鼻咽癌常规放疗中面颈联合野和下颈野衔接的探讨

The junction of the facio-upper neck field and the tangential low neck-supraclavicular field in conventional radiotherapy for nasopharyngeal carcinoma

目的:比较鼻咽癌常规放射治疗中面颈联合野和下颈切线野不同衔接方法及间距的衔接平面的剂量分布。方法:利用CMS计划系统来计算面颈联合野和下颈切线野在机架角0度方向上(即颈前部)共线衔接、间隔5mm衔接、重叠1mm和2mm衔接以及机架角在90度或270度方向上(即颈侧方向上)共线衔接平面的剂量分布。结果:两者在0度方向上共线衔接、间隔5mm、重叠1mm和2mm衔接以及在90度或270度方向上共线衔接时,衔接平面最高剂量分别是参考剂量的103%、54%、114%、124%、73%,而在0度方向上共线衔接、重叠1mm和2mm衔接平面的95%剂量曲线分别位于皮下2.5cm、0.8cm、0.4cm。结论:鼻咽癌常规放射治疗中面颈联合野和下颈切线野全束照射时推荐在0度方向上1mm的重叠衔接。

Objective：To compare the dose distribution at the match-plane of varies the junction methods and fields gap of the facio-upper neck field and the tangential low neck-supraclavicular field in conventional radiotherapy for nasopharyngeal carcinoma （NPC）. Methods：It was observated that the dose distribution at the match-plane of mono-line junction in the 0 degree direction, 5mm intervals, 1 mm and 2mm overlap, mono-line junction in the 90 degree direction of the facio-upper neck field and the tangential low necksupraelavicular field by three dimensions treatment planning system. Results：Maximun dose at the match-plane of mono-line junction in the 0 degree direction, 5mm intervals, 1 mm and 2mm overlap, mono-line junction in the 90 or 270 degree direction of the two fields were 103% ,54%, 114%, 124% ,73% of the weight dose,respectively; 95% isodose line at the match-plane of mono-line junction in the 0 degree direction, 1 nun and 2mm overlap of the two fields lied 2. 5cm, 0. 8cm,0. 4cm under the surface of skin, respectively. Conclusion： One millimeter overlap junction in the 0 degree direction of the two fields is recommended in the practical work.