Make the image itself a label for the radio button, so you can click the image to select it.

htdocs/theme/default/templates/form/artefactchooser-element.tpl

@@ -4,6 +4,6 @@
             {else}<input type="checkbox" id="{$elementname}_{$artefact->id}" name="{$elementname}[{$artefact->id}]"{if $value && in_array($artefact->id, $value)} checked="checked"{/if}>
             <input type="hidden" name="{$elementname}_onpage[]" value="{$artefact->id}">
             {/if}</td>
-        <td style="width: 22px;"><img src="{$artefact->icon|escape}" alt="*"></td>
+        <td style="width: 22px;"><label for="{$elementname}_{$artefact->id}"><img src="{$artefact->icon|escape}" alt="*"></label></td>
         <th><label for="{$elementname}_{$artefact->id}">{if $artefact->description}{$artefact->description|escape}{else}{$artefact->title|escape}{/if}</label></th>
     </tr>