多叶准直器射野处方剂量的快速计算  

Rapid calculation of the monitor units for multileaf collimator shaped irregular fields

作　　者：戴建荣[1] 胡逸民[1] 杨勇[1] 

机构地区：[1]中国医学科学院中国协和医科大学肿瘤医院放射治疗科,北京100021

出　　处：《中华放射肿瘤学杂志》2000年第2期131-134,共4页Chinese Journal of Radiation Oncology

摘　　要：建立一种计算多叶准直器 (MLC)不规则射野处方剂量的快速方法。方法　考虑到MLC射野的边缘是台阶状、叶片位置坐标可以由治疗计划系统或与MLC配套的叶片位置产生器打印输出这两个特点 ,首先由叶片位置坐标计算出射野周长和面积 ,然后由面积周长比法计算出不规则野的等效方野边长 ,最后按照处理常规方野的方法计算处方剂量。结果　作为例子 ,计算了采用SSD技术的全脑全脊髓照射野和采用SAD技术的鼻咽癌面颈联合野的处方剂量。结论　这种方法适合于靶区参考点位于射野中心区域未被遮挡的情况。与Clarkson积分等其它方法相比 ,它具有快速简单的特点。Objective To develop a rapid algorithm in the calculaton of machine monitor units for irregular fields shaped by multileaf collimator (MLC). Methods On considering that the fields' edges are stepwise and the leaves' coordinates can be printed out by a treatment planning system or outlined by a MLC shaper, their area and perimeter can be directly calculated from leaves' coordinates. Then the equivalent field size can be calculated with methods based on the area/perimeter ratio. Finally, the monitor units can be determined from a well-known formula. Results As examples, the total brain-spinal cord field, which was delivered with nominal SSD technique, and head-neck field, which was delivered with SAD technique, were calculated. Conclusions This algorithm is suitable to the situation when the reference point of target dose is located at the central part of a field and has not been blocked. It is quicker and simpler as compared with the other methods such as Clarkson integration.

关 键 词：多叶准直器 不规则射野 处方剂量 鼻咽肿瘤 

分 类 号：R14[医药卫生—公共卫生与预防医学]