involuntary patient motion contributing to blur over the entire FOV. A high frame rate used with high gantry speeds could reliable provide images without gantry-motion blur while reducing the risk of patient-motion blur. Frame rates exceeding 2000 fps available with photon counting detectors such as the X-counter Actaeon are available.
由于神经血管内图像引导介入手术（EIGIs）使用了更高分辨率的探测器，在采集的投影图像以及重建图像中，机架旋转运动引起的模糊变得更加明显，这会降低血管和器械特征的可见性，而这些特征的可视化在血管病变治疗中可能至关重要。投影视图中的运动模糊是物体在视野（FOV）中的位置、机架旋转速度以及帧捕获或曝光时间的函数。在这项工作中，使用了不同的帧率来研究单个投影的模糊对重建图像的影响。为了测试这些参数对重建图像的影响，模拟了一个小物体的规则图案体模，并在给定的模拟旋转速度下以各种不同的帧率生成投影视图。使用滤波反投影的线性插值进行重建。从较低帧率重建的图像在方位方向上显示出明显的模糊，越靠近图像边缘越严重。然而，从较高帧率重建的图像在整个视野中显示出明显较少的模糊。虽然较低的帧率可以与较慢的机架速度配合使用，但这会增加患者自愿或非自愿运动导致整个视野模糊的风险。高帧率与高机架速度配合使用可以可靠地提供无机架运动模糊的图像，同时降低患者运动模糊的风险。像X-counter Actaeon这样的光子计数探测器可以提供超过2000帧/秒的帧率。
