Browser cache problem(IE) for displaying new uploaded image with same name

/*By Jiangong SUN*/

In images management page of my back office, all the uploaded images are displayed in it.

But when i upload a new image with the same name for a existing image, the new uploaded image doesn't show immediately in IE 8 and 7(not tested in ie9).

I have to press "ctrl+F5" to clear the browser cache to display it. 

Here is my code:

                    if (File.Exists(Server.MapPath(filePath)))                        File.Delete(Server.MapPath(filePath));                    if (!File.Exists(Server.MapPath(filePath)))                        file.SaveAs(Server.MapPath(filePath));

I've tried to clear the browser cache with the following code: 

// Stop Caching in IEResponse.Cache.SetCacheability(System.Web.HttpCacheability.NoCache);// Stop Caching in FirefoxResponse.Cache.SetNoStore();

But it seems it doesn't work for this case, even if the code solved my browser cache problem recently. 

So i have to make it alternatively.

I forced it to load the image with a GUID id. 

imagePath = imagePath + "?id=" + Guid.NewGuid();

So even the image in browser cache has the same name with my newly uploaded image, the application will find the new image. In this way, the new image will be displayed immediately.