PHP RSS Reader

我想用PHP寫一個RSS Reader, 但有一個Item叫<content:encoded>唔知點Read呀, 我係用PHP DomDocument();寫架!!

XML:
<item>
<title>Testing RSS</title>
<link>http://www.testing.com/</link>
<content:encoded>Content</content:encoded>
</item>

PHP Code:
$item = $dom0->getElementsByTagName("item")->item(0);
$title= $item->getElementsByTagName("title")->item(0)->childNodes->item(0)->nodeValue;
$content = $item->getElementsByTagName("content:encoded")->item(0)->childNodes->item(0)->nodeValue;

P.S.: 我Read到<title>同<link>架, 係Read唔到<content:encoded>咋...

謝謝!!