PTW1000SRS与729矩阵在非均整模式下剂量验证对比

Comparison of dose verification of flattening filter-free model by using PTW 1000SRS and 729 arrays

目的:比较PTW OCTAVIUS 1000SRS和729在非均整模式下立体定向放射治疗(SBRT)和立体定向放射外科治疗(SRS)中的剂量验证结果。方法:选取20例非均整模式的SBRT和SRS计划,分别采用PTW公司1000SRS和729二维电离室矩阵进行剂量验证,对比分析其通过率、评估点数及未通过区域。结果:采用Gamma 2D(按3 mm和3%的误差标准),local dose方法进行分析,1000SRS矩阵通过率为(97.6±1.8)%,评估点数平均为1191,未通过区域集中在射野边缘,而729矩阵通过率为(94.8±2.7)%,平均评估点数为155,未通过区域集中在低剂量区。结论:对于高剂量率、高剂量梯度的非均整模式下的SBRT和SRS计划验证,1000SRS液体电离室矩阵具有较大的优势。

Objective To compare the dose verification of stereotactic body radiotherapy （SBRT） and stereotactic radio-surgery （SRS） with flattening-filter-free （FFF） model by using PTW OCTAVIUS 1000SRS and 729 ionization chamber arrays. Methods Twenty SBRT and SRS plans with FFF model were selected and measured by PTW OCTAVIUS 1000SRS and 729 two-dimensional ionization chamber array respectively. The passing rate, evaluated points and failed area were compared and analyzed. Results Based on Gamma 2D criteria of 3 mm/3%, local dose method was applied to analyze the result. The pass rate and average evaluated points of 1000SRS array were respectively （97.6± 1.8）%, 1191, while those of 729 array were respectively （94.8±2.7）%, 155. The failed area of 1000SRS array was mainly at the field edge, and that of 729 array was mainly in the low dose region. Conclusion For the dose verification of SBRT and SRS treatment plans involving the FFF model of high dose rate and high dose gradient, 1000SRS liquid ionization chamber array has great advantages.