Expanding SimSET to include block detectors: performance with pseudo-blocks and a true block model.

Area of Science:

• Medical Physics
• Computational Imaging
• Nuclear Medicine

Background:

• SimSET, a photon tracking simulation package, currently models detectors as solid annuli.
• This simplification does not accurately represent the geometric nature of block detectors used in modern scanners.
• Discrepancies between simulation and actual scanner measurements arise from this geometric simplification.

Purpose of the Study:

• To introduce and evaluate two distinct approaches for implementing block detectors within the SimSET simulation package.
• To compare the performance of these new implementations against the conventional SimSET model and real-world scanner data.
• To assess the impact of block detector geometry on simulation accuracy and efficiency.

Main Methods:

• A pseudo-block approximation was developed by modifying SimSET to discard interactions in specific annulus segments, creating annulus-segment blocks.
• A more comprehensive modification was planned to implement true rectangular blocks in the SimSET detector module.
• Both implementations were compared to conventional SimSET results and data from a GE DSTE PET/CT scanner, evaluating sensitivities, crystal maps, energy spectra, and simulation run times.

Main Results:

• Both implemented block structure approaches showed improved agreement with scanner measurements compared to the conventional SimSET model.
• The pseudo-block approximation offered a quick and easy method to enhance SimSET's accuracy.
• The true rectangular block implementation is expected to provide greater variability and fidelity to detail.

Conclusions:

• Implementing block detector structures in SimSET significantly improves simulation accuracy by addressing geometric discrepancies.
• The pseudo-block approximation is a valuable interim solution for enhancing SimSET's performance.
• Further development of true rectangular block implementation promises even greater accuracy and realism in simulations for positron emission tomography (PET) scanners.