Related Experiment Video
Updated: Jun 6, 2026
A Method for 3D Reconstruction and Virtual Reality Analysis of Glial and Neuronal Cells
Published on: September 28, 2019
Geometrical and Monte Carlo projectors in 3D PET reconstruction
Pablo Aguiar1, Magdalena Rafecas, Juan Enrique Ortuño
1Fundación IDICHUS/IDIS, Complexo Hospitalario Universitario de Santiago de Compostela, Departamento de Física de Partículas, Universidade de Santiago de Compostela, Spain. pablo.aguiar.fernandez@sergas.es
Purpose:
In the present work, the authors compare geometrical and Monte Carlo projectors in detail. The geometrical projectors considered were the conventional geometrical Siddon ray-tracer (S-RT) and the orthogonal distance-based ray-tracer (OD-RT), based on computing the orthogonal distance from the center of image voxel to the line-of-response. A comparison of these geometrical projectors was performed using different point spread function (PSF) models. The Monte Carlo-based method under consideration involves an extensive model of the system response matrix based on Monte Carlo simulations and is computed off-line and stored on disk.
Methods:
Comparisons were performed using simulated and experimental data of the commercial small animal PET scanner rPET.
Results:
The results demonstrate that the orthogonal distance-based ray-tracer and Siddon ray-tracer using PSF image-space convolutions yield better images in terms of contrast and spatial resolution than those obtained after using the conventional method and the multiray-based S-RT. Furthermore, the Monte Carlo-based method yields slight improvements in terms of contrast and spatial resolution with respect to these geometrical projectors.
Conclusions:
The orthogonal distance-based ray-tracer and Siddon ray-tracer using PSF image-space convolutions represent satisfactory alternatives to factorizing the system matrix or to the conventional on-the-fly ray-tracing methods for list-mode reconstruction, where an extensive modeling based on Monte Carlo simulations is unfeasible.
