var checked = new Image(); 
var unchecked = new Image(); 

checked.src = getFullURLPrefix() + '/images/input/checked_radio.gif'; 
unchecked.src = getFullURLPrefix() + '/images/input/unchecked_radio.gif'; 

function SwitchImage(id_input) 
{ 
	
    if (document.getElementById("answer_"+id_input).checked == false) 
    {
    	document.getElementById("answer_"+id_input).checked = true; 
    	document['check_image_' + id_input].src = checked.src; 
    }
    RefreshAnswerImage();
   	
	
} 
function SwitchImageFromInput(id_input)
{
    if (document.getElementById("answer_"+id_input).checked == true) { 
        document['check_image_' + id_input].src = unchecked.src; 
    } else { 
        document['check_image_' + id_input].src = checked.src; 
    } 

}

function RefreshAnswerImage()
{
	var inputs = document.getElementsByName("answer");
	for(var i = 0; i < inputs.length; i++)
	{
 		if (inputs[i].checked == true)
		{
			document['check_image_' + i].src = checked.src; 
   		}
   		else
   		{
   			document['check_image_' + i].src = unchecked.src; 
   		}
	 } 
}