OutputChached Exact for 2 pics

See more:

C#

ASP.NET

cache

Hi every one.
I cached my image folder in IIS(http headers).
But i have 2 pics in this folder that in any time i should show one of them. and these pics are in a Gridview and i change their visible by Sqldata source.

so i want 2 pics in this folder to not cached. so i dont set (Enable content expiration) for these 2 pics manualy and this check box is not checked for these 2pics.
Also i have this code in my page too :

Response.Cache.SetExpires(DateTime.Now.AddMonths(2));

But in my case , these 2 pics are cached too, and when i changed their visible, there is no change in website till i use CTRL+F5 .

How can i handle this case and make these 2 pics not cached?
Thanks in advance.