| Wang Haiyang,Liu Shuaipeng,Huo Jia,Han Bin,Wang Fangna,Jia Fei,Liu Lele,Kong Fanyang,Pei Yuntong,Hu Jinyan,Guo Yuexin.Impact factors of dose distribution in the abutment area duing total body irradiation with helical tomotherapy[J].Chinese Journal of Radiological Medicine and Protection,2018,38(12):923-927 |
| Impact factors of dose distribution in the abutment area duing total body irradiation with helical tomotherapy |
| Received:May 29, 2018 |
| DOI：10.3760/cma.j.issn.0254-5098.2018.12.008 |
| KeyWords:Helical tomotherapy Total body irradiation Field width Pitch Target gap distance |
| FundProject:河南省科技计划项目（182102310578） |
| Author Name | Affiliation | | Wang Haiyang | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | Liu Shuaipeng | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | Huo Jia | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | Han Bin | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | Wang Fangna | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | Jia Fei | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | Liu Lele | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | Kong Fanyang | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | Pei Yuntong | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | Hu Jinyan | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | Guo Yuexin | Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China |
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| Abstract:: |
| Objective To investigate the optimal distance between upper and lower target volumes and their correlated planning parameters by analyzing the dose distribution in the abutment regions during total body irradiation (TBI) using helical tomotherapy.Methods A total of 10 patients with acute leukemia and with a height around 120 cm were enrolled. All patients were scanned by a Siemens simulation computerized tomography (CT) at a slice thickness of 5 mm. A lead wire was placed 10.0 cm above the patella as a marker of the separation boundary for the upper and lower target volumes. The delineations of target volumes and organs at risk (OARs) were performed in the Varian Eclipse 13.5 workstation with targets shrunk beyond the separation boundary at different distances. After contours and CT images were transferred to HT workstation, treatment plans were designed with different field width (FW, 5.0 cm/2.5 cm/1.0 cm) and pitch values (0.430/0.287) at a modulation factor of 1.8. All the plans were optimized with a dose calculation grid of 0.195 cm×0.195 cm and identical planning parameters. The correlation between treatment planning parameters and targets shrunk distances were investigated by analyzing the dose distributions in the abutment area.Results The study demonstrated that the dose distributions in the abutment area were influenced only by the field width parameters:when the gap distance between the upper and lower targets was 5.0 cm, the optimal FW is 5.0 cm; Similarly when the gap distances were 2.0 cm and 1.0 cm, and the optimal FW 2.5 cm and 1.0 cm, respectively. In another words, the dose distribution of the abutment region was optimal when the target gap distance was equal to FW. Pitch values did not affect the quality of dose distribution in the abutment region and the overall treatment time ratio. Overall treatment time was inversely related to the FW.Conclusions Consistent target distance and FW is helpful to improve the dose homogeneity in the abutment area during TBI with HT. Appropriate planning parameters is critical to balance the treatment efficacy and efficiency. |
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