A Geant4 simulation for three-dimensional proton imaging of microscopic samples

Area of Science:

• Physics
• Microscopy
• Nanotechnology

Background:

• Proton imaging enables high-resolution 3D analysis of microscopic samples using Scanning Transmission Ion Microscopy (STIM) and Particle Induced X-ray Emission (PIXE).
• In situ quantification of nanoparticles in biological models like Caenorhabditis elegans (C. elegans) is crucial for nanotoxicology.
• Current methods involve sample dehydration and data reduction via inversion algorithms to determine mass density and chemical content.

Purpose of the Study:

• To investigate the impact of data reduction processes on 3D proton tomography.
• To determine optimal parameters for 3D STIM imaging.
• To develop reference data for PIXE tomography studies.

Main Methods:

• Development of a Monte Carlo simulation using the Geant4 toolkit.
• Creation of numerical phantoms, including a C. elegans phantom, based on experimental data.
• Comparison of reconstructed tomographic images with reference phantoms under varying simulation and reconstruction conditions.

Main Results:

• The study identified 20 protons per shot as the optimal number for 3D STIM imaging based on relative error analysis.
• Numerical phantoms proved effective for evaluating data reduction algorithms.
• Preliminary PIXE tomography results highlight the utility of phantoms for X-ray attenuation studies.

Conclusions:

• The optimal number of protons per shot for 3D STIM imaging is 20.
• Numerical phantoms are valuable tools for validating proton imaging techniques and data reduction methods.
• Further research using phantoms is recommended for PIXE tomography of thick samples.