Multiscale Beagle Dog Mesh-Type Computational Phantoms for Preclinical Radionuclide Dosimetry
Abstract
Purpose
To develop tetrahedral mesh-type phantoms of the female and male beagle dog and perform Monte Carlo (MC) radiation transport simulations to compute specific absorbed fractions (SAFs) for monoenergetic photons, electrons and alpha particles. These canine phantoms include a skeletal microstructure model that allows the estimation of red bone marrow and endosteum dose.
Methods
Phantom geometries were based on cross-sectional photographs of a frozen female beagle, provided by Prof. Jin Seo Park at Ajou University, South Korea. These images, generated using methods analogous to those used in the Visible Human Project, were imported into 3D Slicer software and manually segmented to delineate the different tissue regions. Following the segmentation process, contours were converted into polygon mesh format and iteratively refined in Blender software. To create the male model, CT images were used to construct meshes representing testis and prostate, which then replaced the corresponding sex-specific organs in the female model. Values for trabecular volume fraction, trabecular number and cellularity factor of the beagle were used along human microCT spongiosa images and an in-house bone generator code to create microscale skeletal models. A blood volume distribution model was developed and used to calculate tissue densities and tissue elemental compositions. Models were converted into tetrahedral mesh format and used to perform MC simulations in PHITS to obtain SAFs and S-values.
Results
Male and female computational beagle phantoms were constructed in high-quality mesh format, featuring a detail skeletal model. MC radiation transport simulations were performed to compute SAFs and S-values for all source-target organ combinations for a variety of radionuclides relevant to preclinical dosimetry studies.
Conclusion
The computational beagle phantoms developed in this study have a variety of potential uses, particularly in the context of in-silico, preclinical dosimetry studies exploring the effects of radionuclide therapies. Work supported by grant P01 AI165380 with NIAID.