Multiple pinhole aperture design using a modified Uniform Cramer-Rao Bound

This work presents a design study of using multiple pinhole apertures in small animal SPECT imaging applications. The SPECT system is based on the use of an existing ADAC gamma camera. For quantifying the performance of a detector design, we used the minimum achievable variance at several locations in the images, given some constraints on the resulting spatial resolution. This approach was formerly proposed as the Uniform Cramer-Rao Bound (UCRB). In this work, we propose to use a resolution constraint that is imposed on the mean gradient vector. This partially overcomes the limitations of the former UCRB approach based on the bias-gradient norm constraint. We applied this method for studying the effect of design parameters, such as number of pinholes and pinhole size, on the performance of the detector system.