Department of Radiation Oncology, University of Arizona, Tucson, AZ 85724-5081, USA.
Radiother Oncol. 2011 Dec;101(3):438-42. doi: 10.1016/j.radonc.2011.07.015. Epub 2011 Sep 9.
To compare the effectiveness of tomotherapy and three-dimensional (3D) conformal radiotherapy to spare normal critical structures (spinal cord, lungs, and ventricles) from excessive radiation in patients with distal esophageal cancers.
A retrospective dosimetric study of nine patients who had advanced gastro-esophageal (GE) junction cancer (7) or thoracic esophageal cancer (2) extending into the distal esophagus. Two plans were created for each of the patients. A three-dimensional plan was constructed with either three (anteroposterior, right posterior oblique, and left posterior oblique) or four (right anterior oblique, left anterior oblique, right posterior oblique, and left posterior oblique) fields. The second plan was for tomotherapy. Doses were 45 Gy to the PTV with an integrated boost of 5 Gy for tomotherapy.
Mean lung dose was respectively 7.4 and 11.8 Gy (p=0.004) for tomotherapy and 3D plans. Corresponding values were 12.4 and 18.3 Gy (p=0.006) for cardiac ventricles. Maximum spinal cord dose was respectively 31.3 and 37.4 Gy (p < 0.007) for tomotherapy and 3D plans. Homogeneity index was two for both groups.
Compared to 3D conformal radiotherapy, tomotherapy decreased significantly the amount of normal tissue irradiated and may reduce treatment toxicity for possible dose escalation in future prospective studies.
比较调强放疗和三维适形放疗对远端食管癌患者的正常关键结构（脊髓、肺和脑室）免受过度辐射的效果。
回顾性分析了 9 例患有胃食管交界部（GE）癌症（7 例）或胸段食管癌（2 例）延伸至远端食管的患者的剂量学资料。为每位患者分别创建了两个计划。三维计划采用三野（前后、右后斜和左后斜）或四野（右前斜、左前斜、右后斜和左后斜）进行构建。第二个计划是调强放疗计划。PTV 给予 45Gy 的剂量，调强放疗的综合加量为 5Gy。
调强放疗组和三维计划组的平均肺剂量分别为 7.4Gy 和 11.8Gy（p=0.004）。相应的心室剂量分别为 12.4Gy 和 18.3Gy（p=0.006）。调强放疗组和三维计划组的最大脊髓剂量分别为 31.3Gy 和 37.4Gy（p<0.007）。两组的均匀性指数均为 2。
与三维适形放疗相比，调强放疗显著减少了正常组织的照射量，并可能降低未来前瞻性研究中可能因剂量递增而产生的治疗毒性。
