The purpose of this study is to determine whether brain structural network properties change in brain tumor patients following fractionated, partial brain radiotherapy(RT). We applied graph theory to MRI-derived cortical thickness estimates in 54 patients pre and post-RT and examine global and local changes in network topology. Increases in global efficiency, transitivity, and modularity were observed post-RT compared to pre-RT. Decreases in local efficiency and clustering coefficient were seen in regions receiving higher doses of RT. Our findings demonstrate alterations in global and local network topology following RT in patients with primary brain tumors.