How can I set my CheckBoxes inside of my ListBox to be disabled

How can I set my CheckBoxes inside of my ListBox to be disabled?

XAML:

<GroupBox Header="A GroupBox" BorderThickness="2" Width="247" HorizontalAlignment="Left" VerticalAlignment="Top" Height="183" Margin="405,155,0,0">
    <Grid>
        <ListBox Name="MyListBoxThing" ItemsSource="{Binding MyItemsClassThing}" Height="151" Width="215" HorizontalAlignment="Left" VerticalAlignment="Top" ScrollViewer.VerticalScrollBarVisibility="Visible"  ScrollViewer.HorizontalScrollBarVisibility="Auto" Margin="10,0,0,0">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal">
                        <CheckBox  IsChecked="{Binding IsSelected, Mode=TwoWay}"  />
                        <TextBlock Text="{Binding Path=Name}"/>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</GroupBox>

Mainwindow.xaml.cs

public class MyItemsClassThing
{
    public string Name { get; set; }
    public bool IsSelected { get; set; }
}

The Problem: I'm trying to disable my CheckBox's dynamically that are inside of my listbox. But when I disable the ListBox it also disables my vertical scroll bar. So now I'm thinking that I should access the CheckBoxes inside of the Listbox inside of my groupbox and then disable them one by one. How can I do this?

I tried this, but had no luck:

var children = LogicalTreeHelper.GetChildren(MyListBoxThing);
foreach(var item in children)
{
    var c = item as CheckBox;
    c.IsEnabled = false;
}

I want to say like:

loop through the listbox
   if you find a check box
       checkbox.isenabled = false
   endif
end 

Thanks in advance