Eye sparing in high energy X ray beams

Area of Science:

• Radiation oncology
• Ophthalmology
• Medical physics

Background:

• Cancer treatment for the nasopharynx and antrum frequently involves radiation to nearby eye tissues.
• Directing high-energy X-ray beams through the eye is one therapeutic approach.
• Protecting the eye from radiation while ensuring adequate tumor dosage is a clinical challenge.

Purpose of the Study:

• To investigate a method for reducing radiation entrance dose to the eye during cancer treatment.
• To evaluate the effectiveness of build-up materials with varying densities in protecting ocular tissues.
• To optimize radiation delivery for head and neck cancers adjacent to the eye.

Main Methods:

• Utilizing an anterior high-energy X-ray beam directed through the eye towards the tumor.
• Employing build-up material placed on the skin with a tunnel created to the eye.
• Comparing the effects of tissue-like versus higher-density build-up materials on radiation dose distribution.
• Analyzing scattered radiation within the tunnel and its impact on superficial eye layers.

Main Results:

• Tissue-like build-up materials resulted in significant scattered radiation from tunnel walls, diminishing build-up benefits.
• Higher-density build-up materials substantially reduced the dose to the superficial eye layers.
• The dose reduction approached the theoretical limits set by open beam characteristics with dense materials.

Conclusions:

• Higher-density build-up materials are effective in minimizing ocular radiation exposure during head and neck cancer treatment.
• This technique allows for high radiation doses to the tumor while protecting the uninvolved eye.
• The method has demonstrated successful clinical application for eight years, indicating its efficacy and safety.