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Optimization of 1 2 5 I ophthalmic plaque brachytherapy
Author(s) -
Astrahan Melvin A.,
Luxton Gary,
Jozsef Gabor,
Liggett Peter E.,
Petrovich Zbigniew
Publication year - 1990
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 - 10.1118/1.596585
Subject(s) - brachytherapy , dosimetry , nuclear medicine , radiation therapy , medicine , medical imaging , electromagnetic shielding , limiting , radiology , physics , quantum mechanics , mechanical engineering , engineering
Episcleral plaques containing 1 2 5 I sources are often used in the treatment of ocular melanoma. Within four years post‐treatment, however, the majority of patients experience some visual loss due to radiation retinopathy. The high incidence of late complications suggests that careful treatment optimization may lead to improved outcome. The goal of optimization would be to reduce the magnitude of vision‐limiting complications without compromising tumor control. We have developed a three‐dimensional computer model for ophthalmic plaque therapy which permits us to explore the potential of various optimization strategies. One simple strategy which shows promise is to maximize the ratio of dose to the tumor apex ( T ) compared to dose to the macula ( M ). By modifying the parameters of source location, activity distribution, source orientation, and shielding we find that the calculated T : M ratio can be varied by a factor of 2 for a common plaque design and posterior tumor location. Margins and dose to the tumor volume remain essentially unchanged.