【摘要】 目的 研究楔形因子与照射野大小和测量深度的相关性,为临床准确使用该因子提供依据。方法 通过对SIEMENS MD7745直线加速器,6MV-X线,60度楔形滤片下不同大小的照射野且不同深度分别测量加和不加楔形滤片时的剂量率,计算楔形因子。然后以实际常用的两种标准条件下的楔形因子Fw(10 cm×10 cm、d=10 cm)和Fw(10 cm×10 cm、dmax=1.5 cm)为标准数据计算误差分布。结果 得到了各种照射情况下的楔形因子和误差分布及修正方法。结论 照射野大小和测量深度对楔形因子Fw均有影响:其中照射野的影响不大,可忽略;但测量深度的影响却很大,不能忽略。为了达到WHO放射治疗质量保证和质量控制有关楔形因子的精度必须好于2%的规定,在临床实际工作中必须实测并修正测量深度对楔形因子Fw的影响。更多还原

【Abstract】 Objective To study the relation between the field size and depth of Fw (wedge factor) and its effect on the clinical usage. Methods First, we measured the dose rate with and without containing 60°wedge filter for different field and depth on Siemens MD7745 linear accelerator by Capintec292, then we got the Fw for different fields and depths,after then,we calculated the deviations under the two conditions that we assume the Fw (10 cm × 10 cm, d= 10 cm) or the Fw (10 cm × 10 cm, dmax =1.5 cm) as the standard data. Results We got the Fw for field from 3 cm × 3 cm to 15 cm × 20 cm and the depth from 1.5 cm to 15 cm,and we got the deviations for the different conditions. Conclusion We believe the field size and may affect on the Fw,but the influence from field is small and can be neglect; yut the influence from depth cannot be neglect. It is suggested that the measurement and usage of Fw according to fields and depths in use for the accurate dosimetry in order to attend the rules from WHO that the accurate for Fw must be better than 2 % .更多还原