河南省医用加速器多叶光栅小野输出因子验证测量方法研究  

Methods of verification and measurement of MLC-defined small field output factors for eight medical accelerators in Henan province

作　　者：程晓军 胡传朋 贾陈志 罗素明[2] 吴昊[3] 

机构地区：[1]河南省职业病防治研究院,郑州450052 [2]中国疾病预防控制中心辐射防护与核安全医学所辐射防护与核应急中国疾病预防控制中心重点实验室 [3]北京肿瘤医院

出　　处：《中华放射医学与防护杂志》2015年第10期780-783,共4页Chinese Journal of Radiological Medicine and Protection

基　　金：IAEA基金资助项目（17821/CRP）

摘　　要：目的调查放射治疗计划系统（TPS）计算的多叶光栅（MLC）小野输出因子，研究用0．015cc电离室验证小野输出因子的测量方法。方法在河南省选择8台可开展调强放射治疗的医用加速器，调查TPS计算的小野输出因子并与国际原子能机构（IAEA）推荐的出版值进行比较。如果2cm×2cm照射野相对偏差超出IAEA要求的±3％，3cm×3cm、4cm×4cm、6cm×6cm照射野相对偏差超出IAEA要求的±2％，则用0．015cc电离室和Unidos剂量仪进行测量验证。结果8台医用加速器的TPS计算小野输出因子与出版值比较，5台相对偏差符合IAEA要求，占调查总台数的62．5％，3台相对偏差超过IAEA要求，占调查总台数的37．5％。用针尖电离室测量验证，3台测量结果均符合IAEA要求。结论河南省部分医用加速器TPS计算的MLC小野输出因子，需要现场实施小电离室测量修正，测量值作为制定放射治疗计划的依据。Objective To investigate muli-leaf collimator （MLC）-defined small field output factors calculated by the treatment planning system （TPS） , and to study the measuring method of small field output factors verified by 0. 015 cc PinPoint ionization chamber. Methods Eight medical accelerators for intensity-modulated radiation therapy （IMRT） were investigated in Henan province, and TPS-calculated output factors for various small fields （6 cm×6 cm,4 cm ×4 cm,3 cm ×3 cm and 2 cm ×2 cm ） were compared with published values recommended by IAEA. If the relative deviation was more than ± 3% for the2 cm×2 cm field size and ±2% for the fields of 6 cm×6 cm, 4 cm×4 cm and3 cm×3 cm, which was beyond the scope of IAEA allowed, the output factors will be measured and verified using 0. 015 cc PinPoint ionization chamber and Unidos electrometer. Results TPS-calculated small field output factors for eight medical accelerators were compared with published values. The relative deviation of small field output factors for five pieces of equipment, which accounted for 62.5% of the total, met the IAEA＇ s requirement, while the other three, which accounted for 37.5% of the total, did not. After measuring with PinPoint ionization chamber, the results from only three pieces of equipment met minimum IAEA＇s requirement. Conclusions MLC-defined small field output factors calculated by TPS for some medical accelerators in Henan need to be measured and corrected using micro-ionization chamber, and the measured values could be taken as the basis of radiation treatment planning.

关 键 词：调强放射治疗 小野输出因子 多叶光栅 治疗计划系统 

分 类 号：R730.55[医药卫生—肿瘤]