permalink open post with other template

Hello,

I want to use one post with a different layout(template)

Beneath my code which I use, when I open the link de layout of the rest of the site is opened also and I want to use a other layout when opening the whole text, what must I do?

<?php
query_posts( ‘cat=4’ );
if (have_posts()) : while (have_posts()) : the_post(); $category = get_the_category(); ?>

<?php the_excerpt(); ?>

” rel=”shadowbox” title=”<?php the_title(); ?>”>Lees het volledige artikel
<?php endwhile; else: ?>
<p><?php _e(‘Sorry, no posts matched your criteria.’); ?></p>
<?php endif; ?>