New radiotherapeutic techniques in nuclear ophthalmology

Various aspects of radiotherapeutic techniques used in treating ocular tumors are discussed. Previous and current "standard" modalities are briefly reviewed, including beta and gamma emitters, 60Co, 125I, and charged particles. In particular, emphasis is placed upon techniques under development that use biomolecules to physiologically target radioactive or stable isotopes to ocular melanoma. These procedures include 35S-thiouracil, 127I-deoxyuridine in conjunction with irradiation with photons from 145Sm, neutron capture therapy, and various combinations of the above. Thiouracil shows particular promise because of its incorporation during malanin synthesis in growing melanoma. Radiosensitization and stimulation of Auger cascades via introduction of iodine in DNA followed by irradiation with activating photons of appropriate energy (from 145Sm) has been shown to be effective in vitro. Various molecules may be used to transport boron to ocular melanoma, including thiouracil, thus allowing selective irradiation of tumor cells via 10B (n, alpha) 7Li reaction.