Manerikar Ankit, Li Fangda, Kak Avinash C
School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA.
J Xray Sci Technol. 2021;29(2):259-285. doi: 10.3233/XST-200808.
Materials characterization made possible by dual energy CT (DECT) scanners is expected to considerably improve automatic detection of hazardous objects in checked and carry-on luggage at our airports. Training a computer to identify the hazardous items from DECT scans however implies training on a baggage dataset that can represent all the possible ways a threat item can packed inside a bag. Practically, however, generating such data is made challenging by the logistics (and the permissions) related to the handling of the hazardous materials.
The objective of this study is to present a software simulation pipeline that eliminates the need for a human to handle dangerous materials and that allows for virtually unlimited variability in the placement of such materials in a bag alongside benign materials.
In this paper, we present our DEBISim software pipeline that carries out an end-to-end simulation of a DECT scanner for virtual bags. The key highlights of DEBISim are: (i) A 3D user-interactive graphics editor for constructing a virtual 3D bag with manual placement of different types of objects in it; (ii) An automated virtual bag generation algorithm for creating randomized baggage datasets; (iii) An ability to spawn deformable sheets and liquid-filled containers in a virtual bag to represent plasticized and liquid explosives; and (iv) A GPU-based X-ray forward modelling block for spiral cone-beam scanners used in checked baggage screening.
We have tested our simulator using two standard CT phantoms: the American College of Radiology (ACR) phantom and the NIST security screening phantom as well as on a set of reference materials representing commonly encountered items in checked baggage. For these phantoms, we have assessed the quality of the simulator by comparing the simulated data reconstructions with real CT scans of the same phantoms. The comparison shows that the material-specific properties as well as the CT artifacts in the scans generated by DEBISim are close to those produced by an actual scanner.
DEBISim is an end-to-end simulation framework for rapidly generating X-ray baggage data for dual energy cone-beam scanners.
双能CT（DECT）扫描仪实现的材料表征有望显著改进对机场托运行李和随身携带行李中危险物品的自动检测。然而，训练计算机从DECT扫描中识别危险物品意味着要在一个行李数据集上进行训练，该数据集要能代表威胁物品在行李中所有可能的包装方式。然而实际上，由于与危险材料处理相关的后勤工作（以及许可），生成这样的数据具有挑战性。
本研究的目的是提出一种软件模拟流程，该流程无需人工处理危险材料，并允许在与良性材料一起放置在行李中的此类材料的放置方式上实现几乎无限的变化。
在本文中，我们展示了我们的DEBISim软件流程，该流程对虚拟行李进行DECT扫描仪的端到端模拟。DEBISim的关键亮点包括：（i）一个3D用户交互式图形编辑器，用于构建一个虚拟3D行李，并手动在其中放置不同类型的物体；（ii）一种自动虚拟行李生成算法，用于创建随机的行李数据集；（iii）能够在虚拟行李中生成可变形薄片和液体填充容器，以代表塑性炸药和液体炸药；（iv）一个基于GPU的X射线正向建模模块，用于托运行李筛查中使用的螺旋锥束扫描仪。
我们使用两种标准CT体模测试了我们的模拟器：美国放射学会（ACR）体模和美国国家标准与技术研究院（NIST）安全筛查体模，以及一组代表托运行李中常见物品的参考材料。对于这些体模，我们通过将模拟数据重建与相同体模的真实CT扫描进行比较，评估了模拟器的质量。比较结果表明，DEBISim生成的扫描中的材料特定属性以及CT伪影与实际扫描仪产生的属性接近。
DEBISim是一个端到端模拟框架，用于快速生成双能锥束扫描仪的X射线行李数据。
