PHP RSS filter

<?php

if(isset($_GET['feedUrl'])) {
$feedUrl = $_GET['feedUrl'];
} else {
die('No feed url provided (feedUrl parameter)');
}

if(isset($_GET['feedFilterKeywords'])) {
$feedFilterKeywords = $_GET['feedFilterKeywords'];
} else {
die('No feed filter keywords provided (feedFilterKeywords parameter separated by | character)');
}

$feedFilterKeywords = array_map('trim', explode('|', $feedFilterKeywords));
$originalFeed = simplexml_load_file($feedUrl);
$parsedFeedItems = $originalFeed->xpath('/rss/channel/item');

foreach ($parsedFeedItems as $index => $item) {
foreach ($feedFilterKeywords as $filterKeyword) {
if (strpos(strtolower($item->title), strtolower($filterKeyword)) !== false) {
unset($parsedFeedItems[$index]);
break;
}
}
}

$xmlParsedFeedItems = '';
foreach($parsedFeedItems as $feedItem) {
$xmlParsedFeedItems .= $feedItem->asXML();
}
$originalFeedWithoutItems = preg_replace('/<item>(.*)<\/item>/s', '', $originalFeed->asXML());
$parsedFeedXML = str_replace('</channel>', $xmlParsedFeedItems . '</channel>', $originalFeedWithoutItems);

header("Content-type: text/xml");
die($parsedFeedXML);