PURPOSE: A dosimetry study comparing the use of I-125 vs. Pd-103 radioactive seeds for ophthalmic plaque brachytherapy. METHODS AND MATERIALS: Palladium-103 (Pd-103) seeds in ophthalmic plaques were used to treat 15 patients with intraocular malignant melanoma. Computer-aided simulations were performed to evaluate the intraocular dose distribution of I-125 versus Pd-103 ophthalmic plaques (delivering equivalent apex doses). Seven target points were selected. Starting at the outer scleral surface, four were located along the central axis of the plaque: the 1 mm point (the inner sclera), the 6 mm point, the tumors apex, and the opposite eye wall. We also evaluated the fovea, optic nerve, and the lens because they were considered to be critical structures. RESULTS: These studies demonstrated that the lower energy photons generated by Pd-103 seeds (average 21 KeV) in ophthalmic plaques were more rapidly absorbed in tissue than photons generated by I-125 (average 28 KeV). Therefore, during ophthalmic plaque radiotherapy, Pd-103 photons were found to be more rapidly absorbed within the tumor and less likely to reach most normal ocular structures. On average, the use of Pd-103 decreased the dose to the fovea by 5.7%, to the optic nerve by 8.4%, to the lens by 26%, and to the opposite eye wall by 38.4%. CONCLUSION: Palladium-103 ophthalmic plaque brachytherapy resulted in slightly more irradiation of the tumor and less radiation to most normal ocular structures.
PURPOSE: A dosimetry study comparing the use of I-125 vs. Pd-103 radioactive seeds for ophthalmic plaque brachytherapy. METHODS AND MATERIALS: Palladium-103 (Pd-103) seeds in ophthalmic plaques were used to treat 15 patients with intraocular malignant melanoma. Computer-aided simulations were performed to evaluate the intraocular dose distribution of I-125 versus Pd-103 ophthalmic plaques (delivering equivalent apex doses). Seven target points were selected. Starting at the outer scleral surface, four were located along the central axis of the plaque: the 1 mm point (the inner sclera), the 6 mm point, the tumors apex, and the opposite eye wall. We also evaluated the fovea, optic nerve, and the lens because they were considered to be critical structures. RESULTS: These studies demonstrated that the lower energy photons generated by Pd-103 seeds (average 21 KeV) in ophthalmic plaques were more rapidly absorbed in tissue than photons generated by I-125 (average 28 KeV). Therefore, during ophthalmic plaque radiotherapy, Pd-103 photons were found to be more rapidly absorbed within the tumor and less likely to reach most normal ocular structures. On average, the use of Pd-103 decreased the dose to the fovea by 5.7%, to the optic nerve by 8.4%, to the lens by 26%, and to the opposite eye wall by 38.4%. CONCLUSION:Palladium-103 ophthalmic plaque brachytherapy resulted in slightly more irradiation of the tumor and less radiation to most normal ocular structures.
Authors: Kirtesh R Patel; Roshan S Prabhu; Jeffrey M Switchenko; Mudit Chowdhary; Caroline Craven; Pia Mendoza; Hasan Danish; Hans E Grossniklaus; Thomas M Aaberg; Thomas Aaberg; Sahitya Reddy; Elizabeth Butker; Chris Bergstrom; Ian R Crocker Journal: Brachytherapy Date: 2017-03-03 Impact factor: 2.362
Authors: Hasan Danish; Matthew J Ferris; Ehsan Balagamwala; Jeffrey M Switchenko; Kirtesh R Patel; Maria Choudhary; Caroline Craven; Pia Mendoza; John Suh; Chris Bergstrom; Hans E Grossniklaus; Thomas M Aaberg; Arun Singh; Ian R Crocker; Mohammad K Khan Journal: Melanoma Res Date: 2018-04 Impact factor: 3.599