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Evaluation of Patient-Specific Quality Assurance Based On Different Methods

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S Xu

T Yang , B Qu , X Dai , C Xie , W Xiaoshen , X Cong , J Wang , S Xu*, PLA General Hospital, Beijing, BJ


SU-I-GPD-T-296 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To evaluate the availability of patient-specific quality assurance (QA) using different methods.

Methods: 12 VMAT treatment plans delivered by Clinac iX machine (Varian, US) with EPID were selected. The absolute dose, pre-treatment and in-vivo dose verification were implemented with software and hardware tools, respectively. And the quantitative evaluation would be analyzed. The software tools include Mobuis3D (Mobius Medical Systems, US), EPIgray/ EPIbeam (DOSIsoft, France), SNC/3DVH (SunNuclear, US) and Eclipse treatment planning system (TPS, Ver10.1) for dose reconstruction, and the hardware tools are A1SL chamber, cheese phantom, ArcCheck (SunNuclear, US) and EPID for measurement. Of course, the log files of delivered plan were obtained and used for dose verification.

Results: The point dose in the middle of cheese phantom from EPIgray, Mobuis and chamber showed a little difference of 1.78±1.22)%, 2.38±0.88% and 2.96±0.86%. A good consistency was seen for the gamma passing rates of 2D (EPIbeam: 98.20±2.16% vs SNC: 98.15±1.73%) and 3D (3DVH: 99.16±1.81)% vs Mobius: 98.12±1.36%) pre-treatment verification. In addition, the mean dose difference between the predicted and reconstructed dose with EPIgray was (-1.47±1.48)% in in-vivo dose verification, and the mean 3D gamma passing rate with Mobius was (96.66±2.60)% using the delivered log files.

Conclusion: The patient-specific QA using different methods, which are software or hardware tools, pre-treatment or in-vivo verification, have been available during radiotherapy, and they may be a kind of complementary relationship. Until now, the accuracy and quality of these software methods largely depend on their functions, algorithms and software maturity.

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