PRIMARY OBJECTIVES: I. To determine the maximum tolerated dose (MTD) and associated toxicities of intravenous yttrium-90 (90Y) chimeric T84.66 (cT84.66) anti-carcinoembryonic antigen (CEA) antibody targeted radiotherapy delivered after carboplatin/paclitaxel or cisplatin/etoposide and external beam radiotherapy in patients with CEA positive stage III unresectable or medically inoperable non-small cell lung cancer.