摘要
目的研究直线加速器高能电子束输出因子的影响因素,为临床准确使用该因子提供依据。方法以西门子MD7745和通用Saturne41直线加速器12 MeV和9 MeV高能电子束为辐射源,测量不同射野边长最大剂量点剂量率,计算输出因子,然后分析数据。结果西门子MD7745加速器使用电子束的射野输出因子应:①限光筒尽量接近实际射野边长,即边长小于10 cm的射野,使用10 cm×10 cm限光筒浇铸射野模型;射野边长10~15 cm,使用15 cm×15 cm限光筒浇铸射野模型;大于15 cm的射野边长使用20 cm×20 cm限光筒浇铸射野模型;②当射野边长大于电子束射程时,使用标准限光筒的输出因子进行剂量计算;而边长小于电子束射程时,必须按临床射野情况有针对性地实际测量输出因子的大小进行剂量学的计算。而对通用Saturne41型直线加速器,必须测量并制作输出因子射野两维表,并进行临床处方剂量的计算。结论实际工作中,对西门子MD7745型直线加速器这样的电子束射野成形模式,限光筒大小应尽量接近临床实际射野大小;而对通用Saturne41型直线加速器这样的电子束成形模式,必须测量输出因子射野两维表并应用于临床处方剂量的计算。
Objective To study the influencing factors of output factors of high-energy electrons for linear accelerators, so as to provide evidence for accurate clinical application. Methods We measured the dose rate for different fields at dmax depth for 12 MeV and 9 MeV high-energy electrons by SIEMENS MD7745 and GE Saturne41 medical linear accelerators, calculated the output factors, and analyzed the data. Results For SIEMENS MD7745 accelerators:① The electron cones should be similar to the actual field, 10 cm×10 cm electron cone model should be used when the actual field was less than 10 cm; 15 cm× 15 cm electron cone model should be used when the actual field was 10-15 cm; and 20 cm× 20 cm electron cone model should be used when the actual field was larger than 15 cm. ② When the length of actual field was larger than the field of the electrons, the dosage was calculated by the output factor of standard electron cone; when the length of the actual field was less than the field of the electrons, the dosage should he measured according to the actual measurement of the output factors. For GE Saturne41 accelerators, the two dimensional chart of output factor field should be measured and plotted and the clinical dosage should be calculated. Conclusion For SIEMENS MD7745 accelerator, the size of the electron cone should he similar to the actual electron field; for GE Saturne41 accelerator, the two dimensional chart should be plotted and the clinical dosage should be calculated.
出处
《上海医学》
CAS
CSCD
北大核心
2008年第6期434-437,共4页
Shanghai Medical Journal