Dosimetric validation of the Theragenics AgX-100® I-125 seed for ROPES eye plaque brachytherapy

  • Claire PagulayanEmail author
  • Soo Min Heng
  • Stephanie Corde
Scientific Paper


With the discontinued distribution of the I-125 Oncura Onco seed (model 6711), the Theragenics AgX100® I-125 seeds were considered as a suitable alternative for eye plaque brachytherapy as their physical properties matched the requirements for use with the ROPES eye plaques. The purpose of this study aims at validating the dosimetry of the AgX-100 loaded ROPES plaques (11 mm diameter, 15 mm diameter with flange, 15 mm diameter with notch, 18 mm diameter) and assess the differences with the discontinued I-125 6711 model. To independently verify the plaque dosimetry, the brachytherapy module of RADCALC® version was commissioned for the new AgX-100 I-125 seed using the published AAPM TG43 data from the literature. Experimental dosimetry verification was performed using EBT3 Gafchromic™ film and TLD-100 micro-cubes in a specially designed Solid Water® phantom. Both RADCALC® and film confirmed the dosimetry calculated by Plaque Simulator (PS) version 6.4.6 The dose calculated by PS agrees with RADCALC® to within 2% for depths of 1–15 mm for the 4 available ROPES plaques. The dosimetric measurements agreed with the calculations of PS for clinically relevant depths (4 mm to 6 mm) within the evaluated uncertainties of 4.7% and 7.2% for EBT3 film and TLDs respectively. The AgX-100 I-125 seed was a suitable replacement for the 6711 I-125 seed. Due to the introduction of the stainless-steel backscatter factor in PS v6.4.6, the department has decided to report both the homogenous dose and heterogeneity corrected dose for each eye plaque patient.


ROPES Eye plaques I-125 seeds Brachytherapy Ocular melanoma 



The authors would like to acknowledge Matthew Newall for his contributions to the figures of this paper.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

This research did not involve any human participants or animal experiments.


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Copyright information

© Australasian College of Physical Scientists and Engineers in Medicine 2019

Authors and Affiliations

  1. 1.Nelune Comprehensive Cancer CentrePrince of Wales HospitalSydneyAustralia

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