A method for producing uniform dose distributions in the junction regions of large hinge angle electron fields

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Abutting electron fields in radiation therapy present planning challenges.
• Large hinge angles between electron fields exacerbate issues, creating adjacent high and low dose regions.

Purpose of the Study:

• To present a novel technique using a compensated superficial x-ray (SXR) field to manage junctioning problems between electron fields.
• To evaluate the efficacy of this technique in achieving a uniform dose distribution at field junctions.

Main Methods:

• Developed and applied a compensated superficial x-ray (SXR) field technique for electron field junctions.
• Selected SXR beam parameters and designed a compensator to complement adjacent electron fields.
• Utilized the technique in a clinical case for treating squamous cell carcinoma of the forehead/scalp.

Main Results:

• The compensated SXR field effectively eliminated low-dose zones in the junction region.
• High-dose zones were reduced to 110% of the prescribed dose.
• In the specific clinical case, bone attenuation mitigated potential high-dose areas from SXR.

Conclusions:

• The compensated SXR field technique provides uniform dose distribution up to 3 cm depth.
• This method offers a valuable addition to managing complex electron field junctioning scenarios in radiation therapy.