Wu Vincent W C, Yang Zhi-Ning, Zhang Wu-Zhe, Wu Li-li, Lin Zhi-xiong
Department of Health Technology and Informatics, Hong Kong Polytechnic University, Kowloon, Hong Kong, China.
Med Dosim. 2012 Summer;37(2):122-6. doi: 10.1016/j.meddos.2011.02.003. Epub 2011 May 4.
This study compared the oral cavity dose between the routine 7-beam intensity-modulated radiotherapy (IMRT) beam arrangement and 2 other 7-beam IMRT with the conventional radiotherapy beam arrangements in the treatment of nasopharyngeal carcinoma (NPC). Ten NPC patients treated by the 7-beam routine IMRT technique (IMRT-7R) between April 2009 and June 2009 were recruited. Using the same computed tomography data, target information, and dose constraints for all the contoured structures, 2 IMRT plans with alternative beam arrangements (IMRT-7M and IMRT-7P) by avoiding the anterior facial beam and 1 conventional radiotherapy plan (CONRT) were computed using the Pinnacle treatment planning system. Dose-volume histograms were generated for the planning target volumes (PTVs) and oral cavity from which the dose parameters and the conformity index of the PTV were recorded for dosimetric comparisons among the plans with different beam arrangements. The dose distributions to the PTVs were similar among the 3 IMRT beam arrangements, whereas the differences were significant between IMRT-7R and CONRT plans. For the oral cavity dose, the 3 IMRT beam arrangements did not show significant difference. Compared with IMRT-7R, CONRT plan showed a significantly lower mean dose, V30 and V-40, whereas the V-60 was significantly higher. The 2 suggested alternative beam arrangements did not significantly reduce the oral cavity dose. The impact of varying the beam angles in IMRT of NPC did not give noticeable effect on the target and oral cavity. Compared with IMRT, the 2-D conventional radiotherapy irradiated a greater high-dose volume in the oral cavity.
本研究比较了常规七野调强放疗（IMRT）射野布置与另外两种七野IMRT射野布置在鼻咽癌（NPC）治疗中与传统放疗射野布置的口腔剂量。招募了2009年4月至2009年6月间接受七野常规IMRT技术（IMRT - 7R）治疗的10例NPC患者。利用相同的计算机断层扫描数据、靶区信息以及所有勾画结构的剂量限制，使用Pinnacle治疗计划系统计算了2种避免前野的替代射野布置的IMRT计划（IMRT - 7M和IMRT - 7P）以及1种传统放疗计划（CONRT）。为计划靶区（PTV）和口腔生成剂量体积直方图，从中记录剂量参数和PTV的适形指数，用于不同射野布置计划之间的剂量学比较。三种IMRT射野布置对PTV的剂量分布相似，而IMRT - 7R与CONRT计划之间差异显著。对于口腔剂量，三种IMRT射野布置未显示出显著差异。与IMRT - 7R相比，CONRT计划的平均剂量、V30和V - 40显著更低，而V - 60显著更高。两种建议的替代射野布置并未显著降低口腔剂量。NPC的IMRT中改变射野角度对靶区和口腔没有明显影响。与IMRT相比，二维传统放疗在口腔内照射的高剂量体积更大。
