| Ma Pan,Li Yongbao,Li Minghui,et al.Design of a semi-spherical applicator for intraoperative radiotherapy with a linear accelerator and assessment of its dosemetric characteristics based on Monte Carlo simulation[J].Chinese Journal of Radiological Medicine and Protection,2020,40(11):868-872 |
| Design of a semi-spherical applicator for intraoperative radiotherapy with a linear accelerator and assessment of its dosemetric characteristics based on Monte Carlo simulation |
| Received:May 12, 2020 |
| DOI：10.3760/cma.j.issn.0254-5098.2020.11.010 |
| KeyWords:Semi-spherical applicator Intraoperative electron beam radiotherapy Intracranial metastatic tumor |
| FundProject:2020-09-30 |
| Author Name | Affiliation | E-mail | | Ma Pan | Department of Radiation Oncology, National Cancer Center, National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China | | | Li Yongbao | Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China | | | Li Minghui | Department of Radiation Oncology, National Cancer Center, National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China | | | Niu Chuanmeng | Department of Radiation Oncology, National Cancer Center, National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China | | | Xie Xin | Department of Radiation Oncology, National Cancer Center, National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China | | | Ma Min | Department of Radiation Oncology, National Cancer Center, National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China | | | Liu Bo | Image Processing Center, Beihang University, Beijing 100083, China | | | Zhou Fugen | Image Processing Center, Beihang University, Beijing 100083, China | | | Dai Jianrong | Department of Radiation Oncology, National Cancer Center, National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China | dai_jianrong@cicams.ac.cn |
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| Abstract:: |
| Objective To design a semi-spherical applicator for delivery of semi-spherical dose distributions and assess its dosemetric characteristics. Methods The applicator was designed in the following way. First, the scattering angle and dose rate of the electron beam having passed through a series of scattering foils of different thicknesses were calculated to determine the thickness of the scattering foil. And then, a series of location model was designed, and the variances of the mean electron energy on the surface of these models were calculated to determine the foil location. Finally, the relationship between the geometric characteristics of the layer and the surface dose on the applicator was established to design the modulator. Monte Carlo (MC) codes EGSnrc/BEAMnrc and EGS4/DOSXYZ were employed to model the head of the Mobetron, the location model, the layer, the semi-spherical applicator, and to calculate the dose distributions. Results A semi-spherical applicator was designed for electron beam of energy 12 MeV, which consisted of a 2.5 cm diametre cylindrical collimator with 0.5 cm thick wall made of 0.3 cm thick steel and 0.2 cm thick water equivalent material (WEM), a 0.14 cm-thick foil made of tansgen, and a 2.5 cm diametre hollow semi-sphere containing a crescent modulator made of WEM. The dose rate was about 160 cGy/min, and the depth of the 50% isodose curve was 0.85 cm. Conclutions We designed and performed a MC simulation of a semi-spherical applicator to deliver a semi-spherical dose distribution from a high energy electron beam. |
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