Yi Seong Lee
Authors: Yi-Seong Lee and Jeong-Koo Kim Journal: Journal of Associated Medical Sciences Volume and issue: 59(1) Pages: 184–190 Publication year: 2026 Published online: November 27, 2025 Official article page: Journal website DOI: Not assigned Abstract Background: Various techniques and devices are used to immobilize the breast satisfactorily during radiation therapy for breast cancer, and they are adopted and utilized in treatment centers according to their preferences. Objectives: In this study, a breast suit was manufactured using the advantages of thermoplastics used in breast cancer and thoracic radiotherapy, and the breast suit was validated by analyzing the reproducibility of setup errors. Materials and methods: A computed tomography simulator and phantom were used to acquire reference images of a breast suit and a commercial bra, respectively. After acquiring the images in the CBCT system, the setup error reproducibility was analyzed using a Volume View™ 3D image acquisition tool. The image analysis method used automated mode and manual mode, and the validity was evaluated by analyzing the change of setup error reproducibility in the X, Y, and Z axis directions and pitch, roll, and yaw rotation directions of each matched image. Results: The reproducibility of setup errors between the breast suit and the commercial bra ranged from 0.4 mm to 5.6 mm on the X-axis and from 0.3 mm to 5.8 mm on the Y-axis. In contrast, the Z-axis exhibited larger variations, ranging from 0.8 mm to 16.2 mm. Rotational setup errors were all less than 1°, indicating no significant differences. While the breast suit showed comparable setup errors to the commercial bra in the X and Y directions, it demonstrated improved reproducibility along the Z-axis (p = 0.09) and significantly lower rotational errors (p < 0.05). Conclusions: The validity of the reproducibility change of setup errors was confirmed in the X, Y, and Z directions for the breast suit, and valid results were obtained for more stable reproducibility change in the Z-axis direction. Therefore, it is inferred that the breast suit can be used as a fixation device to reduce setup error reproducibility by limiting breast movement.