Почитайте http://intmedical.ru/forum/topic/155-%D0%BA%D0%BE%D0%BD%D0%B8%D0%BA%D0%BE%D1%82%D0%BE%D0%BC%D0%B8%D1%8F-%D0%B2-%D0%B4%D0%BE%D0%BC%D0%B0%D1%88%D0%BD%D0%B8%D1%85-%D1%83%D1%81%D0%BB%D0%BE%D0%B2%D0%B8%D1%8F%D1%85/