Reznik Julia, Cicchetti M Giulia, Degaspe Barbara, Fitzgerald T J
University of Massachusetts Memorial Medical Center, Worcester, MA 01655, USA.
Int J Radiat Oncol Biol Phys. 2005 Jan 1;61(1):163-8. doi: 10.1016/j.ijrobp.2004.04.065.
To evaluate the percent of the prescribed radiation dose to the breast delivered to the axillary tissue and to evaluate the volume of the axilla receiving 95% of the prescribed dose with normal and with high tangential fields.
Computed tomographic scan images with 5-mm sections were retrospectively analyzed for 35 patients who had undergone three-dimensional (3D) planning for whole-breast radiation. The axillary nodal region was identified and divided into Levels I to III and Rotter's nodes (RN). Digitally reconstructed radiographs were created, and two plans were developed: (a) the standard clinical opposed tangential irradiation fields and (b) the high-tangential irradiation fields. Axillary coverage was examined by use of dose-volume histograms (DVH), and the average coverage for the four nodal groups was obtained.
The data show that with the standard tangential irradiation fields, the average dose delivered to Levels I, II, III, and RN is 66% (standard deviation, or SD = 13%), 44% (SD = 18%), 31% (SD = 20%), and 70% (SD = 19%) of the prescribed dose, respectively. The coverage increases to 86% (SD = 9%), 71% (SD = 19%), 73% (SD = 17%), and 94% (SD = 8%) of the prescribed dose, respectively, for Levels I, II, III, and RN when the high tangential irradiation fields are used. 51% of Level I, 26% of Level II, and 15% of Level III receive 95% of the prescribed dose with normal tangents. The volume increases to 79%, 51%, and 49% of Levels I, II, and III, respectively, with high tangents.
The tangential fields designed to treat only the breast do not adequately cover the axillary region and, therefore, cannot be relied upon for prophylactic therapy of the axilla. The high tangential irradiation fields increase the dosages received by the axillary region, but the average dosages received by the lower axillary regions are still less than 90% of the prescribed dose.
评估乳腺所接受的处方辐射剂量中传递至腋窝组织的百分比，并评估在使用常规和高切线野时接受95%处方剂量的腋窝体积。
对35例接受全乳放疗三维（3D）计划的患者进行回顾性分析，这些患者的计算机断层扫描图像层厚为5毫米。确定腋窝淋巴结区域并分为Ⅰ至Ⅲ级及罗特淋巴结（RN）。创建数字重建射线照片，并制定两个计划：（a）标准临床对置切线照射野和（b）高切线照射野。通过剂量体积直方图（DVH）检查腋窝覆盖情况，并获得四个淋巴结组的平均覆盖情况。
数据显示，使用标准切线照射野时，Ⅰ、Ⅱ、Ⅲ级及RN所接受的平均剂量分别为处方剂量的66%（标准差，SD = 13%）、44%（SD = 18%）、31%（SD = 20%）和70%（SD = 19%）。使用高切线照射野时，Ⅰ、Ⅱ、Ⅲ级及RN所接受的剂量分别增加至处方剂量的86%（SD = 9%）、71%（SD = 19%）、73%（SD = 17%）和94%（SD = 8%）。常规切线时，Ⅰ级的51%、Ⅱ级的26%和Ⅲ级的15%接受95%的处方剂量。高切线时，Ⅰ、Ⅱ、Ⅲ级的体积分别增加至79%、51%和49%。
仅用于治疗乳腺的切线野不能充分覆盖腋窝区域，因此不能依靠其对腋窝进行预防性治疗。高切线照射野增加了腋窝区域所接受的剂量，但腋窝下部区域所接受的平均剂量仍低于处方剂量的90%。
