TreeView with CheckBoxes dynamically WPF. How to know the name of the elements selected

I have a code that displays the files and folders names in a TreeView and put a checkbox from each element. What I don't know how to do is how to know the elements in the TreeView that are selected with the checkboxes.

XAML:

<TreeView Name="treeView" Grid.Row="10" Grid.ColumnSpan="3">
        <TreeView.Resources>
            <Style TargetType="{x:Type TreeViewItem}">
                <Setter Property="HeaderTemplate">
                    <Setter.Value>
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal">
                                <CheckBox Focusable="False" IsChecked="False" VerticalAlignment="Center"/>
                                <TextBlock Text="{Binding}" Margin="5,0" />
                            </StackPanel>
                        </DataTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
        </TreeView.Resources>
    </TreeView>

Program:

    DirectoryInfo di = new DirectoryInfo(folder);
    treeView.Items.Add(getTree(di));

    public TreeViewItem getTree(DirectoryInfo di)
    {
        TreeViewItem item = new TreeViewItem();
        item.Header = di.Name;
        item.FontWeight = FontWeights.Normal;
        foreach (DirectoryInfo s in di.GetDirectories())
        {
            item.Items.Add(getTree(s)); 
        }
        foreach (FileInfo fi in di.GetFiles())
        {
            item.Items.Add(fi.Name);
        }
        return item;
    }