You can heal yourself with your bandages a little, use medkits when your health gets pretty low. Eat food to keep your health up. Also, Army & Scientific medkits reduce radiation.
Pretty much, do all those things while running back to a trader. Sometimes random stalkers will have vodka you can trade for, too. Also, some artifacts reduce radiation, see if you have one of those.
Other than that, reload a save from awhile ago. In stalker, it's a pretty good idea to keep two relatively up-to-date saves (alternate saving to two save files) as stalker is pretty unforgiving.