PATIENT CHARACTERISTICS: Age: 3 and over Performance status: Karnofsky 50-100% Hematopoietic: Absolute neutrophil count at least 1,000/mm3 Platelet count at least 100,000/mm3 Hepatic: AST less than 1.5 times upper limit of normal (ULN) Alkaline phosphatase less than 1.5 times ULN Renal: Creatinine less than 1.2 mg/dL Other: No allergy to iodine Not pregnant or nursing