Hoffman John, Young Stefano, Noo Frédéric, McNitt-Gray Michael
Departments of Biomedical Physics and Radiology, David Geffen School of Medicine at UCLA, Los Angeles, California 90024.
Department of Radiology, David Geffen School of Medicine at UCLA, Los Angeles, California 90024.
Med Phys. 2016 Mar;43(3):1411-20. doi: 10.1118/1.4941953.
With growing interest in quantitative imaging, radiomics, and CAD using CT imaging, the need to explore the impacts of acquisition and reconstruction parameters has grown. This usually requires extensive access to the scanner on which the data were acquired and its workflow is not designed for large-scale reconstruction projects. Therefore, the authors have developed a freely available, open-source software package implementing a common reconstruction method, weighted filtered backprojection (wFBP), for helical fan-beam CT applications.
FreeCT_wFBP is a low-dependency, GPU-based reconstruction program utilizing c for the host code and Nvidia CUDA C for GPU code. The software is capable of reconstructing helical scans acquired with arbitrary pitch-values, and sampling techniques such as flying focal spots and a quarter-detector offset. In this work, the software has been described and evaluated for reconstruction speed, image quality, and accuracy. Speed was evaluated based on acquisitions of the ACR CT accreditation phantom under four different flying focal spot configurations. Image quality was assessed using the same phantom by evaluating CT number accuracy, uniformity, and contrast to noise ratio (CNR). Finally, reconstructed mass-attenuation coefficient accuracy was evaluated using a simulated scan of a FORBILD thorax phantom and comparing reconstructed values to the known phantom values.
The average reconstruction time evaluated under all flying focal spot configurations was found to be 17.4 ± 1.0 s for a 512 row × 512 column × 32 slice volume. Reconstructions of the ACR phantom were found to meet all CT Accreditation Program criteria including CT number, CNR, and uniformity tests. Finally, reconstructed mass-attenuation coefficient values of water within the FORBILD thorax phantom agreed with original phantom values to within 0.0001 mm(2)/g (0.01%).
FreeCT_wFBP is a fast, highly configurable reconstruction package for third-generation CT available under the GNU GPL. It shows good performance with both clinical and simulated data.
随着对使用CT成像进行定量成像、放射组学和计算机辅助检测的兴趣日益增长，探索采集和重建参数的影响的需求也在增加。这通常需要广泛使用采集数据的扫描仪，并且其工作流程并非为大规模重建项目设计。因此，作者开发了一个免费的开源软件包，用于螺旋扇形束CT应用，实现一种常见的重建方法，即加权滤波反投影（wFBP）。
FreeCT_wFBP是一个低依赖性、基于GPU的重建程序，主机代码使用C语言，GPU代码使用英伟达CUDA C语言。该软件能够重建以任意螺距值采集的螺旋扫描，以及诸如飞焦点和四分之一探测器偏移等采样技术。在这项工作中，对该软件进行了描述，并对其重建速度、图像质量和准确性进行了评估。基于在四种不同飞焦点配置下对ACR CT认证体模的采集来评估速度。通过评估CT值准确性、均匀性和对比度噪声比（CNR），使用相同的体模评估图像质量。最后，使用FORBILD胸部体模的模拟扫描评估重建的质量衰减系数准确性，并将重建值与已知的体模值进行比较。
对于512行×512列×32层的容积，在所有飞焦点配置下评估的平均重建时间为17.4±1.0秒。发现ACR体模的重建符合所有CT认证计划标准，包括CT值、CNR和均匀性测试。最后，FORBILD胸部体模内水的重建质量衰减系数值与原始体模值的一致性在0.0001 mm(2)/g（0.01%）以内。
FreeCT_wFBP是一个可根据GNU GPL获得的用于第三代CT的快速、高度可配置的重建软件包。它在临床和模拟数据方面均表现出良好的性能。
