Grant: Discovery Grants Program - Individual

It is often desirable to make an assessment of location, motion and material properties of objects that are behind walls and other structures (that is, visually obscure).  Commonly used techniques include radiation, ultrasonic, microwave, magnetic/conductivity techniques and the like.  Ionizing radiation techniques are especially useful due to the penetrating nature of the source, and the ability to achieve reasonable resolution in a short period of time.  There are immediate requirements in diverse fields such as medical imaging, non-destructive investigation, customs inspection and security to perform rapid, high resolution inspection for properties of a hidden object that include shape, motion, and in some cases, potential threat.  For non-destructive testing, it can often be desirable to determine the motion of a material in, for example, a pipe buried within a structure.  For security applications, it is very desirable to determine if someone is hidden on the other side of a wall, the direction that person is moving, and whether that person is a threat to security personnel.  For medical applications, it is always desirable to obtain detailed (and perhaps single-sided) radiographs at lower radiation exposure (hence dose).  An especially difficult inspection mode is when there is only access from a single side of a object, as would be the case for determining something on the other side of a wall, without seeing it optically.  Since this is a low efficiency process, various techniques may be used to improve the possibility of obtaining real-time image information.  One technique that can be used is called coded-aperture imaging (a technique used by astrophysicists for imaging distant stars).  This research uses an x-ray coded aperture technique for one-sided investigation, since x-rays have the property of high penetration, while also being an "on/off" source (increased mobility and improved radiation safety considerations).  The algorithm development will also be equally applicable to other radiation sources.  New research into application of coded apertures to both source(s) and detector(s), including temporal dependence, will be investigated.