二维电离室矩阵在近距离治疗的质量保证中的应用  

Application of a Tow-dimension Ion Chamber Arrary for Quality Assurance in Brachytherapy

作　　者：刘浩[1,2] 李公平[1] 孙燕 吐尼沙 吴恒[2] 马栋辉[2] 王巨武[2] 

机构地区：[1]兰州大学核科学与技术学院,甘肃兰州730000 [2]新疆医科大学附属肿瘤医院放疗中心,新疆乌鲁木齐830011

出　　处：《中国医学物理学杂志》2011年第4期2718-2721,共4页Chinese Journal of Medical Physics

摘　　要：目的:测量后装治疗机在执行治疗计划过程中放射源在各驻留点的实际驻留时间,并与计划的驻留时间比较;观察放射源到达驻留位置的重复性。方法:利用IBA MATRIXX测量科霖众制造的后装治疗机。把一个透明的食管后装适源器固定在MATRIXX表面,用后装计划系统设计一个后装计划,治疗长度为15 cm,驻留点间距为0.5 cm,共计31个驻留点,总治疗时间为105 s,各驻留点时间权重相等。执行该后装治疗计划10次,记录下MATRIXX的测量数据。在测量过程中,MATRIXX选择MOVIE模式,每次测量采样时间为0.1 s。结果:放射源在各驻留点的驻留时间均为3.4秒,总治疗时间为105.4 s,与计划时间相差0.4%;31个驻留点因放射源到位置偏差引起各相应的主测量电离室计数值的相对标准偏差均小于10%。结论:用二维矩阵电离室验证后装治疗过程中放射源的驻留时间和到达驻留位的重复性是可行的。选择较小的测量采样时间,可提高测量驻留时间的精度。Objective: To measure the dwell time of the radiological source during performing the brachytherapy plan,to compare the measured data with the designed data,and to investigate the reproducibility of reaching the dwell position of radiological source.Methods:We designed a brachytherapy plan: the treatment length was 15 cm,31 dwell positions were arranged at 0.5 cm intervals,the time weight of each position was equal,the total treatment time was 105 seconds.The transparent X-ray catheter for esophagus was used in the plan.We performed the plan ten times using the Kelinzhong afterloader system and measured the radiological source using the IBA MATRIXX in movie model with 0.1 second sample time.Results: The measured dwell time of each dwell position is 3.4 seconds,the total treatment time is 105.4 seconds and more 0.4% than the designed time.The relative deviation of main ion chamber data is less than 10%.Conclusions: It is feasible to verify the dwell time and the dwell position reproducibility of the radiological source in performing the treatment plan.The smaller the sample time is,the higher the precision of the dwell time is.

关 键 词：二维电离室矩阵 近距离治疗 驻留时间 

分 类 号：R312[医药卫生—基础医学]