Xamarin, ListView, How to get values from checkbox in ListView?

I have a ListView with Label and Checkbox

I want to implement a button lister that will get all checked items from my ListView

This is the ListView

<ListView ItemsSource="{Binding OCParticipantsTable}" 
HasUnevenRows="True" 
x:Name="dsfdf">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
 <StackLayout>
 <Label Text="{Binding FirstName_}"/>
 <CheckBox/>
 </StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>

This is the ItemsSource property:

private ObservableCollection<ParticipantsTable> _OCParticipantsTable = 
            new ObservableCollection<ParticipantsTable>();
        public ObservableCollection<ParticipantsTable> OCParticipantsTable
        {
            get { return _OCParticipantsTable; }
            set
            {
                if (_OCParticipantsTable != value)
                {
                    _OCParticipantsTable = value;
                    OnPropertyChanged("ListOfItems");
                }
            }
        }

How can I implement a button lister that will get all checked items from my ListView ?

Something like that:

foreach (var pt in dsfdf.ItemsSource)
            {
                if (pt.CheckBox.IsChecked)
                {
                    // do something...
                }
            }