Yes, Its work easily.
Move all admin controllers to Admin namespace then add following code to your application bootstrap:
    // Loader, registering namespaces
    $loader = new Phalcon\Loader();
    $loader->registerNamespaces(array(
        'Admin'   => YOUR_APP_PATH . '/controllers/admin',
    ));
    $loader->register();
and add these lines to your router settings:
        $admin = new \Phalcon\Mvc\Router\Group(array(
            'namespace'     => 'admin',
            'controller' => 'index',
            'action'     => 'index'
        ));
        $panel->setPrefix('/panel');
        $router->add('/admin(/:controller(/:action(/:params)?)?)?', array(
            'namespace'     => 'admin',
            'controller' => 2,
            'action'     => 4,
            'params'     => 6,
        ))->setName('admin');
        $router->mount($admin);
        return $router;