Objective To investigate the relationship of radiation dose with the volume and late toxicity of the sternocleidomastoid muscle ( SM) in patients with nasopharyngeal carcinoma. Methods SM was divided into upper part and lower part based on the lower edge of cricoid cartilage. Patients were divided into three groups according to the prescribed dose for clinical target volume at the lower neck ( CTV2 ) ( 0, 54,60 Gy) . The dosimetric parameters included Dmean , V66 , and V60 for the upper, lower, and whole SM. SM was delineated and the volume was calculated on computed tomography images in the treatment planning system before and at 6, 12, and 18 months after treatment. The anteroposterior and transversal diameters of SM at C3⁃C4 , C4⁃C5 , C5⁃C6 , and C6⁃C7 levels were measured and recorded. Late toxicity of neck skin and SM was evaluated according to the Common Terminology Criteria for Adverse Events V4 .0 criteria. Between⁃group comparison was made by t⁃test or Kruskal⁃Wallis non⁃parametric test. Between⁃group comparison of the sample rate was made by one⁃way analysis of variance. The correlation analysis was made by Spearman correlation. Results There were significant difference in SM volume between the three time points after treatment ( P=0. 000) . At 12 or 18 months after treatment, the volume of SM wasignificantly reduced ( P=0. 000,0. 000);the reduction in SM volume was significantly correlated with V66 of the SM and the upper SM ( P=0. 015,0. 020) . At 18 months after treatment, SM fibrosis was significantly correlated with V60 of the upper SM ( P=0. 030);the fibrosis of neck skin was significantly correlated with the Dmean and V60 of the upper SM ( P=0. 029,0. 005) . Conclusions In order to prevent the incidence of the fibrosis of neck skin and SM, the dose homogeneity should be as high as possible, while the number of hot spots should be as small as possible.%目的：探讨放疗剂量与鼻咽癌患者胸锁乳突肌体积及晚反应关系。方法对2010—2014年间收治的38例鼻咽癌患者的胸锁乳突肌以环状软骨下缘分为上下颈部，根据CTV2处方剂量0、54、60 Gy分为1、2、3组。放疗剂量学参数包括整条肌肉和上下颈部的Dmean、V66、V60。在TPS的CT图像中分别勾画疗前和疗后6、12、18个月胸锁乳突肌轮廓并计算体积，在C3—C4、C4—C5、C5—C6、C6—C7椎间盘水平分别测量并记录胸锁乳突肌前后径及左右径。颈部皮肤、胸锁乳突肌晚反应采用CTCAE4.0标准记录。两两比较采用配对t检验或非参数Kruskal⁃Wallis法；单因素方差分析进行组间样本率比较；采用Spearman法行相关分析。结果疗后6、12、18个月SM体积变化之间差异有统计学意义（ P＝0.000）。疗后12、18个月胸锁乳突肌体积较疗前明显减小（ P＝0.000、0.000），且体积萎缩百分比与≥V66有明显相关性（ P＝0.015、0.020）。疗后18个月胸锁乳突肌纤维化与上颈部V60呈明显相关性（ P＝0.030）；颈部皮肤纤维化与上颈部Dmean、V60呈明显相关性（ P＝0.029、0.005）。结论放疗计划优化中应尽量提高剂量均匀度，以避免颈部皮肤及胸锁乳突肌纤维化发生。
展开▼
