Terminate implicit session w/linq?

[Efitap]

Hello, experts!

I need help with a scenario:

I have a photography server that builds image paths dynamically to clients for downloading. This works as intended except for the following:

Each time a viewer wants an image preview, a new session is created on the server, terminating only one hour later. When there is lots of traffic, the sessions accumulate, and end up overwhelming the server.

I initially loaded the image uri more or less like this:

-- snip --
string xmlSourceUrl = GetImageUrl( );

XElement sourceRoot = XElement.Load( xmlSourceUrl );

string result = ( from file in sourceRoot.Descendants( "PreviewUrl" ) select sourceRoot.Value ).Single< string >( );
-- snip --

Which is bad. It looks like linq for Xml supports loading xml directly over http, but there is no way to tell it afterwards that the session should end immediately.

I tried using a WebClient object, but I cannot find a "Terminate", "Close", "Abandon" or any other function to indicate that I would like the session to end immediately after reading the stream.
Here is how it looks:

			// Create a webclient object to read with
			WebClient wc = new WebClient( );
			
			// prepare a reader object
			TextReader reader = new StreamReader( wc.OpenRead( completeUrl ) );

			/// To XElement using the reader
			XElement result = XElement.Load( reader , LoadOptions.None );

			// Close the reader
			reader.Close( );

			// client goes out of scope here - does session terminate?
			return result;

Can anyone help please?