Get my TextBox cell from CheckBox cell event inside ListViewItem

I have ListView and each ListViewItem contains CheckBox and 2 TextBox:

<ListView.Resources>
    <DataTemplate x:Key="CheckBoxCell">
        <CheckBox x:Name="checkboxIsChecked"
              IsChecked="{Binding Path=IsChecked}"
              Style="{StaticResource CheckBoxListViewCellDefaultStyle}"
              Checked="checkboxIsChecked_Checked"
              Unchecked="checkboxIsChecked_Unchecked"/>
    </DataTemplate>

    <DataTemplate x:Key="textboxOriginalIpAddressCell">
            <TextBox Controls:TextBoxHelper.ClearTextButton="False"
                     Controls:TextBoxHelper.Watermark="ipv4 only"
                     LostFocus="textboxOriginalIpAddressCell_LostFocus"/>                                   
    </DataTemplate>
</ListView.Resources>

Now i wonder how to get my TextBox from my checkboxIsChecked_Unchecked event:

private void checkboxIsChecked_Unchecked(object sender, RoutedEventArgs e)
{
    // ?
}

Any ideas ?