Department of Radiation Oncology, Xiamen Cancer Hospital, The First Affiliated Hospital of Xiamen University, Xiamen, PR China.
PLoS One. 2018 Sep 5;13(9):e0202628. doi: 10.1371/journal.pone.0202628. eCollection 2018.
For whole esophagus and T-shaped field radiotherapy using intensity modulated radiotherapy (IMRT) technique in advanced esophageal cancer, lower absorbed doses to lung and heart remains a challenge. The aim of this study was to investigate the dosimetric superiority in IMRT plans with jaw tracking technique for whole esophagus radiotherapy.
Thirty-two patients with esophageal cancer were subjected to IMRT treatment plans using Eclipse treatment planning system. For every patient, four different plans were generated with six gantry angles: six large fields IMRT plans with fixed jaw (6F-IMRT), six large fields IMRT plans with jaw tracking technique (6F-IMRT-T), twelve small fields IMRT plans with fixed jaw (12F-IMRT), and twelve small fields IMRT plans with jaw tracking technique (12F-IMRT-T). Dosimetric evaluation was assessed for all plans.
For every technique, there were no differences in planning target volume (PTV) coverage and conformity. 6F-IMRT-T plans could significantly reduce lung irradiation with 7.9% (P<0.001) reduction in V5lung and 2.5% (P<0.001) reduction in V20 lung respectively compared to 6F-IMRT plans. 12F-IMRT-T plans resulted in superior plans compared to 12-IMRT plans with a reduction of 2.9% (P<0.001) in V5lung and 0.9% (P<0.001) in V20 lung, respectively. For heart irradiation, 6F-IMRT-T and 12F-IMRT-T plans were slightly superior to 6F-IMRT and 12-IMRT plans respectively with a reduction of 1.1 Gy and 0.5 Gy in the respective mean doses.
By the use of jaw tracking technique, the IMRT plans resulted in further lung and heart sparing compared to fixed jaw plans for radiotherapy in esophageal cancer.
对于采用调强放疗（IMRT）技术的晚期食管癌全食管和 T 形野放疗，降低肺和心脏的吸收剂量仍然是一个挑战。本研究的目的是研究全食管放疗中使用咬合跟踪技术的 IMRT 计划的剂量学优势。
32 例食管癌患者接受了 Eclipse 治疗计划系统的 IMRT 治疗计划。对于每个患者，使用六个机架角度生成了四个不同的计划：六个大野 IMRT 计划，使用固定架（6F-IMRT）；六个大野 IMRT 计划，使用咬合跟踪技术（6F-IMRT-T）；十二个小野 IMRT 计划，使用固定架（12F-IMRT）；十二个小野 IMRT 计划，使用咬合跟踪技术（12F-IMRT-T）。对所有计划进行了剂量学评估。
对于每种技术，计划靶区（PTV）覆盖和适形度都没有差异。与 6F-IMRT 计划相比，6F-IMRT-T 计划可显著降低肺照射剂量，V5 肺分别减少 7.9%（P<0.001）和 V20 肺减少 2.5%（P<0.001）。与 12F-IMRT 计划相比，12F-IMRT-T 计划的结果更好，V5 肺分别减少 2.9%（P<0.001）和 V20 肺减少 0.9%（P<0.001）。对于心脏照射，6F-IMRT-T 和 12F-IMRT-T 计划分别比 6F-IMRT 和 12F-IMRT 计划略有优势，平均剂量分别减少 1.1Gy 和 0.5Gy。
通过使用咬合跟踪技术，与使用固定架的计划相比，IMRT 计划可进一步降低食管癌放疗中的肺和心脏照射剂量。
