A gamma ray imager using clustered non-redundant array coded aperture

This paper presents the design and initial experimental results of a gamma camera using a coded aperture with clustered non-redundant array pattern. This system is based on the use of 5" position sensitive photomultiplier tube coupled to pixelated BGO array with 2×2×10mm³ pixels. The PSPMT is readout by the IDEAS VA-MCR system with a costume made front electronic. This gamma camera was designed for imaging gamma rays with a broad energy range. The collimator plate was made of Tungsten of 8 mm thick for reducing the effect of gamma ray penetration. For imaging source objects with a relatively large angular extent and high background, the use of clustered NRA offers great flexibility in aperture design that provides a wide view angle and a controlled data multiplexing. In order to replace the time consuming Monte Carlo simulations, we also presented an analytical method for calculating performance indices, such as pixel-wise signal-to-noise ratio and resolution/variance tradeoffs achievable with different detector designs. This helps to select an approximate aperture for given imaging tasks.