Author: Daylin Barroso, Chris Beekman, Wesley E. Bolch, Natalia Estefania Carrasco-Rojas, Robert Joseph Dawson, Walter Murfee, Harald Paganetti, Andrew Robert Sforza, Julia D. Withrow 👨🔬
Affiliation: Massachusetts General Hospital - Harvard Medical School, Massachusetts General Hospital, University of Florida 🌍
Purpose: To develop methods for quantifying the interaction of radiation with blood in the mouse whole body (MOBY) phantom for dosimetric applications. The most important of these are modeling the distribution of radionuclides decaying in blood vessels, and computation of blood dose volume histograms (DVHs) for external radiation sources.
Methods: NanoCT images were obtained of the mouse kidney, liver, brain, spleen and heart that have been perfused with MICROFIL® polymer. These images were then compiled into a mesh model and skeletonized. This mesh was then put through an in-house tracking algorithm to determine vessel type, position and connections. This vascular network was then trimmed back to a vessel radius of 20 µm. Analysis of vessel length and radius of the trimmed network was then used to inform the generation of an algorithmically generated blood vessel model down to a 10 µm radius.
Results: Image-based meshes and vascular trees were generated with resolution down to the meta-arteriole scale (10 µm < blood vessel radius < 50 µm) at maximum. Artificial models of mouse major blood vessels were also constructed.
Conclusion: Models of the vasculature within mice organs were generated directly from anatomical information, allowing for a significantly more anatomically rigorous model of blood vasculature in MOBY. The models that were created are primarily useful for short-range radiopharmaceutical dosimetry where location information provided is more important. In addition, the models can be used in conjunction with a blood particle tracking software such as Massachusetts General Hospital’s HEDOS to make blood dose calculation significantly more realistic for treatment planning purposes. This information holds promise to significantly reduce or even prevent radiation-induced lymphopenia, however further preclinical trials are needed to confirm this. Making these models for the laboratory rat would also be useful for rat preclinical trials and are a logical next step.