Analyzing the Impact of BMI on Breast Cancer Setup Errors in Prone Position Radiation Therapy: A Comparison of Manual and Automated Image Matching

In radiation therapy, the precision of patient positioning is crucial, particularly when using the prone position to minimize exposure to organs at risk (OAR). This investigation explores the effect of Body Mass Index (BMI) on setup errors in prone positioning, emphasizing the distinction between manual and automated image matching techniques. Data from 27 patients with normal weight and 88 overweight patients, treated from February to November 2023 with the VARIAN iX Linear Accelerator and assessed through weekly On-Board Imaging (OBI), were analyzed. Both manual and automated matching methods were utilized to evaluate setup error (Laterolateral(X axis), Craniocaudal (Y axis),Anterioposterior (Z axis), Yaw)deviations, correlating these with the patients' BMI.

The analysis demonstrated that in automated matching, patients with a higher BMI showed mean displacement values of 0.192±0.2296 cm (P<0.05) in the X axis and 0.118±0.3590 degree (P<0.05) in the Yaw axis, significantly higher than those with a normal BMI. Manual matching reinforced this finding, with a notable increase in displacement for higher BMI patients in the X axis, averaging 0.344±0.2828 cm (P<0.05). These results reveal that patients with higher BMI face greater challenges in maintaining precise positioning during prone radiation therapy, potentially affecting treatment precision.

This study shows the necessity for customized positioning strategies in prone radiation therapy for patients with higher BMI. By addressing these positioning challenges, it is possible to improve treatment precision and ensure more effective radiation therapy outcomes.