Image Attachment Cropping

I have been fiddling around with this code:

<?php
// Set the post content to a variable
$szPostContent = $post->post_content;

// Define the pattern to search
$szSearchPattern = '~<img [^\>]*\ />~';

// Run preg_match_all to grab all the images and save the results in $aPics
preg_match_all( $szSearchPattern, $szPostContent, $aPics );

// Count the results
 $iNumberOfPics = count($aPics[0]);

// Check to see if we have at least 1 image
if ( $iNumberOfPics > 0 )
{

     // Now here you would do whatever you need to do with the images
     // For this example I'm just going to echo them
     for ( $i=0; $i < $iNumberOfPics ; $i++ )
     {
          echo $aPics[0][$i];
     };

};

Basically what this does is pull the first image attachment from a post and echos it to the font page. However I can’t seem to figure out how to work this in conjunction with phpThumb.

The reason I want to use phpThumb is because WordPress is limited to cropping an image to the thumbnail size only, medium, and full sizes can’t be cropped.