How to check if any check box is checked in all nodes (parent to child) in Tree View in WPF Application?

Hi All,
I have a Delete button in WPF Application. I want this Delete button should enabled only if any checkbox is checked (either in Parent node or Child node) in TreeView.
If There is no check box checked in any node then Delete button should disabled. Delete button Enable/Disabled should work on checkbox selected and unselected. Please help me in this.
Thanks,