Palladium-103 versus Iodine-125: Which is Better for your Eye?
Original research just published in the Journal of Radiation Oncology, compares the relative, clinical intraocular dose distribution for palladium-103 versus iodine-125 seeds in gold-plaques for ophthalmic radiation therapy.
The authors examined 319 consecutive uveal melanomas treated between 2006 and 2012. When prescribed an equivalent tumor-apex dose, the use of palladium-103 was associated with a mean 41.9 % lower radiation dose to the opposite eye wall.
Futher subgroup analysis of smallertumors showed greater dose reductions to normal ocular structures than larger tumors. Location of the tumor and thus plaque location also affected the intraocular dose distribution. For example, the use of palladium-103 offered dose reductions to the macular fovea, optic nerve, and opposite eye wall that were significantly greater for iris and ciliary body melanomas compared to those in the back of the eye.
Dr. Finger notes, that The 2014 American Brachytherapy Society consensus guidelines also recommend that centers compare available radiation sources for dose to normal ocular structures and use that information to help decide on which radiation source to use for their patients.
In conclusion, preoperative comparative radiation dosimetry was performed for a large number of patients with uveal melanoma. It influenced the decision to use palladium-103 or iodine-125. It also offered an opportunity for radiation sparing of critical vision-related intraocular structures.
The authors examined 319 consecutive uveal melanomas treated between 2006 and 2012. When prescribed an equivalent tumor-apex dose, the use of palladium-103 was associated with a mean 41.9 % lower radiation dose to the opposite eye wall.
Futher subgroup analysis of smallertumors showed greater dose reductions to normal ocular structures than larger tumors. Location of the tumor and thus plaque location also affected the intraocular dose distribution. For example, the use of palladium-103 offered dose reductions to the macular fovea, optic nerve, and opposite eye wall that were significantly greater for iris and ciliary body melanomas compared to those in the back of the eye.
Dr. Finger notes, that The 2014 American Brachytherapy Society consensus guidelines also recommend that centers compare available radiation sources for dose to normal ocular structures and use that information to help decide on which radiation source to use for their patients.
In conclusion, preoperative comparative radiation dosimetry was performed for a large number of patients with uveal melanoma. It influenced the decision to use palladium-103 or iodine-125. It also offered an opportunity for radiation sparing of critical vision-related intraocular structures.
The conclusions of this study are supported by the following independent research:
Radiobiology for eye plaque brachytherapy and evaluation of implant duration and radionuclide choice using an objective function. Gagne NL, Leonard KL, Rivard MJ. Medical Physics 2012;39(6):3332-3342.
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