| TIE Jian,SUN Yan,GONG Jian,HAN Shu-kui,JIANG Fan,WU Hao.Dosimetric study comparing volumetric arc modulation with RapidArc and fixed field dynamic intensity-modulated radiation therapy for breast cancer radiotherapy after breast-conserving surgery[J].Chinese Journal of Radiological Medicine and Protection,2011,31(3):317-321 |
| Dosimetric study comparing volumetric arc modulation with RapidArc and fixed field dynamic intensity-modulated radiation therapy for breast cancer radiotherapy after breast-conserving surgery |
| Received:September 15, 2010 |
| DOI：10.3760/cma.j.issn.0254-5098.2011.03.017 |
| KeyWords:Breast cancer Breast-conserving surgery Intensity modulated radiation therapy Volumetric modulated arc therapy Dosimetry |
| FundProject: |
| Author Name | Affiliation | | TIE Jian | Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education), Department of Radiation Oncology, Peking University School of Oncology, Beijing Cancer Hospital & Institute, Beijing 100142, China | | SUN Yan | Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education), Department of Radiation Oncology, Peking University School of Oncology, Beijing Cancer Hospital & Institute, Beijing 100142, China | | GONG Jian | Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education), Department of Radiation Oncology, Peking University School of Oncology, Beijing Cancer Hospital & Institute, Beijing 100142, China | | HAN Shu-kui | Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education), Department of Radiation Oncology, Peking University School of Oncology, Beijing Cancer Hospital & Institute, Beijing 100142, China | | JIANG Fan | Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education), Department of Radiation Oncology, Peking University School of Oncology, Beijing Cancer Hospital & Institute, Beijing 100142, China | | WU Hao | Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education), Department of Radiation Oncology, Peking University School of Oncology, Beijing Cancer Hospital & Institute, Beijing 100142, China |
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| Abstract:: |
| Objective To compare the dosimetric difference between volumetric arc modulation with RapidArc and fixed field dynamic IMRT for breast cancer radiotherapy after breast-conserving surgery. Methods Twenty patients with early left-sided breast cancer received radiotherapy after breast-conserving surgery. After target definition, treatment planning was performed by RapidArc and two fixed fields dynamic IMRT respectively on the same CT scan. The target dose distribution, homogeneity of the breast, and the irradiation dose and volume for the lungs, heart, and contralateral breast were read in the dose-volume histogram (DVH) and compared between RapidArc and IMRT. The treatment delivery time and monitor units were also compared. Results In comparison with the IMRT planning, the homogeneity of clinical target volume (CTV), the volume proportion of 95% prescribed dose (V95%) was significantly higher by 0.65% in RapidArc (t=5.16, P =0.001),and the V105% and V110% were lower by 10.96% and 1.48 % respectively, however, without statistical significance (t=-2.05, P =0.055 and t=-1.33, P =0.197).The conformal index of planning target volume (PTV) by the RapidArc planning was (0.88±0.02), significantly higher than that by the IMRT planning [(0.74±0.03),t=18.54, P ﹤0.001]. The homogeneity index (HI) of PTV by the RapidArc planning was 1.11±0.01, significantly lower than that by the IMRT planning (1.12±0.02,t=-2.44, P =0.02). There were no significant differences in the maximum dose ( D max) and V20 for the ipsilateral lung between the RapidArc and IMRT planning, but the values of V10, V5, Dmin and Dmean by RapidArc planning were all significantly higher than those by the IMRT planning (all P <0.01). The values of max dose and V30 for the heart were similar by both techniques, but the values of V10 and V5 by the RapidArc planning were significantly higher (by 18% and 50%, respectively). The V5 of the contralateral breast and lung by the RapidArc planning were increased by 9.33% and 3.04% respectively compared to the IMRT planning. The mean MU of the RapidArc was 608 MU, significantly higher than that by the IMRT planning (437 MU,t=10.86, P ﹤0.001). The treatment time by the RapidArc planning was 111.3 s, significantly longer than that by IMRT planning (103.6 s,t=3.57, P =0.002).Conclusions The RapidArc planning improves the dose distribution of CTV and homogeneity of PTV for breast cancer radiotherapy after breast-conserving surgery. However, it significantly enlarges the volume of normal tissues irradiated in low dose areas, prolongs the treatment delivery time, and increases the MU value in comparison with IMRT. |
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