upload image in admin form

gistfile1.txt

            // Save photo
            if(isset($_FILES['image']['campaign_thumbnail']) && $_FILES['image']['campaign_thumbnail'] != '') {
                try {
                    $uploader = new Varien_File_Uploader('image');

                    $uploader->setAllowedExtensions(array('jpg','jpeg','gif','png'));
                    $uploader->setAllowRenameFiles(false);
                    $uploader->setFilesDispersion(false);

                    // Set media as the upload dir
                    $media_path  = Mage::getBaseDir('media') . DS . 'nwtcampaigns' . DS;

                    // Upload the image
                    $uploader->save($media_path, $_FILES['image']['campaign_thumbnail']);

                    $data['image'] = $media_path . $_FILES['image']['campaign_thumbnail'];

                }
                catch (Exception $e) {
                    print_r($e);
                    die;
                }
            }
            else {
                if(isset($data['image']['delete']) && $data['image']['delete'] == 1) {
                    $data['image'] = '';
                }
                else {
                    unset($data['image']);
                }
            }
            if(isset($data['image'])) $model->setImage($data['image']);