What type to upload image within theme options?

If using image radio buttons, define a directory path here is code. I hope its going work.

$imagepath =  get_template_directory_uri() . '/images/';

    $options = array();

    $options[] = array( "name" => __('Logo', 'prothemeus'),
                        "desc" => __('Upload your logo', 'prothemeus'),
                        "id" => "pt_logo",
                        "type" => "upload");