Checkbox is checked or not C# WPF

How can I check if checkbox in listview are checked or not? If I check a row, the budget decrease. If I uncheck the row, the budget increase. I know that it is wrong, but I don't know how to do it.

private void CheckBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        long g;
        foreach(Player item in lv_player.Items)
        {
            g = Convert.ToInt64(item.Value);
            if (item.IsChecked == false)
            {
                budget += g;
                Team.Add(item);
            }
            else
            {
                budget -= g;
                Team.Remove(item);
            }
            lab_budget.Content = budget;
        }
    }

XAML

    <ListView Name="lv_player" Grid.Column="0" HorizontalAlignment="Left" Height="234" Margin="10,10,0,0" VerticalAlignment="Top" 
                       ItemsSource="{Binding}" SelectionMode="Multiple" Width="557">
                <ListView.View>
                    <GridView>
                        <GridViewColumn>
                            <GridViewColumn.CellTemplate>
                                <DataTemplate>
                                    <CheckBox Selector.SelectionChanged="CheckBox_SelectionChanged" ToggleButton.Unchecked="CheckBox_Unchecked" Checked="CheckBox_Checked" IsChecked="{Binding Path=IsSelected, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListViewItem}}}"/>
                                </DataTemplate>
                            </GridViewColumn.CellTemplate>
                        </GridViewColumn>
                        <GridViewColumn Header="Name" Width="150" DisplayMemberBinding="{Binding Name}"/>
                    </GridView>
                </ListView.View>
            </ListView>

Class Player Class Player