Purpose:
To determine whether the computed dosimetry of a new ophthalmic radiation plaque, EP917, when compared to the standard COMS plaque, 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 using Bebig "Plaque Simulator" treatment-planning software, both for COMS plaques and EP917 plaques using 125Iodine. Dose distributions were calculated for a prescription of 85 Gray (Gy) to the tumor apex. Total doses to the sclera, optic disc, opposite retina, lens, and macula were obtained. The differences in measures between the two groups were calculated using standard parametric methods.
Results:
When compared with the COMS plaque, the mean number of radiation seeds utilized was fewer by 1.94 [p<0.001, 95% CI -2.8 to -1.06] and the total strength of radiation sources was also reduced by 17.74 U (air kerma units) [p<0.001, 95% CI -20.16 to -15.32] with the EP917 plaques. 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 versus the COMS plaques (Table 1).
Conclusions:
EP917 plaques provide for an overall less radiation exposure to critical vision structures than COMS treatment plaques, while still delivering the same total therapeutic dose to the tumor.
Keywords: melanoma • radiation therapy • tumors