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[目的]分析总结鼻咽癌(NPC)斜坡侵犯的MRI表现与IMRT靶区勾画的关系。[方法]100例经确诊初治无处远转移的鼻咽癌病例,所有病例放疗前均接受MRI检查并分析斜坡信号异常及浸润范围。选取5例斜坡侵犯者进行IMRT靶区勾画及计划设计,其GTVnx后缘分别按斜坡前缘、斜坡1/2、斜坡后缘三个解剖位置进行勾画,分析靶区勾画位置与等剂量曲线包容的相关性。[结果]100例中有62例斜坡异常。三个不同解剖位置GTV后缘距脑干的最短平均距离分别为16.0mm、11.5mm、7.0mm。GTVnx被100%的处方剂量(7200cGy)包绕的体积百分比分别为95%、91%、85%。[结论]NPC斜坡侵犯MRI表现较为复杂,勾画靶区时应充分考虑不同MRI表现,根据信号异常的程度和范围给予不同处方剂量。
[Objective] To summarize the relationship between MRI manifestations of nasopharyngeal carcinoma (NPC) slopes invasion and IMRT target area sketches. [Method] One hundred cases of nasopharyngeal carcinoma which had been diagnosed as having no metastasis at first treatment were studied. All the patients underwent radiological examination before radiotherapy and analyzed the slope signal anomaly and infiltration range. The target area of IMRT was selected and the design of the IMRT target was selected. The trailing edge of GTVnx was delineated according to the three anatomical positions of the leading edge of the slope, the slope of 1/2 and the posterior edge of the slope, respectively. Relevance. [Results] There were 62 cases of slope anomaly in 100 cases. The shortest distances between the trailing edge of GTV and brainstem in three different anatomical locations were 16.0mm, 11.5mm and 7.0mm respectively. The volume percentages of GTVnx surrounded by a 100% prescription dose (7200 cGy) were 95%, 91% and 85%, respectively. [Conclusions] The performance of NPC slope invasion MRI is more complicated. The target area should be fully considered with different MRI manifestations, and different prescription doses should be given according to the extent and range of signal anomalies.