Coded Aperture X-ray Scatter Imaging
The ability to non-invasively image the molecular composition of an object is desirable in a number of application areas, such as medical imaging, security, structural integrity verification, and homeland defense. While x-ray imaging is the most effective strategy for tomographic imaging in such applications, conventional x-ray systems are not sensitive to molecular composition. Also, scanning x-ray systems capture only a small fraction of the radiation directed at the scanned object and are, therefore, highly inefficient. As a result, they require either x-ray sources capable of high power to increase the available radiation at the detector, or long exposure times. In either case, this exposes the scanned object to excessive amounts of x-ray radiation, which can be undesirable in many applications. There remains a need for an improved imaging system that noninvasively ascertains the structural and molecular composition of three-dimensional objects at high speed and with relatively lower cost and complexity.
Inventors at Duke University have developed a novel system for simultaneous imaging the structure and composition of object based on measurements of the low-angle x-ray diffraction properties of the object. This is achieved through the use of a coded aperture that encodes spatial and spectral features onto radiation scattered from image points within the object. In addition, multiple x-ray projections can be made simultaneously instead of sequentially as in conventional computed tomography (CT) systems. The coded aperture acts as a reference structure which disambiguates these superposed projections. By using decompressive inference, the number of images required for a 3D reconstruction is reduced. This approach enables snapshot operation, which opens possibilities for video-rate x-ray imaging.
Applications X-ray imaging systems for:
- Baggage scanning at security checkpoints to detect presence of threatening substance
- Diagnostics such as mammography to provide both an image and a chemical analysis of lesions and tumors
- Non-invasive testing of ceramic metals and composites
- Low cost
- High speed imaging
- Simpler system design
- Improved resolution
US Patent 9,335,281
David J. Brady
Michael J. Fitzpatrick Endowed Professor of Photonics
Professor of Electrical and Computer Engineering