Evaluating the dose to the contralateral breast when using a dynamic wedge versus a regular wedge

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Secondary breast cancers in the contralateral breast are a significant concern after primary breast irradiation.
• Scatter radiation is a major contributor to secondary breast cancer induction, influenced by treatment techniques like wedges.

Purpose of the Study:

• To compare the peripheral radiation dose to the contralateral breast from regular wedges, dynamic wedges, and open fields.
• To evaluate the efficacy of dynamic wedges in reducing scatter radiation compared to traditional methods.

Main Methods:

• Measurements of peripheral dose outside the radiation field were conducted using patients, solid water, and a Rando phantom.
• Data were collected using ion chambers, thermoluminescent dosimeters (TLDs), diodes, and films on a Varian 2300CD linear accelerator.
• Comparison of dose distributions for regular wedges, dynamic wedges, and open field techniques, particularly for medial tangential fields.

Main Results:

• Dynamic wedges resulted in peripheral doses close to open fields.
• Regular wedges, especially for medial tangential fields, delivered significantly higher doses to the contralateral breast compared to open fields.
• Dynamic wedges demonstrated a significantly lower peripheral dose compared to regular wedges.

Conclusions:

• Dynamic wedges are recommended over regular wedges for medial tangential fields to minimize contralateral breast dose.
• Implementing dynamic wedges can reduce the risk of secondary breast cancer induction from scatter radiation.
• This study provides evidence for optimizing breast irradiation techniques to improve patient safety.