php xml parsing for get img src

This is my second question. The following link is full code.

PHP How can use img in 'description'

now i want to get img src(URL) from $query[$j]['description'] = $item_desc;. How can i get that?

I've read following link already. but it did not help me

How to parse <img src="value" from this XML by using DOM?

PHP XML CDATA parsing