How to start a radiobutton checked = true in a WPF MVVM application

How to start a radiobutton checked = true in a WPF MVVM application

Hi Basically I have a WPF application using the MVVM pattern.
This is my ViewModel:
namespace enLoja.WPF.ViewModel.Relatórios
{
public class SEL_PG_C_ALIViewModel : ViewModelBase
{
private readonly ICAD_EF_C_ALIService _cadEfCAliService;
//Commands
public RelayCommand OnLoaded { get; set; }
public RelayCommand Gerar { get; set; }
public SEL_PG_C_ALIViewModel(ICAD_EF_C_ALIService cadEfCAliService)
{
_cadEfCAliService = cadEfCAliService;
IsDataLoaded = false;
OnLoaded = new RelayCommand(OnLoadedExecute);
Gerar = new RelayCommand(GerarExecute, GerarCanExecute);
}
public async void Load()
{
await Task.Factory.StartNew(() =>
{
IsDataLoaded = true;
RaisePropertyChanged("IsDataLoaded");
});
}
public bool CodigoChecked { get; set; }
public bool DescricaoChecked { get; set; }
public bool IsDataLoaded { get; set; }
#region Commands Execute
public void OnLoadedExecute()
{
Load();
}
public void GerarExecute()
{
var parameters = new Dictionary<string, string>();
if (CodigoChecked)
{
parameters.Add("Order", "Código");
}
if (DescricaoChecked)
{
parameters.Add("Order", "Descrição");
}
IEnumerable<CAD_EF_C_ALI> query =
_cadEfCAliService.GetCAD_EF_C_ALI();
var empresaSelecionada = new List<CAD_EF_C_PAR> {
((App)Application.Current).EmpresaSelecionada };
var reportWindow = new REL_PG_C_ALI(query.ToList(),
parameters, empresaSelecionada);
reportWindow.ShowDialog();
}
public bool GerarCanExecute()
{
return (IsDataLoaded);
}