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Dosimetric Calculations of a Radioactive Eye Plaque used in Management of Ocular Melanoma Using Monte Carlo Simulations
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P Shokrani   1, Gh Raisali , A Janati |
| 1- , shokrani14@yahoo.com |
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Abstract: (4219 Views) |
| Introduction & Objective: Brachytherapy using I-125 radioactive seeds in removable episcleral plaques (EP) is often used in treatment of ocular malignant melanoma. Some radioactive seeds are fixed in a gold bowl-shaped plaque. The plaque is sutured to the sclera surface corresponding to the base of the intraocular tumor, allowing for a localized radiation dose delivery to the tumor. Minimum target doses as high as 85Gy are directed at malignant tumor. The aim of this study was to develop a Monte Carlo simulation of an ocular plaque in order to calculate the resulting isodose distributions.
Materials & Methods: The MCNP-4C Monte Carlo code is used to simulate the plan of an episcleral plaque treatment. A 20-mm Collaborative Ocular Melanoma Study (COMS) plaque with 3, I-125 seed of model 6711 was used. Resulting dose distributions, including central axis dose and off-axis dose profiles, were calculated in a water phantom with 12mm radius. The calculated dose distributions were compared to the corresponding dose measured by Knuten et al., 2001.
Results: Central axis dose calculations represent a rapid dose fall off, which is an important factor in selection of appropriate eye plaque for management of tumors with known dimension. Calculated off-axis dose profiles show decreased dose uniformity at distances close to the plaque. Increasing of distance from the plaque resulted in increasing of the dose uniformity.
Conclusion: Monte Carlo simulation of eye plaques can be used as a useful tool in process of design, development and treatment planning of ocular radioactive plaques. |
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| Keywords: Brachytherapy, Dosimetric Calculation, Monte Carlo |
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Full-Text [PDF 131 kb]
(996 Downloads)
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Type of Study: Research |
Subject:
Special
Received: 2015/05/30 | Accepted: 2015/05/30 | Published: 2015/05/30
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