Information Barriers for Imaging: The Single-Pixel Gamma Camera

Imaging technology is rarely used in arms control inspections due to the sensitive information that an image contains and the concern that it cannot be properly secured in a treaty verification context. However, this same sensitive information, specifically a direct view of the form and function of the items under inspection, could be used for robust arms control inspections. We are exploring methods of image analysis with information protection mechanisms built in, such as an immediate transform to reduce the dimensionality of the image data to a non-sensitive set of numbers. Here, we introduce one such method, the single-pixel gamma camera (SPGC). We utilize the methodology of the single-pixel optical camera and compressive sensing to capture the spa- tial features of an inspected object without ever actually forming the image. The inspection would be accomplished with a gamma-opaque, randomly-etched mask on a translation/rotation stage, a single large-area gamma detector, and a high-energy X-ray source. Each data point would be the total brightness produced in the gamma detector from the gamma flux that has passed through the inspected object and the mask. Repeating this measurement with the mask in various positions forms the compressively sensed data vector. In this way, the spatial information of the image is captured in the data vector while an image is never actually formed. We present the theory behind this method and estimate performance with simulated inspections. We demonstrate the potential for robustness of the compressively sensed data set to be used as a template for inspection of treaty items and discuss its potential as a secure inspection method.