Development of a nonhuman primate computational phantom for radiation dosimetry

Abstract

Purpose The nonhuman primate (NHP) is an important animal model for evaluating the response of the human body to radiation exposure owing to similarities between its organ structure, genome, life span, and metabolism. However, there is a lack of radiation dosimetry estimations for NHPs. The aim of this work is to construct a computational phantom of NHPs and estimate absorbed fractions and specific absorbed fractions for internal radiation dosimetry. Materials and methods A female rhesus monkey was frozen and sectioned using a cryomacrotome. The transaxial sectioned images were imported into Adobe Photoshop for segmentation of internal organs. A total of 31 organs/tissues were identified and labeled. The segmented voxel phantom was then converted to a boundary representation (BREP) phantom to enable easy alteration of the phantom to mimic monkeys of different stature. The BREP model was then voxelized and imported into the MCNPX Monte Carlo radiation transport code for electron and photon dosimetry calculations. To estimate the appropriateness of using human phantoms as surrogate models for NHPs, absorbed fractions (AFs) and specific absorbed fractions (SAFs) of monoenergetic electrons and photons were calculated and compared with the ICRP reference newborn female phantom and a 1‐yr‐old female phantom. Results Considerable differences were observed for both self‐absorbed and cross‐absorbed doses for some organs between the NHP phantom and newborn phantom. For example, the ratios of the self‐absorbed SAF(stomach wall) Monkey to SAF(stomach wall) Newborn ranged from 0.06 at 10 keV to 0.29 at 3 MeV for photons while the corresponding ratios to cross‐absorbed SAF(liver→kidney) Monkey to SAF(liver→kidney) Newborn ranged from 0.78 at 50 keV to 5.78 at 10 keV for photons. Conversely, values of self‐absorbed SAF were much higher (ratios of 2.39–4.19) for the brain and much lower for the uterus (0.51–0.61) in the monkey model compared to the newborn phantom. These dose differences can be attributed to the disparities between organ masses, shapes, and positions between the two phantoms. Conclusions The developed NHP model can be exploited for the assessment of radiation dose to NHPs in preclinical radiation dosimetry studies and radiation therapy research.

Quantitative Tissue Pharmacokinetics and EPR Effect of AGuIX Nanoparticles: A Multimodal Imaging Study in an Orthotopic Glioblastoma Rat Model and Healthy Macaque

“…A (t) is calculated from the activity concentration in the organ given by PET and the volumes of the corresponding organ extrapolated from the average values listed in the literature. [ 63 ] A 0 is the injected activity. The measured part of the organ activity (during 6 days) can easily be numerically integrated by the trapezoidal rule.…”

Age‐dependent dose calculations for common PET radionuclides and brain radiotracers in nonhuman primate computational models

“…Given that the rhesus monkey is one of the most popular NHP strains used in preclinical research, we developed a series of anatomic models based on the original NURBS‐based realistic NHP model 13 derived from digital cryosection images of an 8‐year‐old female rhesus monkey according to published morphologic parameters and the body growth curve for this NHP species. The age, weight, and crown‐rump length values summarized in Table I were obtained from 5‐yr study data on the clinically healthy rhesus macaques 15 and used as basis for modification of the original NURBS‐based NHP model (anchor model).…”

“…In this regard, the development of realistic computational models mimicking the anatomy of NHPs is of paramount importance. 12 In this work, we used the original nonuniform rational Bspline surface (NURBS)-based NHP model developed by our group 13 to produce a series of models representing NHPs at 5 age periods (baby, infant, juvenile, young, and adult) between newborn and 192 months. Similar work was reported previously for computational rat models.…”

Voxelized scomber japonicus phantom and its application for internal dose evaluation by Monte Carlo calculations

“…Numerous voxelized phantoms have been developed for preclinical purposes, encompassing voxelized mouse phantoms [3][4][5][6][7][8][9][10][11][12][13] and voxelized rat phantoms [4,8,[14][15][16][17][18][19]. Furthermore, voxelized phantoms have been created for radiation dose calculation for a variety of non-human models, such as crab [20], trout [21], frog [22], monkey [23], flatfish [24] and canine [25]. These voxelized phantoms employed anatomic data obtained through medical imaging to produce highly detailed 3D digital renderings, which served as the geometric foundation for Monte Carlo calculations.…”