如何从HierarchicalDataTemplate项中获取TreeViewItem？

<TreeView x:Name="myTreeView">
    <TreeView.ItemTemplate>
        <HierarchicalDataTemplate ItemsSource="{Binding Children}">
            <TextBlock Text="{Binding Name}"/>
        </HierarchicalDataTemplate>
    </TreeView.ItemTemplate>
</TreeView>

public class TreeViewItemModel
{
    public string Name { get; set; }
    public ObservableCollection<TreeViewItemModel> Children { get; set; }
}

private TreeViewItemModel CreateItem(string name, int level)
{
    TreeViewItemModel item = new TreeViewItemModel
    {
        Name = name,
        Children = new ObservableCollection<TreeViewItemModel>()
    };

    // 添加子项
    for (int i = 0; i< level; i++)
    {
        item.Children.Add(CreateItem("Child " + i, level - 1));
    }

    return item;
}

ObservableCollection<TreeViewItemModel> items = new ObservableCollection<TreeViewItemModel>();

for (int i = 0; i < 5; i++)
{
    items.Add(CreateItem("Item " + i, 2));
}

myTreeView.ItemsSource = items;