Associated particle neutron elemental imaging in vivo: A feasibility study

Area of Science:

• Medical Imaging
• Nuclear Physics
• Computational Modeling

Background:

• Accurate in vivo elemental analysis is crucial for diagnosing and monitoring various medical conditions.
• Current methods for determining liver iron concentration have limitations in precision and invasiveness.
• Associated Particle Neutron Elemental Imaging (APNEI) offers a potential non-invasive approach for elemental quantification.

Purpose of the Study:

• To develop a Monte Carlo simulation model for in vivo APNEI.
• To investigate the feasibility of using this APNEI model to determine iron distribution within a human liver.
• To establish a computational framework for evaluating APNEI's potential in biomedical applications.

Main Methods:

• A Monte Carlo N-Particle (MCNP) simulation was created, incorporating human body geometry, D+D neutron source, and iron-specific parameters.
• Iron inelastic scatter gamma rays were simulated using the f8 tally to quantify signal at varying iron concentrations.
• Dose calculations (f4 tally) were performed to estimate organ and whole-body radiation exposure, informing data collection limits.

Main Results:

• The model predicts that 143 iron inelastic scatter gamma ray counts are ideal for detecting 1000 ppm iron in a 1 cm³ liver voxel, within a 5 mSv liver dose limit.
• A 2D image of iron distribution with 1 cm resolution is achievable at 1000 ppm iron concentration.
• The estimated whole-body dose for image acquisition is 0.82 mSv, with simulated uncertainties reflecting real-world conditions.

Conclusions:

• In vivo APNEI demonstrates feasibility for elemental analysis, including iron in the liver, contingent on addressing timing, sensitivity, and resolution challenges.
• Further experimental validation is necessary to determine the precise detection limits and achievable image resolution.
• The current idealized model may overestimate signal, necessitating refinement for practical experimental setups.