Selecting Image with selectbox field in the panel

First project with kurby - so please be gentle.

I am trying to call the source from an image which i set in the blueprints (“iratap”) with an selectboxfield.

<img class="img-responsive" src="<?php echo $data->url(), "/", $data->iratap()?>" alt="<? echo $data->teamp()?>">

Is there an easier way to do this? I need tho change this, because I want to create a thumb for this files.

Thanks for the help.