| LU Jie,MA Yi-dong,YIN Yong,MA Chang-sheng,LIU Bo,ZHANG Gui-fang,HU Man,BAI Tong.Dosimetric study of planning of intensity-modulated radiotherapy based on deformable registration for patients with nasopharyngeal carcinoma during the course[J].Chinese Journal of Radiological Medicine and Protection,2011,31(5):575-578 |
| Dosimetric study of planning of intensity-modulated radiotherapy based on deformable registration for patients with nasopharyngeal carcinoma during the course |
| Received:December 16, 2010 |
| DOI：10.3760/cma.j.issn.0254-5098.2011.05.018 |
| KeyWords:Deformable registration Nasopharyngeal carcinoma Dosimetry |
| FundProject: |
| Author Name | Affiliation | | LU Jie | Shandong Provincial Key Laboratory of Radiooncology, Department of Radiation Oncology Physics of Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan 250117,China | | MA Yi-dong | Shandong Provincial Key Laboratory of Radiooncology, Department of Radiation Oncology Physics of Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan 250117,China | | YIN Yong | Shandong Provincial Key Laboratory of Radiooncology, Department of Radiation Oncology Physics of Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan 250117,China | | MA Chang-sheng | Shandong Provincial Key Laboratory of Radiooncology, Department of Radiation Oncology Physics of Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan 250117,China | | LIU Bo | Shandong Provincial Key Laboratory of Radiooncology, Department of Radiation Oncology Physics of Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan 250117,China | | ZHANG Gui-fang | Shandong Provincial Key Laboratory of Radiooncology, Department of Radiation Oncology Physics of Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan 250117,China | | HU Man | Shandong Provincial Key Laboratory of Radiooncology, Department of Radiation Oncology Physics of Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan 250117,China | | BAI Tong | Shandong Provincial Key Laboratory of Radiooncology, Department of Radiation Oncology Physics of Shandong Cancer Hospital, Shandong Academy of Medical Sciences, Jinan 250117,China |
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| Abstract:: |
| Objective To evaluate the anatomic changes and dosimetric variations of patients with nasopharyngeal carcinoma (NPC) during the course of simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) by comparison of the dosimetric differences with or without replanning. Methods Twelve cases with NPC treated with SIB-IMRT underwent repeated CT scans after 20-25 fractions of the initiation of therapy. The original treatment plan (Plan1) based on the first CT scan (CT1) and the second IMRT plan (Plan 2) based on the second CT scan (CT2) were calculated with an inverse planning system (Pinnacle3, Philips Medical System). In addition, the hybrid IMRT plan, Plan1 (CT2), was generated by deformable registration with MIMVISTA software, and the doses in Plan 1 (CT1) and Plan 2 (CT2) were accumulated based on CT2. The dosimetric differences were compared among the Plan 1 (CT1), Plan 1 (CT2) and Plan 1+2(CT2). Results Compared with CT1, the mean volumes of the right and left parotid glands in the CT2 were significantly smaller by (24.6±11.9)% and (35.1±20.1)%, respectively. Compared with Plan 1 (CT1), the dose received by 95% of the target ( D95) to PGTV, PTV1 and PTV2, and mean dose (Dmean) to PGTV, and PTV2 were all significantly lower in the Plan 1 (CT2), indicating that the doses to targets decreased without replanning. With repeated CT and replanning after 25 fractions as shown in Plan 1+2(CT2), the doses to targets would be improved. The doses to normal tissue were increased without replanning, although no statistical significance was observed. In 5 of 12 cases, the doses to the spinal cord and brainstem exceeded the constraint without replanning, while the corresponding values decreased with replanning. Conclusions During the course of IMRT for cases with NPC, the volumes of the targets and parotid glands decrease significantly. Mid-treatment CT scanning and replanning should be recommended to ensure adequate doses to the targets and safe doses to the normal tissues. |
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