Comparison of different imaging geometries of brain SPECT systems

Since many different configurations of brain SPECT systems are available for clinical imaging recently, it is informative to investigate if there are much differences in their performance potential. However, the variation of system configurations and performance characteristics make direct comparisons difficult. To clarify the confusion, the authors have developed a method to analyze the relative merits of different basic system geometries and evaluating the potential for different system configurations. This method is based on the calculated system geometric efficiency (SGE) of each configuration under the condition that the reconstructed spatial resolution are normalized. In the normalization process, the design parameters and performances of the collimators were iteratively adjusted to match the reconstructed resolution of an appropriately defined reference specifications. After the collimator was normalized, the geometric efficiency (GE) of the collimator was calculated by integrating the point source geometric efficiency (PSGE) over a brain source model with narrow-beam attenuation effect imposed. Based on the calculated GE for each collimator, the SGE is derived for each system configuration. This analysis was performed for many existing geometries of brain SPECT systems with different detector-collimator configurations of commercial interest