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Stereotactic targeting and dose verification for age‐related macular degeneration
Author(s) -
Gertner Michael,
Chell Erik,
Pan KuangHung,
Hansen Steve,
Kaiser Peter K.,
Moshfeghi Darius M.
Publication year - 2010
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3291648
Subject(s) - macular degeneration , retina , materials science , optics , optic nerve , fovea centralis , reproducibility , dosimetry , biomedical engineering , medicine , nuclear medicine , ophthalmology , physics , foveal , retinal , mathematics , statistics
Purpose: Validation of the targeting and dose delivery of the IRay™ low voltage age‐related macular degeneration treatment system. Methods: Ten human cadaver eyes were obtained for this study and mounted in the IRay™ system. Using gel and vacuum, an I‐Guide™ immobilization device was coupled to the eyes and radiochromic film was affixed to the posterior aspect of the globes. Three narrow x‐ray beams were delivered through the pars plana to overlap on the predicted nominal fovea. A needle was placed through the center of the film's beam spot and into the eye to register the film and the inner retina. The process was performed three times for each of the ten eyes (30 simulated treatments; 90 individual beams). The globes were dissected to assess the targeting accuracy by measuring the distances from the needles to the fovea. The dose to the fovea was calculated from the radiochromic film. Results: X‐ray targeting on the retina averaged 0.6 ± 0.4 mm from the fovea. Repeated treatments on the same eye showed a reproducibility of 0.4 ± 0.4 mm . The optic nerve was safely avoided, with the 90% isodose edge of the beam spot between 0.4 and 2.6 mm from the edge of the optic disk. Measured dose matched that prescribed. Conclusions: This study provides confidence that the IRay™, with an average accuracy of 0.6 mm and a precision of 0.4 mm, can reliably treat most AMD lesions centered on the fovea. With the exception of motion, all sources of error are included.