Three-dimensional conformal breast irradiation in the prone position

Area of Science:

• Radiation Oncology
• Medical Physics
• Surgical Oncology

Background:

• Adjuvant radiotherapy after conservative breast surgery aims to reduce local recurrence.
• Conventional supine positioning may lead to significant irradiation of lung and cardiac tissues.
• Optimizing radiotherapy planning is crucial for minimizing treatment-related toxicity.

Purpose of the Study:

• To compare the efficacy of prone versus supine positioning for adjuvant radiotherapy planning in breast cancer patients.
• To evaluate the impact of positioning on radiation dose delivered to the lungs and heart.
• To identify patient subgroups that may benefit most from prone positioning.

Main Methods:

• Three-dimensional conformal radiotherapy planning was performed for five patients in both supine and prone positions.
• Patients had undergone conservative breast surgery for early-stage breast cancer (T1N0M0 or T1N1M0).
• Dose-volume histograms were analyzed to quantify radiation doses to organs at risk.

Main Results:

• Mean ipsilateral lung irradiation dose was significantly lower in the prone position (1.4 Gy) compared to the supine position (8.3 Gy) (P = 0.043).
• Contralateral lung irradiation was also significantly reduced in the prone position (0.3 Gy vs. 1.3 Gy) (P = 0.043).
• Cardiac doses showed a trend towards reduction in the prone position (3.0 Gy vs. 4.6 Gy, P = 0.079).

Conclusions:

• Prone position radiotherapy planning significantly reduces radiation dose to lung tissue compared to the supine position.
• Large-breasted women appear to gain the most benefit from prone positioning.
• Prone positioning is a simple, effective alternative for breast irradiation, potentially lowering pulmonary side effects.