Legacy Devers Eye Institute
Plaque radiotherapy or brachytherapy is one of the most common treatment modalities for the treatment of ocular melanomas. Brachytherapy is a type of radiation therapy in which seeds, ribbons, or capsules that contain a radiation source are placed in the body, in or near the tumor. It is often used to treat cancers of the head and neck, breast, cervix, prostate, and eye.
In the case of ocular melanomas, the radioactive seeds are embedded in a saucer-shaped disc/plaque, which has an inner, concave radioactive surface and an outer, convex protective shield. Every radioactive plaque is custom made to the dimensions (e.g thickness and diameter) of each tumor.
The plaque radiotherapy treatment involves:
- Radioactive plaque placement: A 45-minute operation under general anesthesia, during which the plaque is placed against the wall of the eye directly over the tumor. The plaque is secured in place by non-absorbable sutures. If possible, a biopsy of the tumor is performed immediately before the radioactive plaque is sutured to the eye. The radioactive plaque usually stays sutured on the eye for 5-7 days during which the radiation treats the tumor cells. This radiation does not travel beyond the eye so there is no risk of hair loss or other general problems.
- Radioactive plaque removal: A second, 25-minute operation under general or local anesthesia is performed. The plaque is removed between five and seven days later, once the appropriate dose of radiation has been delivered. There is no radiation once the plaque is removed.
Additional notes for plaque radiotherapy:
- There are several radioactive isotopes that have been used for plaque brachytherapy of choroidal melanomas. The most common isotope is radioactive iodine, but ruthenium or palladium are also popular in other parts of the world. Every isotope has a different profile in the amount and radiation profile that emits.
- Iodine plaques can generally treat tumors up to 9 mm thick (albeit giving a higher dose of radiation to normal ocular structures).