Dosimetric benefit of a new ophthalmic radiation plaque.
OBJECTIVE
To determine whether the computed dosimetry of a new ophthalmic plaque, EP917, when compared with the standard Collaborative Ocular Melanoma Study (COMS) plaques, could reduce radiation exposure to vision critical structures of the eye.


METHODS
One hundred consecutive patients with uveal melanoma treated with COMS radiation plaques between 2007 and 2010 were included in this study. These treatment plans were generated with the use of Bebig Plaque Simulator treatment-planning software, both for COMS plaques and for EP917 plaques using I-125. Dose distributions were calculated for a prescription of 85 Gy to the tumor apex. Doses to the optic disc, opposite retina, lens, and macula were obtained, and differences between the 2 groups were analyzed by standard parametric methods.


RESULTS
When compared with the COMS plaques, the EP917 plaques used fewer radiation seeds by an average difference of 1.94 (P<.001; 95% confidence interval [CI], -2.8 to -1.06) and required less total strength of radiation sources by an average of 17.74 U (air kerma units) (P<.001; 95% CI, -20.16 to -15.32). The total radiation doses delivered to the optic disc, opposite retina, and macula were significantly less by 4.57 Gy, 0.50 Gy, and 11.18 Gy, respectively, with the EP917 plaques vs the COMS plaques.


CONCLUSIONS
EP917 plaques deliver less overall radiation exposure to critical vision structures than COMS treatment plaques while still delivering the same total therapeutic dose to the tumor.
Department of Radiation Oncology, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, Ohio, USA. marwahg2@ccf.org
Gaurav
G
Marwaha
Allan
A
Wilkinson
James
J
Bena
Roger
R
Macklis
Arun D
AD
Singh
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D006801:Humans; D007908:Lens, Crystalline / Q000528:radiation effects; D008266:Macula Lutea / Q000528:radiation effects; D008545:Melanoma / Q000532:radiotherapy*; D008875:Middle Aged; D009898:Optic Disk / Q000528:radiation effects; D058958:Organs at Risk / Q000528:radiation effects*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D012160:Retina / Q000528:radiation effects; D012984:Software; D014604:Uveal Neoplasms / Q000532:radiotherapy*; D000098943:Uveal Melanoma