Prova a fare in questo modo:
Codice PHP:
<?PHP
$desclightbox = "<table><tr><td>prova</td><td>prova2<td></tr></table>";
?>
[url="./images/img_big/<?PHP echo $Foto; ?>.jpg"][img]./images/img_small/<?PHP echo $Foto; ?>.jpg[/img]';" width="60" height="60" style="border:1px solid white;">[/url]