摘要
目的:探讨Varian直线加速器全碳纤维治疗床对放疗剂量的影响。方法:将固体水模置于主床板、衔接处、延长板的中心处,改变机臂角度,从不同角度让不同能量的高能X射线穿透治疗床,通过对比测量计算出穿透因子。利用放射治疗计划系统设计加床和不加床的计划,测量绝对剂量的误差。结果:6、15 MV X线,主床板和延长板的穿透因子在机架角105～120°区间较低,主床板在115°时最小,穿透因子分别为0.954 4、0.968 5;延长板在110°时最小,穿透因子分别为0.914 7、0.924 7;衔接处的穿透因子远小于主床板和延长板,120°时最小,分别为0.484 8、0.586 0。利用TPS设计放射治疗计划加虚拟床后,实测剂量更接近计划中的计算值。结论:随着床板厚度的增加,穿透因子减小;主床板和延长板对剂量的衰减接近,衔接处衰减最大,摆位时应避免射野穿过;能量越高,穿透因子越大;在设计放射治疗计划时,加虚拟床是必要的。
Objective To investigate the effect of whole carbon fiber couch of Varian Linear Accelerator on radiotherapy dose. Methods The solid water phantom was fixed at the center of main couch, engage part and extended plank. The high energy X-ray penetrated different couch plank from different angles, and the penetration factor of X-ray decline was calculated by measurement and comparison. Radiotherapy plans with couch and non-couch were designed by treatment planning system. Results The penetration factor of 6 MV and 15MV X-ray declined within the angle from 105 to 120 when main couch and extended plank were used. Min penetration factors of main couch at angle 115, were 0.9544 and 0.9685 respectively. Min penetration factors of extended plank at angle 110, were 0.9147 and 0.9247 respectively. Min penetration factors of engage part at angle 120, were 0.2817 and 0.5860 respectively, smaller than main couch and extended plank. The measured dose resemble to the computed value of the plan with couch which were designed by treatment planning system. Conclusion With the couch plank thickness increased penetration factor decreases. The main couch and extended plank for dose attenuation close, engage part has maximum attenuation. The higher energy is accompanied with larger penetration factor. Virtual couch must be used when designing radiotherapy treatment plan.
出处
《医疗卫生装备》
CAS
2012年第7期108-109,122,共3页
Chinese Medical Equipment Journal
关键词
直线加速器
治疗床
穿透因子
放射治疗
linear accelerator
treatment couch
penetration factor
radiotherapy
