Management of orbital tumours with adjuvant iodine brachytherapy using "inverted" plaques

Purpose To describe our experience in using "inverted" iodine plaques as adjuvant treatment after resection of orbital tumours. Methods Between 1999 and 2007, three patients (ages 17‐48 years) underwent resection of an lacrimal gland tumour followed by application of an "inverted" iodine plaque manage any microscopic infiltration, i.e. a gold plaque carrying iodine‐125 seeds on its convex rather than concave surface. In a fourth instance, the seeds were placed on the convex surface of a ruthenium rather than a gold plaque to manage an eye with a late extraocular recurrence of an irradiated uveal melanoma following resection of the extension. Results The diameter of the plaque was 20 mm. It was sutured to the sclera so that when the eye was in primary position the lacrimal fossa was targeted. When the eye moved, the irradiated volume naturally enlarged. A 40‐56 Gy dose was calculated to the depth of 10 mm, and the dose at 5 mm was then calculated as 80‐134 Gy. Treatment time was 59‐154 hours. In one case, the iodine seeds were placed asymmetrically to limit radiation damage to the eyelid skin. In two patients, transient erythema of the upper eyelid developed, which resolved in a few months time. In case of the extraocular melanoma, dose was the same. Recurrent tumours have not developed. Conclusion An "inverted" iodine plaque is one option for adjuvant irradiation of the orbit which shields the eye from radiation damage.