How to use an alias name in the current select

Hello

I have :
SELECT
t_orders_articles.k_id AS k_id
,t_orders_articles.quantity AS order_qty
,(SELECT sum(quantity) FROM t_deliveries_articles WHERE
article_id = t_orders_articles.k_id) AS delivery_qty
, (t_orders_articles.quantity - delivery_qty) AS qty
FROM t_orders_articles
......;

But it's not working I receive the error :
ERROR : The column delivery_qty does not exist.

How can I make that without having 2 select call ?

Regards
Guy