What about something like this? (using jQuery):

$('input:radio').each(function() {

  if($(this).is(':checked')) {

    // You have a checked radio button here...

  } 

  else {

    // Or an unchecked one here...

  }

});

You can also loop through all the checked radio buttons like this, if you prefer:

$('input:radio:checked').each(function() {

   // Iterate through all checked radio buttons

});