| Liu Lele,Ma Yangguang,Li Guowen,et al.A comparison of the dosimetric effects of systematic MLC leaf position errors on flattening filter and flattening filter-free IMRT for nasopharyngeal carcinoma[J].Chinese Journal of Radiological Medicine and Protection,2015,35(11):835-838 |
| A comparison of the dosimetric effects of systematic MLC leaf position errors on flattening filter and flattening filter-free IMRT for nasopharyngeal carcinoma |
| Received:February 13, 2015 |
| DOI：10.3760/cma.j.issn.0254-5098.2015.11.008 |
| KeyWords:Flattening filter-free Multi leaf collimator Position error Intensity radiotherapy Dosimetry |
| FundProject: |
| Author Name | Affiliation | E-mail | | Liu Lele | Department of Radiation Oncology, First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | | Ma Yangguang | Department of Radiation Oncology, First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | | Li Guowen | Department of Radiation Oncology, First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | | | Guo Yuexin | Department of Radiation Oncology, First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China | 13838081115@126.com |
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| Abstract:: |
| Objective To compare the dosimetric effects of systematic MLC leaf position errors on flattening filter(FF) and flattening filter-free(FFF) IMRT for nasopharyngeal carcinoma(NPC).Methods In totaly of ten patients with NPC were enrolled in the current study. FF IMRT and FFF IMRT plans were designed for each patient, and in-house software was developed to modify the corresponding MLC files. Briefly, three kinds of systematic MLC error presented with 0.5 and 1 mm magnitudes error were simulated. The modified MLC files were re-imported into IMRT plans for dose recalculation, and differences in the dosimetry trends between FF-IMRT and FFF-IMRT plans were analyzed using a dose-volume histogram.Results Upon closed MLC, the average changes in D95% of PTV and Dmean of parotid glands in FFF-IMRT plans were more sensitive than in FF-IMRT plans(t=3.298-4.793, P<0.05). Otherwise, when MLC are shifted in the same direction, changes in D95% of PTV, Dmean of PGTV, PTV as well as Dmean of left parotid gland in FFF-IMRT plans were also more sensitive(t=2.372-6.844, P<0.05), whereas average changes in Dmean of right parotid gland presented with less sensitivity(t=-4.049,-3.378, P<0.05).Conclusions For out-of-field or large organs, FFF-IMRT plans are more sensitive to leaf position error than FF-IMRT plans. |
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