医科达Synergy-S加速器多叶准直器剂量学研究  

Study on the dosimetrics of multi-leaf collimator of ELEKTA Synergy-S medical linear accelerator

作　　者：李军[1] 张西志[1] 张先稳[1] 桂龙刚 孙新臣 李金凯 LI Jun;ZHANG Xi-zhi;ZHANG Xian-wen

机构地区：[1]苏北人民医院放疗科,江苏扬州225001 [2]南京医科大学第一附属医院放疗中心,江苏南京210029

出　　处：《中国医学装备》2018年第4期39-42,共4页China Medical Equipment

摘　　要：目的:测量Synergy-S医用直线加速器新型多叶准直器(MLC)的漏射和透射剂量,分析漏射和透射剂量产生的原因。方法:应用PTW UNIDOS剂量仪和MP3三维水箱,分别在水中、空气中以及RW3固体水模中测量Synergy-S加速器内置的Beam Modulator型MLC叶片间和叶片端面的X射线漏射,以及漏射随射线能量和机架角度的变化。结果:能量对叶片间漏射稍有影响,对叶片端面透射剂量影响较小,重力和MLC的运动对叶片间透射影响较小,偏轴方向两测量点漏射率很低,且有随离轴距离越远漏射呈降低趋势。结论:随着调强放射治疗以及旋转弧形调强放射治疗技术的应用,由于使用子野或野中野调强放射治疗技术,单次照射的机器输出跳数很高,对MLC的透射要求越来越高。因其叶片间透射线的存在,在优化放射治疗计划时还应根据情况转动机头,利用铅门再次遮挡重要危及器官和正常组织,以降低辐照风险。Objective:To measure the leak dose and transmission dose of new type of multi-leaf collimator(MLC)of ELEKTA Synergy-S medical linear accelerator,and analyze the reasons for leak dose and transmission dose.Methods:PTW UNIDOS dosimeter and MP3 3D water tank were applied to measure leak of X-ray at inter-leaf and leaf-face of BeamModulator MLC of Synergy-S accelerator at in-water,in-air and RW3 solid phantom,respectively.Besides,the change of leak with the change of energy and rack angle also were measured.Results:Energy has a few influence for the leak of inter-leaf,while its influence was lesser for transmission dose of leaf-face.And the gravity and movement of MLC have a few influence on the transmission dose at inter-leaf.Besides,the leak rate of two detection points on the direction of off-axis was very low,and it has a trend that leak rate was decrease with the increasing of distance away from off-axis.Conclusion:With application of IMRT and VMAT,the requirement for MLC transmission also is more and more higher because machine unit of single time is very high in the using of IMRT technique on descent field or field in field.Because the existed transmission ray at inter-leaf,the machine head should be rotated according to actual situation when the radiotherapy plan is optimized,and lead door should be applied to shield important risk organ and normal tissue again so as to reduce the risk of radiation.

关 键 词：多叶准直器 漏射 透射剂量 放射治疗 医用直线加速器 

分 类 号：R814.2[医药卫生—影像医学与核医学]