Palladium-103 plaque radiation therapy for retinal angioma

Plaque radiation has been used in the treatment of angiomas of the choroid, retina, and vasoproliferative tumors of the retina. Herein, is presented the novel use of palladium-103 (¹⁰³Pd) plaque radiation as primary treatment for retinal angioma.

Two patients presented with solitary peripheral retinal angiomas. Both initially progressed on observation and failed subsequent argon laser photocoagulation. Pre-treatment comparative dosimetry was performed to evaluate the available radiation sources palladium-103 (¹⁰³Pd), iodine-125 (¹²⁵I), and yttrium-90 (⁹⁰Y) for an equivalent tumor apex dose). Yttrium-90 plaque therapy offered the most favorable, measured intraocular dose distribution to the fovea, optic disc and lens for both patients. However, informed consent led to a patient preference for ¹⁰³Pd, due to its prior and more long-term follow-up after irradiation of choroidal hemangiomas, melanoma, and retinoblastoma. Each was treated to ¹⁰³Pd plaque apical doses of 50 and 60 Gray (Gy) over a 7-day period. Doses to fovea were very low at 1.3 and 1.7 Gy respectively. Both angiomas regressed over 1-year observation as evidenced by decreased tumor size, with resolution of retinal exudates, overlying retinal hemorrhage, and a localized retinal detachment. Vision was unchanged.

¹⁰³Pd plaque brachytherapy was utilized to treat two peripheral retinal vascular angiomas. Calculated doses to fovea and optic disc suggest no risk of radiation maculopathy or optic neuropathy. ¹⁰³Pd plaque brachytherapy was found to control tumor growth and reverse their exudation resulting in preservation of vision.