Clearing cache for an individual page when using URL rewriting

[Robert via DotNetMonster.com]

I'm doing URL rewriting for my web site, so there is only a single phyiscal web page (Index.aspx). All other web pages I construct dynamically. This is all working fine, but I want the ability to clear the cache for an individual page, and not for the entire site.

For example, when I do

HttpResponse.RemoveOutputCacheItem("/MySite/Index.aspx");

then the cache for the entire site is cleared.

How can I clear the cache for just one page
(e.g. Index.aspx?Page=Page1), which isn't a physical page.

Thanks.

Robert