ref; zen-cart v1.3.6

How can I use PHP to load an image by adding PHP code in the product desctriptiuon text box.
example;

<?php
$image_name = "t.gif";

include("/includes/CUSTOM/display_image.php");

//------------------------
display_image.php file

<img src= <?php echo $image_name ?> width="100" height="95">


?> // end of code

Appreciate any Idea's ...
Thank U...