鼻咽癌调强放疗Ib区剂量分析

The Dose Analysis of Level Ib In Intensity Modulated Radiotherapy for Nasopharyngeal Carcinoma

目的:通过分析50例鼻咽癌调强放疗的TPS资料中Ib区、颌下腺的剂量分布特点,为个体化制定鼻咽癌调强放疗计划提供依据。方法:50例于2011年1月至2011年6月接受调强放射治疗(IMRT)的初治鼻咽癌患者被纳入研究。收集所有患者IMRT计划的TPS数据,分析其Ib区、颌下腺计划外受照射体积剂量特点。结果:50例TPS数据中双侧Ib区平均体积为9.03 mm3±2.22 mm3,平均剂量达52.42 Gy±4.30 Gy,V30、V35、V40、V45、V50、V55、V60的百分比分别为99.4%、83.1%,94%、83.1%、64.3%、58.1%、35.5%、21.6%。双侧颌下腺平均体积为7.03 mm3±1.05 mm3,平均剂量为58.51 Gy±5.35 Gy,接受30 Gy、40 Gy、50 Gy、60 Gy的体积分别为100%、99.1%、89.7%、71.2%。结论:在鼻咽癌调强放射治疗中,即使Ib区不予预防照射,Ib区和颌下腺均已接受较高的计划外照射。颌下腺的计划外剂量已经超出其功能保全剂量。

Objective： By analyzing the characteristics of dose distribution of the level-Ib and submandibular gland in 50 cases TPS data of nasopharyngeal carcinoma treated with intensity modulated radiotherapy to provide a certain reference for the choice of treatment strategy. Methods： Between January 2011 and June 2011,TPS （Treatment Planning System） data of 50 consecutive IMRT treated NPC patients was collected. The unplanned irradiation dose of level- I b and submandibular gland were analyzed. Results： In the TPS date of 50 cases,the average volume of bilateral level- I b was 9.03 mm^3±2.22 mm^3, the average dose was 52.42 Gy±4.30 Gy, and the rates of V30,V35,V40,V45,Vs0,V55,V60 were 99.4% ,83.1% ,94% ,83.1% ,64.3%, 58.1%, 35.5%, 21.6% respectively. The average volume of bilateral submandibular gland was 7.03 mm3± 1.05 mm^3, the average dose was 58.51 Gy±5.35 Gy,and the volume ratios of 30 Gy,40 Gy,50 Gy,60 Gy were 100%,99.1%,89.7%,71.2% respectively. Conclusions： Level-Ib and submandibular gland seems to receive a high dose of external irradiation in the nasopharyngeal carcinoma intensity modulated radiation therapy, even if the level-Ib has not been given a preventive irradiation. The unplanned dose of submandibular glands has been beyond its functional preservation dose.