OBJECTIVES: I. Determine the maximum tolerated dose of gadolinium texaphyrin in patients with locally advanced, unresectable pancreatic or periampullary adenocarcinoma undergoing local regional radiotherapy. II. Determine the toxic effects of gadolinium texaphyrin with concurrent radiotherapy in these patients. III. Correlate estimates of tumor and normal organ gadolinium texaphyrin uptake and retention over time by MRI with plasma/serum levels in these patients.