| Liu Zhiqiang,Hu Zhihui,Dai Jianrong.Application of dynamic jaw technique in helical tomotherapy for mid-esophageal carcinoma[J].Chinese Journal of Radiological Medicine and Protection,2019,39(1):63-67 |
| Application of dynamic jaw technique in helical tomotherapy for mid-esophageal carcinoma |
| Received:June 20, 2018 |
| DOI：10.3760/cma.j.issn.0254-5098.2019.01.012 |
| KeyWords:Dynamic jaw Mid-Esophageal carcinoma Helical tomotherapy |
| FundProject:国家重大研发计划项目（2016YFC0904600） |
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| Abstract:: |
| Objective To evaluate the feasibility of replacing the fixed jaw 2.5 cm mode with dynamic jaw 5.0 cm for mid-esophageal cancer after the upgrade of helical tomotherapy (TOMO).Methods A total of 10 patients with locally advanced esophageal cancer were planned with radical intent using 2.5 cm fixed jaw (FJ2.5), 2.5 cm dynamic jaw (DJ2.5) and 5.0 cm dynamic jaw (DJ 5.0) modes respectively on TOMO. Dose conformity index (CI), dose homogeneity index (HI) and dose to OARs were analyzed to evaluate the plan quality. Treatment time and monitor units were used to assess efficiency.Results CI and HI met clinical requirement for all plans. DJ5.0 plans showed significant improvement over FJ2.5 plans in terms of V5 and mean dose to lungs, the V5, V10 and mean dose to normal tissues (t=9.751, 4.163, 11.840, 10.321, 3.745, P<0.05). DJ2.5 plans were superior to DJ5.0 plans in the aspects of the V30, V40 and mean dose to heart, the V20 and mean dose to normal tissues (-2.454, -3.275, -4.192, -6.435, -4.139, -6.431, P<0.05). Compared with DJ2.5 plans, the V5, V20, V30 and mean dose to lungs, the V40 and mean dose to heart, maximum dose to cord and cord PRV, the V5, V10, V20 and mean dose to normal tissues of FJ2.5 plans were worse (t=8.289, 6.142, 3.137, 8.895, 3.597, 4.565, 3.782, 5.429, 16.421, 12.496, 8.286, 11.933, P<0.05). The beam-on time of DJ5.0 plans was significantly reduced by 43.9% and 42.8% compared with FJ2.5 and DJ2.5 plans respectively, and the machine monitor unit was reduced by 42.8% and 43.8% respectively.Conclusions The dynamic jaw of 5.0 cm technique is recommended for treatment of mid-esophageal cancer for sake of plan quality and efficiency. It does not only shorten the treatment time and improve radiation efficiency compared with fixed and dynamic jaw of 2.5 cm technique, but also provides a dosimetric advantage in terms of lung and normal tissue sparing in comparison with fixed jaw of 2.5 cm. When only improving plan quality is concerned, the dynamic jaw of 2.5 cm technique is more recommendable. |
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