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P.T. Finger, A. Szechter, M.A. Astrahan; Seed–Guide Inserts Standardize Seed Positions Within Eye Plaques: Clinical Experience . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2263.
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© ARVO (1962-2015); The Authors (2016-present)
To utilize a "seed–guide" insert to standardize eye plaque radiation therapy for patients with choroidal melanoma.
160 patients with choroidal melanoma were treated with palladium–103 plaque radiation therapy. Plaque construction involved the re–usable gold "seed–guide" insert to standardize seed locations. Seed positions were based on the COMS–type silastic insert. From a dosimetric perspective, the space formerly occupied by the silastic carrier is now assumed to be water equivalent. This is desirable because it eliminates the dosimetric uncertainties related to the atomic composition of silastic insert. Water equivalency will allow some fluorescent x–rays from the gold backing to reach the eye. These very low energy x–rays had been absorbed by the silastic. Loaded with 125I seeds, this new plaque produces dose distributions that are almost the same as the original COMS–silastic plaque. Dose distributions calculated for a modified plaque loaded with 103Pd seeds show that dose to healthy ocular structures distal to the tumor apex can be reduced compared to 125I.
In alls cases, the inserts were sized to fit within standard gold COMS plaques. The new inserts facilitated seed placement, subsequent dosimetry, and preoperative plaque sterilization. In contrast to silastic seed carriers, the "seed–guide" inserts allowed for more reproducible positioning of the seeds [at the inner plaque–surface] and removed the dose–reducing silastic from between the seeds and the sclera. Unlike the COMS–type insert, the use of the new inserts eliminated the chance of a silastic–related plaque offset from the scleral surface. In this series the seed–guide inserts functioned properly and did not shift from their glued position attached to the inner surface of the plaque.
The gold "seed–guide" insert was easy to use, standardized seed positioning, facilitated plaque dosimetry, allowed preoperative chemical sterilization and was re–usable. No complications were related to the use of the "seed–guide" insert.
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