摘要
目的:探讨不同多叶准直器(multileaf collimator,MLC)叶片宽度对调强放疗(intensity modulated radiotherapy,IMRT)治疗计划的影响。方法: 用ADAC Pinnacle 3型计划系统,对实施IMRT 的11 例鼻咽癌患者,分别用叶片等中心宽度5 mm 和10mm的MLC制定放疗计划,依照剂量体积直方图(dose volume histogram, DVH)对靶区剂量进行综合分析评价,并比较适形指数(radiation conformal index, CI)和剂量均匀指数(homogeneity index,HI)。结果:两种治疗计划的靶区剂量配对t检验显示,靶区和腮腺之间差异有统计学意义,P<0 .05(P值分别为0 .036、0. 002 和0. 001);脑干及脊髓之间差异无统计学意义,P>0 .05(P值分别为0 327和0 545)。5 mm MLC 计划的靶区平均剂量略高于10 mm MLC计划,而两侧腮腺、脑干、脊髓的剂量降低。5 mm MLC计划的CI值明显高于10 mm计划的CI值,t= 9 .779,P= 0 .000。两种计划的HI 值差异无统计学意义,t= 1 257,P= 0 .237。结论:5 mm MLC与10 mm MLC比较,前者适形度好,靶区剂量更均匀,更适合于形状不规则而且邻近危险器官的病灶IMRT。
OBJECTIVE: To study the efficacy of using differential multileaf collimators in the treatment of nasopharyngeal carcinoma (NPC) by intensity-modulated radiotherapy techniques( IMRT). METHODS: Eleven patients with NPC were administered and analyzed. The penumbra characteristics, dose of target, radiation conformal indexes (CI) and homogeneity indexes (HI) of 10 mm and 5 mm MLC were measured and compared with dose volume histogram(DVH) generated by a commercial three-dimensional planning computer system. RESULTS: Comparison of dose distributions of target volume and parotid indicateed that there was a significant statistical difference, P <0.05 between the two treatment planning ( P =0.036,0.002 and 0.001). The mean dose of target region in 5 mm MLC treatment planning was higher than that in 10 mm MLC, while the mean dose of two parotids, brain stem and spinal cord in 5 mm MLC treatment planning were lower than in 10 mm MLC, the radiation conformal index in 5 mm MLC treatment planning was higher than that in 10 mm MLC, t =9.779, P =0.000. The homogeneity indexes had no difference between the two treatment plannings, t =1.257, P =0.237 . CONCLUSIONS: By comparing CIs and HIs obtained with 10 mm and 5 mm MLC, the 5 mm MLC is a stable, high precision field-shaping device, more suitable for IMRT applications than 10 mm MLC. It is especially useful for optimizing the orientations in the case of target volumes of complex shape or when volumes at risk are in the vicinity of the target.
出处
《肿瘤防治杂志》
2005年第8期611-613,共3页
China Journal of Cancer Prevention and Treatment
关键词
多叶准直器
调强放疗
适形指数
剂量均匀指数
multileaf collimator
intensity-modulated radiotherapy
radiation conformal index
homogeneity index
