Single photon emission computerized tomographic (SPECT) images often suffer from low resolution and low count
density. To improve spatial resolution of SPECT it is possible to use a pinhole collimator; however, this further reduces
the system sensitivity. A potential solution to this problem is to use coded apertures, which offers increased sensitivity
by using multiple pinholes, at the cost of increased image reconstruction time.
A generic reconstruction algorithm has been developed which allows for arbitrary acquisition geometry via affine
transforms (translation and rotation). The reconstruction process uses a (Siddon) ray projector, the expectation
maximization (EM) algorithm and a 1 to n pinhole position matrix. Iteration times scale as a function of the number of
pinholes in the collimator. Resolution recovery has also been incorporated into the reconstruction algorithm.
The algorithm developed allows for the investigation of optimal imaging settings for small animal imaging. Simulated
acquisitions of an ex-vivo rat heart with 1, 5 and 8 pinholes, over 360 degree acquisition, showing that multi-pinhole
imaging can be successfully applied to rat cardiac imaging. Further refinement of the acquisition parameters, such as
image overlap, collimator pinhole configuration and geometrical imaging configuration, will predict the theoretical
settings for quantitative cardiac multi-pinhole SPECT imaging.