PHP : Get XML Value with colon and attributes

Question

Below is the Xml file,, I need to retreive value between <im:name> and </im:name> , i.e Dental Surgery .and also value between <im:image height="75"> and </im:image> , i.e http://a478.phobos.apple.com/.75x75-65.png

<entry>
   <im:name>Dental Surgery</im:name>  
    <im:image height="53">
    http://a1962.phobos.apple.com/53x53-50.png
    </im:image>
    <im:image height="75">
    http://a478.phobos.apple.com/.75x75-65.png
    </im:image>
    <im:image height="100">
    http://a683.phobos.apple.com/100x100-75.png
    </im:image>
</entry>

I tried below code but dont work

  $entry->im->name;