多丝电离室(DAVID)系统对加速器射束的影响  

The Multi-wire Ionization Chamber(DAVID)'s Influence on the Beams of Accelerator

作　　者：徐慧军[1] 李玉[1] 张素静[1] 韩萍[1] 张军华[1] 

机构地区：[1]解放军第302医院肿瘤放射治疗中心,北京100039

出　　处：《中国医学物理学杂志》2013年第1期3841-3844,共4页Chinese Journal of Medical Physics

基　　金：军事医学计量专项课题(2011-JL2-050)

摘　　要：目的:通过测量未安装和已安装DAVID系统两种情况下加速器射束的参数,分析DAVID系统对射束的影响。方法:西门子ARTISTE直线加速器,配备160叶多叶光栅,选择6 MV的X线。多丝电离室(DAVID),型号为T34084。利用三维水箱、半导体探测器等仪器测量未安装和已安装DAVID系统两种条件下PDD、profile、TPR20/10和水下5 cm吸收剂量,分析DAVID系统对加速器射线束PDD、平坦度、对称性、射线质的影响,并计算出DAVID系统的衰减系数。结果:无和有DAVID两种条件下,5 cm×5 cm、10 cm×10 cm和20 cm×20 cm三个射野R100偏差在0.6 mm^1.3 mm,R80偏差在0.13 mm^0.66 mm,R50偏差在0.38 mm^1.12 mm;40 cm×40 cm的射野R100、R80和R50的偏差分别为3.12 mm、3.31mm和2.04 mm;QI的偏差分别为0.0020、0.0045、0.0101、0.0061;x和y方向平坦度偏差在0.10%~0.58%,对称性偏差在0.04%~0.26%;TPR20/10的偏差0.002。射线穿过DAVID,使剂量衰减了7.67%。结论:DAVID系统的复杂结构和材料对6MV的X射线束的PDD、对称性、平坦度和TPR20/10影响甚微,最主要的是射线经过DAVID系统造成了剂量的衰减。Abjective： Through measuring the parameters of the accelerator beams under two conditions of uninstalled and in- stalled DAVID system,to analyze DAVID system＇s influence on the beams. Methods： We chosed the Siemens ARTISTE Linear Accelerator which was allocated with a 160 MLC multi-leaf collimator, and the 6 MV X-ray was used. The model number of the multi-wire ionization chamber was T34084. Utilizing the equipments like 3D water tank and semiconductor de- tector to measure PDD, profile, TPR^10 and the absorbed dose underwater 5 cm under the conditions of uninstalled and in- stalled DAVID system, we analyzed DAVID system＇ s influence on the PDD, flatness, symmetry and actinogen of accelerator beams, and calculated the attenuation coefficient of DAVID system. Results： Under the two conditions of uninstalled and in- stalled DAVID system, the R^00 deviation of the three fields （5 cmx5 cm~ 10 cmxl0 cm and 20 cmx20 cm） lay between 0.6 mm -1.3 mm, Rs0 deviation of them lay between 0.13 ram-0.66 mm, and Rso deviation lay between 0.38 mm-l.12 mm. The Rl00, R^o, and Rs0 deviation of the fields of 40 cmx40 cm were 3.12 mm, 3.31 mm and 2.04 mm; The QI deviations were 0.0020, 0.0045, 0.0101, and 0.0061; The flatness deviation in the x and y direction was between 0.10%-0.58%; The symmetry devia- tion lay between 0.04%-0.26%; And the TPR20/10 deviation was 0.002. The beams went across DAVID system and attenuated 7.67% of the dose. Conclusions： The comprehensive structure and making materials of DAVID system have little effect on the PDD, symmetry, flatness, and TPR2~0 of the 6 MV X-ray beams, but the beams attenuate the dose when going across DAVID system.

关 键 词：多丝电离室 加速器 射束 影响 

分 类 号：R811.1[医药卫生—放射医学]