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首页> 外文期刊>Medical Physics >Feldkamp-based cone-beam reconstruction for gantry-tilted helical multislice CT.
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Feldkamp-based cone-beam reconstruction for gantry-tilted helical multislice CT.

机译：基于Feldkamp的锥梁重建，用于龙门倾斜式螺旋多层CT。

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Depending on the clinical application, it is frequently necessary to tilt the gantry of an x-ray CT system with respect to the patient and couch. For single-slice fan-beam systems, tilting the gantry introduces no errors or artifacts. Most current systems, however, are helical multislice systems with up to 16 slices. The multislice helical reconstruction algorithms used to create CT images must be modified to account for tilting of the gantry. If they are not, the quality of reconstructed images will be poor with the presence of significant artifacts, such as smearing and double-imaging of anatomical structures. Current CT systems employ three primary types of reconstruction algorithms: helical fan-beam approximation, advanced single-slice rebinning, and Feldkamp-based algorithms. This paper presents a generalized helical cone-beam Feldkamp-based algorithm that is valid for both tilted and nontilted orientations of the gantry. Unlike some of the other algorithms, generalization of the Feldkamp algorithm to include gantry tilt is simple and straightforward with no significant increase in computational complexity. The effect of gantry tilt for helical Feldkamp reconstruction is to introduce a lateral shift in the isocenter of the reconstructed slice of interest, which is a function of the tilt, couch speed, and view angle. The lateral shift is easily calculated and incorporated into the helical Feldkamp backprojection algorithm. A tilt-generalized helical Feldkamp algorithm has been developed and incorporated into Aquilion 16-slice CT (Toshiba, Japan) scanners. This paper describes modifications necessary for the tilt generalization and its verification.
机译：根据临床应用，经常需要使X射线CT系统的机架相对于患者和卧榻倾斜。对于单层扇形光束系统，倾斜机架不会产生任何错误或伪影。然而，当前大多数系统是具有多达16个切片的螺旋多层系统。必须修改用于创建CT图像的多层螺旋重建算法，以解决龙门架的倾斜问题。如果不是这样，则在存在明显伪影（例如解剖结构的污迹和二次成像）的情况下，重建图像的质量将很差。当前的CT系统采用三种主要的重建算法：螺旋扇形光束近似，高级单片重组和基于Feldkamp的算法。本文提出了一种基于广义螺旋锥束Feldkamp的算法，该算法对龙门架的倾斜和非倾斜方向均有效。与其他一些算法不同，将Feldkamp算法包括机架倾斜的概化非常简单明了，并且计算复杂度没有明显增加。龙门架倾斜对螺旋Feldkamp重建的影响是在重建的目标切片的等角点引入横向偏移，这是倾斜度，床速度和视角的函数。横向位移很容易计算，并合并到螺旋Feldkamp反投影算法中。已经开发了一种倾斜通用的螺旋Feldkamp算法，并将其合并到Aquilion 16层CT（日本东芝）的扫描仪中。本文介绍了倾斜综合及其验证所需的修改。

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