| Li Longxing,Gao Yan,Chen Hongtao,et al.Optimization of immobilization and positioning methods in hypofractionated stereotactic radiotherapy for brain metastases[J].Chinese Journal of Radiological Medicine and Protection,2024,44(7):587-593 |
| Optimization of immobilization and positioning methods in hypofractionated stereotactic radiotherapy for brain metastases |
| Received:August 18, 2023 |
| DOI：10.3760/cma.j.cn112271-20230818-00053 |
| KeyWords:Brain metastasis Stereotactic radiotherapy Optical surface monitoring system (OSMS) Open face thermoplastic mask Setup error |
| FundProject:广东省医学科学技术研究基金(B2021395);吴阶平医学基金(320.6750.19088-3) |
| Author Name | Affiliation | E-mail | | Li Longxing | Department of Radiation Oncology, Shenzhen People's Hospital, Second Clinical Medical College of Ji'nan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen 518020, China | | | Gao Yan | Department of Radiation Oncology, Shenzhen People's Hospital, Second Clinical Medical College of Ji'nan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen 518020, China | gaoyan12062006＠126.com | | Chen Hongtao | Department of Radiation Oncology, Shenzhen People's Hospital, Second Clinical Medical College of Ji'nan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen 518020, China | | | Li Zihuang | Department of Radiation Oncology, Shenzhen People's Hospital, Second Clinical Medical College of Ji'nan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen 518020, China | | | Shi Yabin | Department of Radiation Oncology, Shenzhen People's Hospital, Second Clinical Medical College of Ji'nan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen 518020, China | |
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| Abstract:: |
| Objective To compare translational and rotational setup errors between immobilization with open masks combined with positioning with the optical surface monitoring system (OSMS) and immobilization with full masks combined with positioning with laser lights and mask markers, find the advantages of open masks combined with OSMS in hypofractionated stereotactic radiotherapy (HSRT) for brain metastases, and calculate planning target volume (PTV) expansions with different immobilization and positioning method for patients with brain metastases. Methods The setup data of 55 patients with brain metastases who received HSRT were analyzed retrospectively. According to immobilization and positioning method, the patients were divided into group A (OSMS + open masks), group B1 (full head-neck-shoulders masks + polyurethane foam cushions), and group B2 (full head-neck-shoulders masks + standard headrests). Positioning was directed by automatic couch motion in OSMS in group A and by laser lights and mask markers in groups B1 and B2. Cone beam computed tomography (CBCT) scans were registered using the bone registration method to obtain setup errors in six directions (x, y, z, roll, pitch, yaw). PTV expansions were calculated according to the van Herk formula. Results A total of 288 sets of CBCT registration data were acquired. Among three groups, group A showed the smallest mean setup errors and 3D vector error, which were (0.47±0.33) mm, (0.49±0.31) mm, (0.44±0.31) mm, (0.42±0.32)°, (0.48±0.31)°, (0.42±0.22)°, and (0.90±0.39) mm, respectively. Group A differed significantly from group B1 and group B2 in the errors at all directions (P ＜ 0.05) except for the yaw direction compared with group B1 (P ＞ 0.05). Group A had no setup error ≥2 mm in translational directions or ≥2° in rotational directions. Group B1 showed significantly smaller setup errors in the y, z, and yaw directions and 3D vector error than group B2 (P ＜ 0.05). In group A, PTV expansions in three directions (x, y, and z) were 1.32, 1.19, and 1.22 mm, respectively, which were smaller than those of the other two groups. Conclusions In HSRT for patient with brain metastases, compared with full head-neck-shoulders masks combined with laser lights and mask markers, open masks combined with OSMS can significantly improve setup precision in six directions and reduce repeated setup and PTV expansions, which shows promise for clinical application. |
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