System Response Matrix Calculation Based on Distance-Driven Model and Solid Angle Model for Dual-Head PET System

The dual-head positron emission tomography (PET) systems have an importance role in the preclinical and clinical applications. This paper focuses on developing a simplified model based on distance-driven (DD) and solid angle method to calculate the system response matrix (SRM) for the dual-head PET system. The subsampling schemes, including the subvoxel scheme and multi-DD scheme were introduced. The full width at half maximum (FWHM), coefficient of variation (COV), and contrast were computed and compared with that of using the Monte Carlo (MC)-based and multiray methods. In this paper, the dual-head PET system is configured with a 5 cm separation and
$52 \times 104$
mm
³
detection area of each head. The size of each crystal is
$13\times 1.89\times 1.89$
mm
³
. The results indicate that the rods with 1.0 mm diameter are resolved basically with the 100th iteration when the voxel is virtually divided into
$2\times 2\times 2$
and
$4\times 4\times 4$
subvoxels, which is comparable to that with the MC-based SRM. When the voxel is divided into four cuboid-shaped subvoxels, the rods with 1.0 mm diameter are resolved with the 80th iteration and the COV performs well in the simulation experiment. Overall, the proposed SRM model achieves a good compromise between image quality and calculation time.