To be able to scan all site collections present in a Web Application including personal site collections created by individual users.

To grant a user or group administrator access to a given web application do as follows.

1. SharePoint 2007
   1. Go to SharePoint Central Administration.
   2. Click on the Application Management tab.
   3. Under Application Security click on Policy for Web Application
   4. Click Add Users
   5. Confirm your settings on the screen (defaults should be what you want) and click Next
   6. Now enter your user or group of users
   7. Click the box beside Full Control – Has full control.
   8. Click Finish
      
2. SharePoint 2010
   1. Go to SharePoint Central Administration.
   2. Click on the Application Management tab.
   3. Click on Manage Web Application
   4. From the list of Web Applications, select the Web Application that you want to add the new user to.
   5. Once the web application has been selected, click on the User Policy button in the Policy section
   6. Click Add Users
   7. Follow the screens to add the users with the Full Control permission and hit Finish