The XML for SQL Server Reporting Services Reports are stored in the ReportServer Database of the server. Its possible to pull the XML out and then use the contents to find which reports are using which tables etc. This can be very handy if you there is a change to a schema where logic in reports may need to be updated but you dont know which reports need to be looked at.
The below will place the XML into a table so you can use it to filter what you are after.
The below queries the table you created, adjusting the value of the @SQLToCheckFor variable will adjust which text to look for within the SQL Datasets of the SSRS XML.
Note this is set up for SQL2008, from memory its just a change of the http address from 2008 to 2005 etc.