DataGrid Controls WPF

Question

I want to use radio button in datagrid (wpf) in a way that, instead of showing data in text format in datagrid column, I want the data to be shown in radio button. But can't find the way to that. As it gives error in FindControl Function.

                <DataGrid.Columns>
                    <DataGridTemplateColumn>
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center" Orientation="Horizontal">
                                    <RadioButton Name="rb_Present" GroupName="CMGrp" Content="Present" IsChecked="{Binding Path=is_selected, Mode=TwoWay}"></RadioButton>
                                    <RadioButton Name="rb_Late" GroupName="CMGrp" Content="Late" IsChecked="{Binding Path=is_selected, Mode=TwoWay}"></RadioButton>
                                    <RadioButton Name="rb_Absent" GroupName="CMGrp" Content="Absent" IsChecked="{Binding Path=is_selected, Mode=TwoWay}"></RadioButton>
                                </StackPanel>
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                </DataGrid.Columns>
            </DataGrid>


foreach (GridView row in dtAttendance.Items)
            {
                RadioButton rb =  (RadioButton)row.FindName("RadioButton1");
            }
            dtAttendance.ItemsSource = dt.DefaultView;
        }