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目的:通过电子射野影像装置(Electronic Portal Imaging Device,EPID)平面处测量得到的透射剂量分布重建到模体表面前的原射线注量分布。方法:使用SUN NUCLEAR公司的二维半导体阵列(Mapcheck2)和PTW公司的OCTAVIUS Detector 1000SRS测量有模体和无模体时不同大小射野在EPID平面处的透射剂量,通过笔者编写的算法重建入射原射线注量分布,并与三维水箱探头加带平衡帽测量的原射线注量分布比较。结果:采用Gamma法(3 mm/3%)进行评估,在射野内Mapcheck2和OCTAVIUS Detector 1000SRS探测器通过率为100%。结论:本次研究建立的模型得出的原射线离轴比的准确性可满足临床要求,可以用于剂量验证。
OBJECTIVE: To reconstruct the original fluence distribution in front of the mold surface by using the transmitted dose distribution measured at the plane of Electronic Portal Imaging Device (EPID). Methods: Using SUN NUCLEAR’s two-dimensional semiconductor array (Mapcheck2) and PTW’s OCTAVIUS Detector 1000SRS measurement of phantom and no-mold body when the size of the different fields in the EPID plane transmitted dose, by the author’s algorithm to reconstruct the incident Ray flux distribution, and with the three-dimensional water tank probe with a balanced cap measurements of the original ray fluency distribution comparison. Results: The Gamma method (3 mm / 3%) was used to assess the pass-through rate of Mapcheck2 and OCTAVIUS Detector 1000SRS detectors in the field of 100%. Conclusion: The accuracy of the off-axis ratio of the original radiations obtained from the model established in this study can meet the clinical requirements and can be used for dose verification.