Faragó Tomáš, Mikulík Petr, Ershov Alexey, Vogelgesang Matthias, Hänschke Daniel, Baumbach Tilo
Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology (KIT), Herrmann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
Department of Condensed Matter Physics, Faculty of Science, Masaryk University (MU), Kotlářská 2, 611 37 Brno, Czech Republic.
J Synchrotron Radiat. 2017 Nov 1;24(Pt 6):1283-1295. doi: 10.1107/S1600577517012255. Epub 2017 Oct 9.
An open-source framework for conducting a broad range of virtual X-ray imaging experiments, syris, is presented. The simulated wavefield created by a source propagates through an arbitrary number of objects until it reaches a detector. The objects in the light path and the source are time-dependent, which enables simulations of dynamic experiments, e.g. four-dimensional time-resolved tomography and laminography. The high-level interface of syris is written in Python and its modularity makes the framework very flexible. The computationally demanding parts behind this interface are implemented in OpenCL, which enables fast calculations on modern graphics processing units. The combination of flexibility and speed opens new possibilities for studying novel imaging methods and systematic search of optimal combinations of measurement conditions and data processing parameters. This can help to increase the success rates and efficiency of valuable synchrotron beam time. To demonstrate the capabilities of the framework, various experiments have been simulated and compared with real data. To show the use case of measurement and data processing parameter optimization based on simulation, a virtual counterpart of a high-speed radiography experiment was created and the simulated data were used to select a suitable motion estimation algorithm; one of its parameters was optimized in order to achieve the best motion estimation accuracy when applied on the real data. syris was also used to simulate tomographic data sets under various imaging conditions which impact the tomographic reconstruction accuracy, and it is shown how the accuracy may guide the selection of imaging conditions for particular use cases.
本文介绍了一个用于进行广泛虚拟X射线成像实验的开源框架syris。由源产生的模拟波场穿过任意数量的物体，直到到达探测器。光路中的物体和源都是随时间变化的，这使得能够模拟动态实验，例如四维时间分辨断层扫描和分层摄影。syris的高级接口用Python编写，其模块化使该框架非常灵活。此接口背后计算要求较高的部分在OpenCL中实现，这使得能够在现代图形处理单元上进行快速计算。灵活性和速度的结合为研究新型成像方法以及系统搜索测量条件和数据处理参数的最佳组合开辟了新的可能性。这有助于提高宝贵的同步加速器束流时间的成功率和效率。为了展示该框架的能力，已经模拟了各种实验并与实际数据进行了比较。为了展示基于模拟的测量和数据处理参数优化的用例，创建了高速射线照相实验的虚拟对应物，并使用模拟数据选择合适的运动估计算法；对其一个参数进行了优化，以便在应用于实际数据时实现最佳运动估计精度。syris还用于模拟在各种影响断层重建精度的成像条件下的断层数据集，并展示了精度如何指导针对特定用例的成像条件选择。
