Slippa spam i formulär?

<?php 
session_start();

$rand_code = $_SESSION['rand_code'];

unset($_SESSION['rand_code']);

if(isset($_POST['validator'])) { //'validator' är namnet på fältet där man skriver in verifieringskoden
if($_POST['validator'] != $rand_code)
{
die('Din verifieringskod stämde inte, <a href="javascript:history.go(-1)">försök en gång till</a>.');
}
else {
// Lägga till nya poster
} ?>

<?php /*

I formuläret skriver du så här:

<input type="text" name="validator" id="validator" size="4" />
<img src="random.php" alt="" width="60" height="20" vspace="1" align="top" />

*/

?>

<?php
session_start();

unset($_SESSION['rand_code']);
putenv('GDFONTPATH=' . realpath('./'));
if(empty($_SESSION['rand_code'])){
 $str = "";
 $length = 0;
 for($i = 0; $i < 4; $i++){
  $str .= chr(rand(97, 122));
 }
 $_SESSION['rand_code'] = $str;
}
$imgX = 60;
$imgY = 20;
$image = imagecreatetruecolor(60, 20);

$backgr_col = imagecolorallocate($image, 238,239,239);
$border_col = imagecolorallocate($image, 208,208,208);
$text_col = imagecolorallocate($image, 46,60,31);

imagefilledrectangle($image, 0, 0, 60, 20, $backgr_col);
imagerectangle($image, 0, 0, 59, 19, $border_col);

$font = "VeraSe.ttf";
$font_size = 10;
$angle = 0;
$box = imagettfbbox($font_size, $angle, $font, $_SESSION['rand_code']);
$x = (int)($imgX - $box[4]) / 2;
$y = (int)($imgY - $box[5]) / 2;
imagettftext($image, $font_size, $angle, $x, $y, $text_col, $font, $_SESSION['rand_code']);

header("Content-type: image/png");
imagepng($image);
imagedestroy ($image);
?>