Walter Vincent Dixon

GE intelligent personal radiation locator system

The GE Intelligent Personal Radiation Locator (IPRL) system consists of multiple hand held radiation detectors and a base station. Each mobile unit has a CZT Compton camera radiation detector and can identify isotopes and determine the direction from which the radiation is detected. Using GPS and internal orientation sensors, the system continuously transforms all directional data into real-world coordinates. Detected radiation is wirelessly transmitted to the base station for system-wide analysis and situational awareness. Data can also be exchanged wirelessly between peers to enhance the overall detection efficiency of the system. The key design features and performance characteristics of the GE IPRL system are described.

Computer vision aided target linked radiation imaging

In this paper, we demonstrated an application of video tracking to radiation detection, where a vision-based tracking system enables a traditional CZT (cadmium zinc telluride)-based radiation imaging device to detect radioactive targets that are in motion. An integrated real-time system consisting of multiple fixed cameras and radiation detectors was implemented and tested. The multi-camera tracking system combines multiple feature cues (such as silhouette, appearance, and geometry) from different viewing angles to ensure consistent target identities under challenging tracking conditions. Experimental results show that both the video tracking and the integrated systems perform accurately and persistently under various scenarios involving multiple vehicles, driving speeds, and driving patterns. The results also validate and reiterate the importance of video tracking as an enabling technology in the field of radiation imaging.

Low energy gamma ray imaging with a detector array

Methods such as Compton imaging can be used to image a radiation field, including localizing different radioactive isotopes. Depth of interaction detection enables Compton imaging using Cadmium Zinc Telluride (CZT) detector for gamma ray energies above ~300 keV. We have developed an imaging technique for low energy gamma rays, using an array of CZT sensors, based on the non-uniform penetration of radiation into the interior of individual crystals, and radiation “shadows” cast by one detector crystal onto its neighbors. This mask-free imaging technique is ideal for a hand-held detector system because it avoids the need for the heavy collimator or masks typically used to image at low energies. A radiation source direction is reconstructed from the unique geometric shadow that develops when illuminating detector array. This shadow is based on the path length attenuation of the gamma as it passes through the detector material. This self-shielding technique can also be combined with high energy gamma ray Compton imaging to enhance radioisotope localization. We demonstrate this approach using simulations and measurement on a multi-crystal CZT detector.

3D filtered backprojection for curved detector axial cone-beam data on a playstation® 3

Increasingly large CT data sets in combination with more sophisticated reconstruction algorithms and data corrections place an expanding burden on computing platforms. Furthermore, traditional processors are increasingly unable to deliver the required performance for processing these CT data sets. Emerging computing platforms such as powerful graphics processing units (GPUs) and the cell broadband engine (CBE) show promise for handling this increased computational burden. In this paper, we report the results of implementing a 3D filtered backprojection algorithm for curved detector axial cone-beam CT data on the CBE. The development platform for this work is a Sony playstationreg 3, which includes a CBE.