Unidad de Medicina Experimental, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
Comput Methods Programs Biomed. 2012 Aug;107(2):218-32. doi: 10.1016/j.cmpb.2011.06.008. Epub 2011 Sep 9.
Most small-animal X-ray computed tomography (CT) scanners are based on cone-beam geometry with a flat-panel detector orbiting in a circular trajectory. Image reconstruction in these systems is usually performed by approximate methods based on the algorithm proposed by Feldkamp et al. (FDK). Besides the implementation of the reconstruction algorithm itself, in order to design a real system it is necessary to take into account numerous issues so as to obtain the best quality images from the acquired data. This work presents a comprehensive, novel software architecture for small-animal CT scanners based on cone-beam geometry with circular scanning trajectory. The proposed architecture covers all the steps from the system calibration to the volume reconstruction and conversion into Hounsfield units. It includes an efficient implementation of an FDK-based reconstruction algorithm that takes advantage of system symmetries and allows for parallel reconstruction using a multiprocessor computer. Strategies for calibration and artifact correction are discussed to justify the strategies adopted. New procedures for multi-bed misalignment, beam-hardening, and Housfield units calibration are proposed. Experiments with phantoms and real data showed the suitability of the proposed software architecture for an X-ray small animal CT based on cone-beam geometry.
大多数小动物 X 射线计算机断层扫描（CT）扫描仪基于锥形束几何形状，带有在圆形轨道上旋转的平板探测器。这些系统中的图像重建通常通过基于 Feldkamp 等人提出的算法的近似方法来完成（FDK）。除了重建算法本身的实现外，为了设计一个实际的系统，还需要考虑许多问题，以便从获得的数据中获得最佳质量的图像。这项工作提出了一种基于锥形束几何形状和圆形扫描轨迹的小动物 CT 扫描仪的全面、新颖的软件架构。所提出的架构涵盖了从系统校准到体积重建和转换为亨氏单位的所有步骤。它包括一种基于 FDK 的高效重建算法的实现，该算法利用了系统的对称性，并允许使用多处理器计算机进行并行重建。讨论了校准和伪影校正的策略，以证明所采用的策略的合理性。提出了用于多床位失准、束硬化和亨氏单位校准的新程序。使用幻影和真实数据的实验表明，所提出的软件架构适用于基于锥形束几何形状的 X 射线小动物 CT。
