media tag

<?php
$media_items = get_attachments_by_media_tags('media_tags=$tag-name&size=thumb');
if ($media_items) {
echo '<ul>';
foreach ($media_items as $mymedia) {
$fullSize = wp_get_attachment_url($mymedia->ID);
$thumbnail = wp_get_attachment_thumb_url($mymedia->ID, 'thumb');
echo '<li><a href="' . $fullSize . '" rel="shadowbox[set1]" title="Fullscreen" ><img src="'.$thumbnail.'" /></a>
<span>This photo belongs to post: <a href="/summer-holiday">Summer holiday</a>, <a href="/best-of-2012">Best of 2012</a></span>
</li>'; }
echo '</ul>'; }  ?>