鼻咽癌放疗过程腮腺体积与位置变化的观察

Research for the volume and center-location variation of parotid glands in the course of radiotherapy to nasopharyngeal carcinoma

目的探讨鼻咽癌根治性放疗过程中腮腺随照射剂量的增加而产生的体积以及位置变化。方法选取中山大学肿瘤防治中心2012-01-27-2013-07-05收治13例鼻咽癌患者为研究对象,在首次计划设计和患者接受20、40和60Gy剂量照射以及完成治疗后3个月行CT扫描,在断层图像上逐层进行腮腺轮廓勾画,计算腮腺体积和中心位置的变化。结果 13例患者在接受20、40和60Gy的剂量照射时,腮腺体积与原来比较分别减少13.2%、29.6%和33.6%;完成治疗3个月后,腮腺与治疗前比较体积缩小24.0%。两侧腮腺中心位置在放疗过程中,左侧x轴移动-1.184±2.808,y轴为-0.650±3.555,z轴为-2.759±2.294;右侧x轴为0.560±2.346,y轴为-0.256±1.601,z轴为-1.582±2.865。结论随着照射剂量增加,两侧腮腺体积明显缩小,放疗结束后3个月明显恢复。两侧腮腺中心位置也随着放疗剂量增加向内侧和后侧移动。设计二次放疗计划时可以此为参考依据。

OBJECTIVE To analyze the volume and center-location variation with the increasing of the dose in the radiotherapy of nasopharyngeal carcinoma. METHODS Thirteen NPC patients treated with IMRT in Sun Yat-sen University Caner Center were selected randomly from 27th Jan 2012 to 5th July 2013. The CT was scanned including the first scan for the design of treatment planning and when 20,40,60 Gy were given and 3 months after the radiotherapy. Parotid glands were contoured by the same doctors on all the images,and then the change of the volume and center-location was statistically analyzed. RESULTS The average volumes of parotid glands were decreased 13. 2%, 29. 600 and 33. 6% when 20,40,60 Gy were given and 3 months after the radiotherapy compared with the first scan for the design of treat- ment planning. The change of center was as follows： Left （x：- 1. 184±2. 808; y：--0. 650±3. 555; z：-2. 759± 2.294）;Right （x：0.560±2.346; y：-0.256±1.601; z：-1.582±2.865）. CONCLUSIONS With the increasing of dose, the volume of parotid glands decreases obviously. It will be renewed 3 months after the process of radiotherapy. The center of parotid glands shifts towards inside and back regularly with the increasing of dose. This trend can be used to design the secondary radiation planning.