螺旋断层放疗机束流输出稳定性测量及分析  

Measurement and Analysis of Beam Output Fluctuations for the Helical Tomotherapy System

作　　者：徐寿平[1] 戴相昆[1] 解传滨[1] 杨艳[1] 王连元[1] 巩汉顺[1] 葛瑞刚[1] 

机构地区：[1]解放军总医院放疗科,北京100853

出　　处：《中国医学物理学杂志》2009年第1期945-948,共4页Chinese Journal of Medical Physics

摘　　要：目的:Hi-Art 2.2.4螺旋断层放疗系统作为国内一种新的调强放射治疗设备,笔者通过20周实验测量,分析其剂量、能量输出变化情况,实现对螺旋断层放疗系统束流稳定性的检测,从而寻求建立起其有效的测量束流输出的质量保证体系。方法:按照每天在固定机架/固定床和旋转机架/固定床条件下测量该系统剂量输出,通过初始6周测量机器内循环水温对输出剂量的影响,20周时间内来实现考察该系统稳定性情况。在SSD=85cm、射野大小5cm×40cm条件下,采用矩形等效固体水1.5cm深度来实现固定机架静态剂量输出的测量;而射野大小5cm×40cm条件下利用圆柱形均匀等效水模体来测量旋转机架照射束流动态的稳定性。通过实施测量1.5cm、10cm及20cm不同深度处的剂量比值来对束流射线质变化予以评估。结果:在最初20周时间内Hi-Art系统束流输出剂量校准稳定性维持在±2%以内,而能量射线质保持在±1.5%以内。水温小于38℃条件下系统输出剂量存在一定的不确定性。结论:经过近5个月的测量分析,笔者建立起了Hi-Art螺旋断层放疗机束流输出稳定性测量体系。该系统为我院患者的调强放射治疗提供了一套稳定的平台,具有稳定动态/静态输出剂量和较小的能量变化漂移。Objective： The first clinical Hi-Art 2.2.4 helical tomotherapy system is new modality for delivering intensity modular ed radiation therapy. Here the output and energy fluctuations of the system have been reviewed for 20 weeks. To establish a kind of quality assurance system for the beam output measurement of Helical Tomotherapy. Methods： Fixed-gantry/fixed-couch and rotational-gantry/fixed-couch measurements were made on a daily basis over a period of 20 weeks to investigate system stability. The influence was analyzed by measuring the output with the water temperature in the initial 6 weeks. Static gantry measurements were taken at 1.5 cm depth in a rectangular stack of Virtual Water at an SSD distance of 85cm and a field size of 5 cm×40cm. Rotational gantry measurements were taken in a cylindrical symmetric Virtual Water phantom for a field size of 5 cm×40 cm. The energy was gotten using the dose ratio of the 1.5 cm, 10 cm and 20 cm measurement depth. Results： The Hi-Art system has maintained its calibration to within ±2% and energy to within ±1.5% over the initial 20 weeks period. The output of the system would be influenced when the inner water temperature was under 38℃. Conclusions： The output measurement system of our Hi-Art helical tomotherapy machine has been constituted over the initial 5 months period. The helical tomotherapy system has provided a stable platform for intensity modulated radiation therapy treatment of these patients with minimal output and energy fluctuations in our hospital.

关 键 词：螺旋断层治疗 剂量校准 输出测量 能量射线质 

分 类 号：K826.16[历史地理—历史学]