基于菊花链射野输出因子测量方法

摘要

Objective improve the accuracy of the measurement results by using the field output factor measurement method based on daisy-chaining.Methods The Varian Edge Accelerator 6 MV X-ray data were measured using the IBA CC13 ionization chamber, IBA CC01 ionization chamber, IBA Razor semiconductor detector , IBA EFD semiconductor detector and Gafchromic EBT 3 film , respectively. Results Compared with the daisy-chaining measurement method,the results obtained by the conventional measurement method using CC13 were smaller. The deviation value was 16. 71% in the 1 cm × 1 cm field. The measurement results in a larger field via CC01 were bigger with a deviation of 8. 39% in the 40 cm × 40 cm filed. The measurement results via Razor in a larger field were larger with a deviation of 9. 40% in the 40 cm × 40 cm field. The measurement results were similar between EFD and Razor with a deviation of 9. 14% in the 40 cm × 40 cm field. The results of the film measurement were equivalent to those obtained from the daisy-chaining method in a field of＞ 1 cm × 1 cm with a deviation within 1. 60%,whereas the deviation was increased to 3. 13% in the 1 cm× 1 cm field. The results were consistent with daisy-chaining measurement if the 3 cm × 3 cm or 4 cm × 4 cm fields were selected as the intermediate fields with the maximum deviation of 0. 29%. Conclusions For the detectors with changing response along with the field size,daisy-chaining measurement method can be utilized to extend the measurement range and improve the accuracy of the measurement results.%目的 针对响应随射野面积变化的探测器,应用基于菊花链( Daisy-Chaining)的射野输出因子测量方法,提高测量结果的准确性.方法 分别使用IBA CC13电离室、IBA CC01电离室、IBA Razor半导体探测器、IBA EFD半导体探测器和Gafchromic EBT3胶片测量Varian Edge加速器6 MV X线的射野输出因子.结果 同Razor和CC13衔接的菊花链测量结果相比,常规测量方法使用CC13测量小野时结果偏小,在射野1 cm×1 cm时偏差达到16. 71%.使用CC01测量大野时结果偏大,在射野40 cm×40 cm时偏差达到8. 39%.使用Razor测量大野时结果偏大,在射野40 cm×40 cm时偏差达到9. 40%. EFD的测量结果与Razor结果接近,在射野40 cm×40 cm时偏差为9. 14%.使用胶片测量1 cm×1 cm以上的射野时,与菊花链测量结果接近,偏差在1. 60%以内,在射野1 cm×1 cm时偏差则达到3. 13%.选择射野3 cm×3 cm或4 cm×4 cm作为中间野的菊花链测量结果一致,最大偏差0. 29%.结论 对于响应随射野面积变化的探测器可通过菊花链的方法来扩大测量范围,提高测量结果的准确性.