Development of a nonhuman primate computational phantom for radiation dosimetry

Area of Science:

• Medical Physics
• Radiological Sciences
• Computational Biology

Background:

• Nonhuman primates (NHPs) are crucial animal models for radiation exposure studies due to physiological similarities with humans.
• Accurate internal radiation dosimetry is lacking for NHPs, hindering precise dose assessment in research and preclinical studies.

Purpose of the Study:

• To construct a computational phantom of a female rhesus monkey.
• To estimate absorbed fractions (AFs) and specific absorbed fractions (SAFs) for internal radiation dosimetry in NHPs.
• To compare NHP dosimetry estimations with established human phantoms.

Main Methods:

• A female rhesus monkey was cryosectioned, and organs were segmented to create a voxel phantom.
• The voxel phantom was converted to a boundary representation (BREP) for scalability.
• MCNPX Monte Carlo code was used to calculate electron and photon AFs and SAFs.
• Calculated values were compared with the ICRP reference newborn female phantom.

Main Results:

• Significant differences in self- and cross-absorbed doses were observed between the NHP and newborn human phantoms.
• Organ-specific dose discrepancies were noted, with higher SAFs in the NHP brain and lower SAFs in the uterus compared to the newborn phantom.
• These variations are attributed to differences in organ mass, shape, and spatial arrangement.

Conclusions:

• The developed NHP computational phantom is a valuable tool for radiation dosimetry in preclinical research.
• This model enhances the accuracy of radiation dose assessment in nonhuman primates.
• It supports advancements in radiation therapy research and NHP radiation safety protocols.