Optimization of pinhole emission imaging systems for small animal imaging

There has been a surge of interest in the design of small animal imaging systems that use radioactive tracers to track in vivo quantities such as tumor growth or spread. For single-photon radiotracers, one needs a blocking aperture, such as a pinhole, multi-pinhole aperture or collimator, to form images. Here we consider a single pinhole. For engineers, the pinhole design, especially its diameter, is crucial in that it controls a noise-resolution tradeoff, and this tradeoff ultimately determines the ability of a human observer to find and detect the tumor. We considered a single-pinhole planar emission imaging system and addressed the following engineering question what pinhole diameter allows the best possible performance in both detecting and localizing a signal (e.g. tumor) embedded in the noisy image We applied recent theoretical developments from our group to answer this question by using a mathematical ideal observer. If the only source of noise is radiation noise, then we demonstrate the result that a very large aperture leading to very blurry images is best.