Application of double-isocenter and fixed-jaw technology in radiotherapy for bilateral breast cancer(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2019年第4期
- Page:
- 373-378
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Application of double-isocenter and fixed-jaw technology in radiotherapy for bilateral breast cancer
- Author(s):
- ZHANG Lei; LI Pu; YANG Yiwei; WENG Denghu; FANG Min; SHAO Kainan; ZHENG Shiming
- Key Laboratory of Tumor Radiotherapy, Department of Radiation Physics, Zhejiang Cancer Hospital, Hangzhou 310022, China
- Keywords:
- ; Keywords: bilateral breast cancer; double-isocenter; fixed-jaw technology; volumetric modulated arc therapy; static intensity-modulated radiotherapy
- PACS:
- R811.1；R737.9；R312
- DOI:
- DOI:10.3969/j.issn.1005-202X.2019.04.001
- Abstract:
- Abstract: Objective To apply double-isocenter and fixed-jaw technology for the design of volumetric modulated arc therapy (VMAT) and static intensity-modulated radiotherapy (sIMRT) plans for bilateral breast cancer and evaluate the dosimetric results of the two plans, so as to discuss the feasibility of double-isocenter and fixed-jaw technology in radiotherapy for bilateral breast cancer. Methods The clinical data of 8 patients with confirmed bilateral breast cancer were retrospective analyzed. Based on Trilogy accelerator parameters, 2 fixed-field radiotherapy plans, namely double-isocenter VMAT (D-VMAT) and double-isocenter sIMRT (D-sIMRT), were designed on RayStation v4.5 system. The planning target volume (PTV) was irradiated with a prescribed dose of 5 000 cGy in 25 fractions. At least 95% of bilateral breast target areas, namely PTV-L and PTV-R, were covered with prescribed dose. The dose-volume histogram and the Clincal goal tool of treatment planning system were used to compare the target dose distribution, the conformity index and homogeneity index of PTV, and the dosimetric characteristics of organs-at-risk, such as heart, lungs, liver and spinal cord. Results Both of two radiotherapy plans satisfied the treatment criteria. The bilateral breast target areas were irradiated by prescribed dose and the doses of organs-at-risk were within the limits determined by the clinical physicists. D-VMAT was superior to D-sIMRT in the homogeneity index and conformity index of PTV (P<0.05). No statistical differences were found in the V20 of heart, the V5 and Dmean of liver and the Dmax of spinal cord between two plans. However, the V5, V20, V30 of lungs and mean lung dose were significantly reduced in D-VMAT as compared with D-sIMRT [47.9%±4.6% vs 42.2%±3.9%, 22.9%±6.7% vs 17.5%±4.3%, 15.7%±5.8% vs 11.7%±3.6%, (1 222.5±246.7) cGy vs (1 009.5±161.3) cGy; P=0.001, 0.0021, 0.031, 0.009］. Moreover, compared with D-sIMRT, D-VMAT decreased the mean dose of heart (P<0.05) and increased monitor units (1 177±311 vs 908±130, P=0.036). Conclusion The radiotherapy plan using double-isocenter and fixed-jaw technology meets the requirements of radiotherapy for bilateral breast cancer. Meanwhile, D-VMAT not only achieves better homogeneity index and conformity index of target areas, but also reduces the radiation-induced injuries to heart and lung and increase the efficiency of treatment.
Last Update: 2019-04-22