Objective To compare the radiotherapy positioning error and radiation skin response of post-breast conserving radiotherapy patients with breast cancer using breast bracket positioning and thermoplastic membrane double labeling combined with fenestration technology. The feasibility of the positioning method based on thermoplastic-membrane double labeling combined with fenestration technology was also explored.

Methods The clinical data of 83 female patients post-breast conserving radiotherapy for breast cancer after breast-conserving surgery at the Fifth Affiliated Hospital of Zhengzhou University from January 2019 to December 2020 were retrospectively analyzed. The patients were aged (47.5±10.1) years. According to the positioning method, they were divided into breast-bracket group (41 cases) and body-membrane group (42 cases). Two groups of patients underwent positioning verification using a linear accelerator under airborne cone-beam CT before radiotherapy. Evaluated the acute and late radiation skin reactions in enrolled patients according to the standards established by the Radiation Therapy Oncology Group of United States. Intergroup comparison of the positioning error was conducted using the t-test, and intergroup comparison of the counting data was conducted using the chi-square test.

Results Positioning errors in the left and right (X-axis) (2.14±0.19) mm vs. (2.96±0.20) mm, head and foot (Y-axis) (2.49±0.15) mm vs. (3.05±0.16) mm, and abdominal back (Z-axis)(2.41±0.22) mm vs. (3.14±0.19) mm directions of the body-membrane group were significantly lower than those of the breast-bracket group (t=2.98, 2.63, and 2.49, respectively; all P<0.05). When the positioning error was ≤3 mm, the distribution proportion of the body-membrane group in the Y-axis direction was higher than that of the breast-bracket group (72.20% vs. 48.78%; χ²=7.23, P=0.01), when the positioning error was >5 mm, the distribution proportion of body membrane in the X-axis(3.81% vs. 8.78%), Y-axis (8.78% vs. 33.17%), and Z-axis (10.95% vs. 24.88%) groups was lower than that of the breast-bracket group (χ²=4.37, 12.40, and 13.73, respectively; all P<0.05). The incidence of acute radiation skin reaction was significantly different between the two groups (30.95% vs. 53.66%; χ²=4.39, P=0.04).

Conclusions The thermoplastic membrane double labeling combined with fenestration technology reduces the positioning error and alleviates acute radioactive skin reaction. It also has better stability and repeatability, is safer and more reliable, and is easy to operate.