Individualized positioning for maximum heart protection during breast irradiation

Area of Science:

• Radiation Oncology
• Medical Physics
• Breast Cancer Treatment

Background:

• Prone positioning is recognized for reducing lung radiation dose in breast cancer radiotherapy.
• The impact of prone positioning on cardiac radiation dose remains a subject of debate.
• Individual patient anatomy is crucial for determining optimal treatment positioning.

Purpose of the Study:

• To evaluate the effect of prone versus supine positioning on heart and left anterior descending coronary artery (LAD) radiation doses.
• To identify patient-specific anatomical factors influencing cardiac dose in different positions.
• To develop a model for individualized positioning to maximize heart protection during radiotherapy.

Main Methods:

• Conformal radiotherapy plans were created for 138 left-sided breast cancer patients in both prone and supine positions.
• Radiation doses to the heart and LAD were compared between the two positions.
• Image fusion of CT scans was used to analyze anatomical variations and heart position relative to the chest wall.

Main Results:

• Cardiac and LAD radiation doses varied individually and were significantly correlated with body mass index (BMI).
• Prone positioning can be detrimental if the heart moves closer to the chest wall, increasing dose.
• Median distance between the LAD and chest wall (dmedian) and heart area in the radiation field (Aheart) were identified as key parameters.

Conclusions:

• Individualized positioning is essential for minimizing cardiac dose in breast cancer radiotherapy.
• A validated statistical model incorporating BMI, dmedian, and Aheart enables personalized positioning strategies.
• This approach aims to maximize heart protection by accounting for patient-specific anatomy.