FreeMarker asset.get URL to small image version

Dear Community,

we'd like to show a thumbnail version of images. When I use ${asset.get('${imageSrc}')} I reveice a URL like: "#####.com/t5/image/serverpage/image-id/552iC100D3EF02B71784/image-size/large?v=1.0&px=999"

How can I retrieve the URL to the small image from the FreeMarker function, like: "#####.com/t5/image/serverpage/image-id/552iC100D3EF02B71784/image-size/small?v=1.0&px=999"?

Thank you, best regards,
clemensw