动态楔形因子在肿瘤放射治疗临床剂量计算中的应用

目的：动态楔形技术即在加速器治疗时用计算机控制铅门的运动以使X线在所设定的照射野和深度处得到治疗所需要的楔形等剂量线分布,以代替传统的物理楔形板。在1978年,P.K.Kijewski等人1]提出动态楔形技术（DW）之后,上个世纪90年代,John.P.Gibbons2]提出了将动态楔形技术应用于临床,并对Varian加速器作了大量的研究。但对于Siemens医用直线加速器报道尚少。方法：本文以Siemens Primus医用直线加速器为研究对象,在水箱中放入0.6 cc电离室并与NE2620型剂量仪相连,分别对6 MV和15 MV光子线在dmax深度处进行测量。通过实验,找出适合Siemens Primus医用直线加速器的动态楔形临床剂量计算公式。结果：在实验过程中,我们发现,按照经验公式所拟合出来的公式与通过与Siemens Primus医用直线加速器的动态楔形因子的计算公式及公式中出现的参量3]的理论值比较,即文中的公式理论值与实验值的比较,在用于临床时,我们发现,实验拟合出来的公式满足临床要求,误差结果在1%～2%内。结论：对于Siemens Primus加速器,在应用动态楔形技术时,对于对称野在临床剂量计算过程中,可以不考虑EDWF值,即与常规剂量计算一样。

Dynamic Wedge Factor in Tumor Radiotherapy Clinical Application of Dose Calculation

Objective: Dynamic wedge treatment technology,that is used by computer-controlled accelerators jaws move to make the X-ray radiation at the required filed and depth produce the wedge-shaped isodose distribution to replace the traditional physical wedge.In 1978,after P.K.Kijewski etc1 had developed dynamic wedge technology(DW).Last century 90 ’s,John.P.Gibbons2] made a dynamic wedge technology applied in clinical,and the technology began to be applictted in Varian accelerator.But for Siemens accelerator report is less.Methods: On that issue,the paper makes the test on the object of Siemens Primus linear accelerator.The 0.6cc ionization chamber placed in the water and connected with the NE2620-type dosimeters,by measured at the maximum depth for 6 MV and 15 MV.Through the experiment,we find suitable Siemens Primus medical linear accelerator for the clinical dose calculated dynamic wedge.And according to the results,the best clinical dose calculation formulas is found for Siemens Primus accelerators.Results: Through the test,we found that,by comparison,in for clinical,according to Siemens linear accelerator dynamic wedge shape factor calculation formula and the formula appears in the parameter3] when used in clinical,experimental fitting out of the equation satisfy the clinical requirements,the error in the range of 1%~2%.Conclusions: For the Siemens Primus accelerator,dynamic wedge in the application of dose calculation in tumor radiotherapy,the clinical dose for symmetrical field calculation,we can not consider EDWF value,that is the same as with conventional dose calculation.