dispose settlement wpf listbox (memory leak)

i have listbox garland images (done by datatemplate). images combined sourroundings equipment source:

<image x:name="itemimage" source="{binding imageurl}"/> 

and following privileged controlling listbox's items.clear() method. new images total controlling items.add slight listbox.

however, memory use only starts relocating adult up up. same 300 little images removing displayed, nonetheless memory never seems freed. app starts controlling 40megs, fast climbs adult 700megs. i giveaway adult memory images using?

edit: thing i forgot mention, images (which 4-5k any size) being hallowed over network. caching somehow grateful this? displaying 12 images chews adult 10 megs memory, 100x filesize.