Vinh Nguyen

Document Type: Master's Thesis
Name: Vinh Nguyen
Email address: vnguyen@bme.utmem.edu
Title: Late Effects of Ionizing Radiation on Normal Microvascular Networks
Degree: Master of Science
Program: Biomedical Engineering
Research Advisor: Mohammad F. Kiani
Advisor's email: mkiani@utmem1.utmem.edu
Committee Members: Eugene C. Eckstein
James T. Dalton
 
 
Keywords: ionizing radiation, microcirculation, microvascular network, late effects, blood flow
Availability: Release the entire work for World Access 8/00.

Abstract

Therapeutic doses of ionizing radiation result in changes in the structure and function of
microvascular networks in normal tissue. Previously, we reported on the early effects of ionizing
radiation on microvascular networks at 3, 7, and 30 days post-irradiation [1-3]. Data from the
early time points suggested that ionizing radiation significantly alters the structure and function of
microvascular networks and interferes with the normal processes of vessel maturation. Here, we
present our findings on the late effects of ionizing radiation on normal tissue microvasculature at
60, 120, and 180 days post-irradiation. The cremaster muscle of Golden Syrian hamster was
locally irradiated (single 10Gy dose, delivered at 2 Gy/min). Microvascular networks were
selected in reference to a well-defined location in the tissue to reduce heterogeneity due to spatial
variation. Intravital microscopy was used to measure both structural and functional parameters.
Geographic Information Systems (GIS) technology was used to establish network topology. At all
late time points, the diameter of irradiated vessels was significantly larger than control. Red blood
cell velocity in irradiated vessels showed a significant decrease from controls at 120 days post-irradiation
and an increase at 180 days post-irradiation. Others parameters such as lineal density,
tortuosity, vessel length, and vessel tone showed no significant difference between control and
irradiated vessels. The hamster cremaster muscle proved to be an effective model in examining the
effects of radiation on normal microvascular tissue. Together our early effect and late effect
studies suggest that significant changes occur in structural and functional parameters of irradiated
microvascular networks and, hence, that radiation therapy may alter the oxygen delivery capacity
of normal tissue microvascular networks.

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Revised 23 May 2002