Dynamic high resolution imaging of rats: design considerations

Researchers at the University of Washington were surveyed to determine the biological criteria for dynamic positron emission imaging of rats. To be useful, 3-mm isotropic resolution and 2-3-s time binning were desirable characteristics for such a dedicated tomograph. A single plane in which two objects of interest could be imaged simultaneously was considered acceptable. Multilayered detector designs were evaluated as a possible solution to the dynamic acquisition and high-resolution imaging requirements. The University of Washington photon history generator was used to generate data to investigate a tomograph´s sensitivity to true, scattered, and random coincidences for varying detector ring diameters. Intrinsic spatial uniformity advantages of multilayered detector designs over conventional detector designs were investigated using a Monte Carlo program. As a result, a modular two-layered detector prototype is being developed. A module will consist of a layer of five 3.5-mm-wide crystals and a layer of six 3.5-mm-wide crystals. It is believed that adequate sampling can be achieved with a stationary detector system using these modules. Economical crystal decoding strategies have been investigated, and simulations have been run to investigate optimum light channeling methods for block decoding strategies