<style>
  .preview-image {
    height: 200px;
  }
</style>

<td><a href="{{ item.get_absolute_url }}" data-toggle="popover" data-placement="right" data-content="<img class='preview-image' src='{{ item.pictures.first.img.url }}' alt='{{ item.part_number }}'>">{{ item.name }}</a></td>

<script type="text/javascript">
  $(document).ready(function(){
    $('[data-toggle="popover"]').popover({
        trigger : 'hover',
        html: true
    });
});
</script>