Room: Stars at Night Ballroom 1
Purpose: Sparing of microvasculature by microbeams is investigated by a bottom-up modelling approach initiated by endothelial cell radiosensitivity, survival of vascular branches and extended to network level viability of blood flow at given sample volume. An expendable stochastic model is tested for uniform and discrete dose profiles. Sensitivity of reduction in total branch length by beam diameter, dose magnitude and ratio of beams occupying the volume are experimentally measurable to better understand preservation of microvasculature by microbeams.
Methods: In silico microvascular model is used to generate a network of vascular branches in a volume with a spherical diameter of 1.3mm that is surrounded by tissue that provides supporting arterioles and venules to the volume of interest. Morphological parameters include the random node distribution, branch length and radii distribution for arterioles, venules and capillaries, and rules for vascular branch connections including the angle distribution between branches depending on blood flow directions, are implemented in the vascular network model. The model can also determine if any vascular branch pathway is â€˜effectively blockedâ€™ to blood flow by reduction in vasculature in the network.
Results: The stochastic model predicts dose dependent vasculature reduction in experimentally observable parameters; change in the total branch length, branch area, node distribution, distance to next branch for uniform and discrete dose profiles with varying beam diameter, and beam dose magnitude. The model predicts overall sparing effects of discrete beam dose profiles than uniform dose at given volume average absorbed dose. Network level analysis of available vascular branch pathways in spherical geometry highlights amplified reduction in blood flow by radiation dependent damage to vasculature.
Conclusion: In silico microvascular network model can be extended to different tissue models including the tumor vasculature incorporating the experimental morphological parameters to investigate dose dependent reduction in microvasculature for uniform and discrete irradiation of tissue.