search a tag except for certain attribute

[pat]

Hi, I hope someone knows the answer..
I'm trying to find some html-tags which lack certain attributes. I want to find all <img> tags which don't contain the attribute 'alt' and end with />.

I've tried the following:
<img\( [^/alt]*\)>
but that doesn't work..

So, tags like this must be excluded:
<img src="xxx" alt="" border="0" width="10" height="10" />

Thanks,
Pat.