Modified COMS Plaques for {sup 125}I and {sup 103}Pd Iris Melanoma Brachytherapy

Journal Article · Mon Nov 15 04:00:00 EST 2010 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.12.002· OSTI ID:21451166

Furutani, Keith M; Pulido, Jose S; Stafford, Scott L ^[1]; Rogers, D W.O. ^[2]

---

1. Mayo Clinic College of Medicine, Rochester, MN (United States)
2. Ottawa Carleton Institute of Physics, Carleton University, Ottawa, ON (Canada)

Purpose: Novel plaques are used to treat iris melanoma at the Mayo Clinic Rochester. The plaques are a modification of the Collaborative Ocular Melanoma Study (COMS) 22 mm plaque design with a gold alloy backing, outer lip, and silicone polymer insert. An inner lip surrounds a 10 mm diameter cutout region at the plaque center. Plaques span 360{sup o}, 270{sup o}, and 180{sup o} arcs. This article describes dosimetry for these plaques and others used in the treatment of anterior eye melanomas. Methods and Materials: The EGSnrc user-code BrachyDose is used to perform Monte Carlo simulations. Plaques and seeds are fully modeled. Three-dimensional dose distributions for different plaque models, TG-43 calculations, and {sup 125}I (model 6711) and {sup 103}Pd (model 200) seeds are compared via depth-dose curves, tabulation of doses at points of interest, and isodose contours. Results: Doses at points of interest differ by up to 70% from TG-43 calculations. The inner lip reduces corneal doses. Matching plaque arc length to tumor extent reduces doses to eye regions outside the treatment area. Maintaining the same prescription dose, {sup 103}Pd offers lower doses to critical structures than {sup 125}I, with the exception of the sclera adjacent to the plaque. Conclusion: The Mayo Clinic plaques offer several advantages for anterior eye tumor treatments. Doses to regions outside the treatment area are significantly reduced. Doses differ considerably from TG-43 predictions, illustrating the importance of complete Monte Carlo simulations. Calculations take a few minutes on a single CPU, making BrachyDose sufficiently fast for routine clinical treatment planning.

• OSTI ID: 21451166
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 4 Vol. 78; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BETA DECAY RADIOISOTOPES
BODY
BRACHYTHERAPY
CALCULATION METHODS
CARCINOMAS
COMPUTERIZED SIMULATION
DAYS LIVING RADIOISOTOPES
DEPTH DOSE DISTRIBUTIONS
DISEASES
DOSES
ELECTRON CAPTURE RADIOISOTOPES
EPITHELIOMAS
EVEN-ODD NUCLEI
EYES
FACE
HEAD
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODINE 125
IODINE ISOTOPES
ISOTOPES
MEDICINE
MELANOMAS
MONTE CARLO METHOD
NEOPLASMS
NUCLEAR MEDICINE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
ORGANS
PALLADIUM 103
PALLADIUM ISOTOPES
PLANNING
POLYMERS
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
RADIOISOTOPES
RADIOLOGY
RADIOTHERAPY
SENSE ORGANS
SILICONES
SILOXANES
SIMULATION
SPATIAL DOSE DISTRIBUTIONS
THERAPY