OUTLINE: This is an open label, multicenter study. Arm I: Patients receive radiotherapy once a day, 5 days a week, for 6 weeks. Gadolinium texaphyrin IV is administered every other day within 2-5 hours prior to radiotherapy. Patients are evaluated at 1 month, and if no more than 1 of 3 patients experiences unacceptable toxicity, 3 patients are entered on the imaging portion of the study. Once arm I has successfully entered 3 patients with acceptable toxicity profiles and 3 patients in the imaging portion of the study, patient enrollment begins for arm II. Arm II: Cohorts of 3-9 patients receive radiotherapy as in arm I and escalating doses of gadolinium texaphyrin IV administered within 2-5 hours prior to each radiation dose. The maximum tolerated dose (MTD) of gadolinium texaphyrin is defined as the dose at which no more than one third of the patients experience dose limiting toxicity. Arm III: Patients experiencing dose limiting toxicity in arm II requiring dose reduction below predetermined once a day limit receive gadolinium every other day, with radiotherapy as in arm II. The MTD is defined as in arm II. Arm IV: An additional 3 patients are enrolled at the MTD and enter the imaging portion of the study. Patients are followed for 1 month after final radiation therapy.