Radiation Therapy Plus Gadolinium Texaphyrin in Treating Patients With Cancer of the Pancreas That Cannot Be Removed by Surgery

DISEASE CHARACTERISTICS: Histologically confirmed locally advanced, unresectable pancreatic or periampullary adenocarcinoma Patients may have evidence of hepatic or other intra-abdominal or systemic metastases if they have dominant symptomatology from the locally unresectable component of disease Prior treatment with 1 chemotherapy regimen required Palliative bypass procedures without resection allowed Bidimensionally measurable disease on CT or MRI scan PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 60-100% Life expectancy: Not specified Hematopoietic: WBC at least 3,000/mm3 Absolute neutrophil count at least 1,500/mm3 Platelet count at least 150,000/mm3 Hemoglobin at least 8.5 g/dL No history of G6PD deficiency Hepatic: SGOT or SGPT less than 2 times upper limit of normal (ULN) Alkaline phosphatase less than 2 times ULN Bilirubin no greater than 2.0 mg/dL (elevated values must be falling or stable for at least 1 week prior to therapy) Renal: Creatinine no greater than 2.0 mg/dL (no clinical indication of compromised kidney) Other: Not pregnant or nursing Fertile patients must use effective contraception No second malignancy within the past 5 years, except: Resected superficial nonmelanomatous skin cancer Carcinoma in situ of the cervix No uncontrolled or serious medical conditions No active peptic ulcers No weight loss greater than 5% of ideal body weight within 30 days prior to study No uncontrolled nausea and vomiting No claustrophobia PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy No concurrent experimental biologic therapy Chemotherapy: See Disease Characteristics Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy compromising the delivery of radiation on this study No prior radiotherapy to areas within the planned field of treatment Surgery: At least 4 weeks since prior gastrointestinal surgery Other: At least 4 weeks since prior experimental drugs No other concurrent experimental drugs