| Qiu Jianjian,Zhang Xiaoying,Mo Fan,et al.A customized vacuum cushion for immobilization in the radiotherapy of pelvic malignancies[J].Chinese Journal of Radiological Medicine and Protection,2017,37(11):838-842 |
| A customized vacuum cushion for immobilization in the radiotherapy of pelvic malignancies |
| Received:February 17, 2017 Revised:June 09, 2017 |
| DOI：10.3760/cma.j.issn.0254-5098.2017.11.007 |
| KeyWords:Immobilization Radiotherapy Pelvic neoplasm Set-up error Dosimetry |
| FundProject: |
| Author Name | Affiliation | E-mail | | Qiu Jianjian | Department of Radiation Oncology, Fudan University Affiliated Huadong Hospital, Shanghai 200040, China | | | Zhang Xiaoying | Department of Radiation Oncology, Fudan University Affiliated Huadong Hospital, Shanghai 200040, China | | | Mo Fan | Department of Radiation Oncology, Fudan University Affiliated Huadong Hospital, Shanghai 200040, China | | | Zhang Libo | Department of Radiation Oncology, Fudan University Affiliated Huadong Hospital, Shanghai 200040, China | | | Zheng Xiangpeng | Department of Radiation Oncology, Fudan University Affiliated Huadong Hospital, Shanghai 200040, China | zhengxp@fudan.edu.cn |
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| Abstract:: |
| Objective To evaluate the performance of a customized vacuum-form body immobilization method in the radiotherapy of pelvic malignancies by comparing it with conventional approaches, thus to improve immobilization accuracy in the radiotherapy of pelvic malignancies. MethodsA total of 66 patients with pelvic malignancies were enrolled in this study. These patients were divided into three groups according to three immobilization approaches:radiotherapy board (Group N), conventional vacuum cushion (Group V), and a customized vacuum cushion specifically for pelvic immobilization (Group New-V). Setup deviations of these immobilizations were comparatively evaluated by translational and rotational errors during intra-fractional measurements. Results The average translational setup errors in vertical(x), longitudinal(y), lateral(z) and rotational error r were (0.35±0.37), (0.21±0.22), (0.29±0.28) cm and (0.70±0.65)° for Group New-V; (0.44±0.43), (0.31±0.62), (0.45±0.60) cm and (1.25±1.00)° for Group N; (0.38±0.36), (0.27±0.25), (0.32±0.29) cm and (1.09±0.77)° for Group V, respectively. Significant differences were observed in r direction among these three method (F=7.859,P<0.05).Group New-V with customized cushion showed the least standard deviations in four directions and the least setup error in r direction compared with the other two method (F=3.166,P<0.05). Reconstructed dose distribution based on the isocenter shift result ed from setup errors revealed that Group New-V showed the least deviations in the minimum and mean dose and of the planning target volume (PTV) before and after isocenter shift(F=8.018, P<0.05). Conclusions The customized vacuum cushion provided best immobilization and dosimetric advantage. It helps to optimize the immobilization accuracy and improve the clinic outcome potentially. |
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