Optic disc dose reduction in ocular brachytherapy using ¹²⁵ I notched COMS plaques: A simulation study based on...

Area of Science:

• Ocular oncology
• Radiation physics
• Medical imaging

Background:

• Collaborative Ocular Melanoma Study (COMS) plaques are standard for ocular brachytherapy.
• Optic disc dose reduction using notched COMS plaques remains underexplored.
• Minimizing optic disc radiation is crucial for preserving vision.

Purpose of the Study:

• To investigate optic disc dose reduction with ¹²⁵I notched COMS plaques.
• To compare dose reduction efficacy against standard ¹²⁵I COMS plaques.
• To provide data for optimizing treatment planning in ocular melanoma.

Main Methods:

• Developed a MATLAB-based brachytherapy dose calculation program using AAPM TG-43U1 formalism.
• Simulated optic disc doses for standard and notched COMS plaques (one or two seeds removed).
• Calculated dose reduction as a function of tumor margin-optic disc distance and basal dimensions for various prescription depths.

Main Results:

• Notched COMS plaques demonstrated significant optic disc dose reduction.
• Five distinct trends in dose reduction were identified, varying with plaque design and tumor geometry.
• Dose reduction increased with greater prescription depths.

Conclusions:

• Notched ¹²⁵I COMS plaques offer a viable strategy for reducing optic disc dose.
• Clinicians can utilize these findings to select appropriate plaque types and prescription depths.
• This can help minimize radiation-induced optic neuropathy in ocular brachytherapy.