Study on the Clinical Applicability of Different Immobilization Techniques in Helical
Tomotherapy for Patients with Breast Cancer
ZHANG Lia,LI Zhongweia,WU Dia,YANG Peib
a. Department of Radiological Physics and Technology丨 b. Department of Third Head and Neck Radiotherapy,
Hunan Cancer Hospital, Changsha Hunan 410013, China
Abstract:Objective To study the difference of set-up errors and clinical applicability of two immobilization techniques including
integrated bracket combined with thermoplastic membrane and breast bracket for breast cancer patients in radiotherapy based on
megavoltage computed tomography (MVCT) image guidance system. Methods Thirty patients with breast cancer who underwent
helical tomotherapy from August 2019 to March 2020 in Hunan cancer hospital were included in this study and randomly divided
into thermoplastic membrane group (15 cases) and breast bracket group (15 cases). Patients in thermoplastic membrane group were
immobilized with integrated bracket combined with thermoplastic membrane, while the breast bracket group was fixed with breast
bracket. After positioning, spiral homologous MVCT image guidance system was used to verify the image-guided set-up errors,
obtain the set-up errors in left-right (x), superior-inferior (y), anterior-posterior (z) , rotation (R) directions, and record the positioning
time of two groups. The mean value of the set-up errors of two groups was calculated, and then the mean was grouped for analysis
of variance and independent samples t-test. The outspread value of inter-fractional set up error of the planning target volume (PTV)
was calculated. Results The errors of the thermoplastic membrane group and the breast bracket group in the direction of x, y, z, R
were as follows: (2.03±0.92) mm and (2.87±0.84) mm丨 (1.84±0.73) mm and (2.38±1.30) mm丨 (2.08±0.73) mm and (3.33±1.61) mm丨
(0.30±0.19) ° and (0.54 ± 0.29) °. There were significant differences between the two groups in the three directions of x, z and
R丨 there was no significant difference in y-axis. The extension values of inter-fractional set-up error of CTV to PTV were 2.88 and
4.52 mm, 2.99 and 3.9 mm, 2.69 and 4.63 mm respectively. The time of single positioning was (4.2±2.1) min and (6.3±3.3) min
respectively. Conclusion In the helical tomotherapy for breast cancer, the positioning error of the integrated bracket combined with
thermoplastic membrane immobilization technique is smaller than that of the breast bracket immobilization technique, which can
improve the treatment accuracy and positioning efficiency, and has better clinical applicability and is worthy of popularization.
张利a,李忠伟a,吴迪a,杨锫b. 不同体位固定技术在乳腺癌螺旋断层放射治疗中的临床适用性研究[J]. 中国医疗设备, 2021, 36(11): 55-58.
ZHANG Lia,LI Zhongweia,WU Dia,YANG Peib. Study on the Clinical Applicability of Different Immobilization Techniques in Helical
Tomotherapy for Patients with Breast Cancer. China Medical Devices, 2021, 36(11): 55-58.