Finger's "slotted" eye plaque for radiation therapy: treatment of juxtapapillary and circumpapillary intraocular tumours.
OBJECTIVE
To create "slotted eye plaques" for the treatment of juxtapapillary and circumpapillary intraocular tumours.


METHODS
Eye plaques were altered such that 8 mm-wide slots (variable length) were created to accommodate the orbital portion of the optic nerve. Thus, as the nerve entered the slot, the plaque's posterior margin extended beyond the optic disc. Radioactive seeds were affixed around the slot, surrounding the juxtapapillary and posterior tumour margins.


RESULTS
As proof of principle, three patients with choroidal melanomas that encircled or were in contact with the optic disc (considered untreatable with a notched eye plaque) were considered to be initial candidates for slotted-plaque radiotherapy. Preoperative three-dimensional C-scan imaging of their optic nerve sheath diameters insured that they would fit in the slotted plaque. Intraoperative ultrasound imaging was used to confirm proper plaque placement. Radiation dosimetry modelling showed that all tumour tissue received a minimum of 85 Gy (despite the gap created by the slot). With relatively short-term follow-up, there has been no evidence of ocular ischaemia, tumour growth or complications attributable to the use of slotted-plaque radiation therapy.


CONCLUSIONS
Slotted plaques accommodate the retrobulbar optic nerve into the device and thereby shift the treatment zone to improve coverage of both juxtapapillary and circumpapillary intraocular tumours.
Finger
Paul T
PT
The New York Eye Cancer Centre, 115 East 61st Street, New York City, NY 10065, USA. pfinger@eyecancer.com
D000328:Adult; D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D002830:Choroid Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008545:Melanoma / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D009898:Optic Disk / Q000033:anatomy & histology; D009900:Optic Nerve / Q000033:anatomy & histology; D018579:Patient Selection; D011874:Radiometry / Q000379:methods; D014463:Ultrasonography