Fast hybrid SPECT simulation including efficient septal penetration modelling (SP-PSF)

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Computational Physics

Background:

• Single Photon Emission Computed Tomography (SPECT) images are often degraded by scattered photons and septal penetration.
• Accurate modeling of photon transport is crucial for quantitative SPECT imaging and image reconstruction.

Purpose of the Study:

• To extend a Monte Carlo software for SPECT simulations to include septal penetration (SP) effects efficiently.
• To accelerate the simulation of SP photons without significant loss of accuracy for various isotopes and collimators.

Main Methods:

• Developed a fast method for SP photon simulation using object attenuation and a scalable septal penetration point spread function (SP-PSF).
• Combined coarse sampling, detector pixel grid interpolation, and thresholding of SP-PSF elements to accelerate simulation.
• Integrated SP-PSF simulation into a Convolution-based Forced Detection (CFD) Monte Carlo simulator.

Main Results:

• Achieved a four-orders-of-magnitude acceleration in SP simulation with minimal accuracy reduction.
• Added only 10% computational overhead to the existing CFD-based Monte Carlo simulator.
• Enabled SPECT simulations of patient-like distributions, including SP, in under 5 seconds per projection angle.

Conclusions:

• The enhanced Monte Carlo simulator efficiently models both primary and septal penetrated photons in SPECT.
• The simulator is suitable for 3D model-based reconstruction and as a fast dataset generator for image processing and observer studies.
• This advancement facilitates more accurate and faster SPECT image analysis and development.