ESTRO 2022 - Abstract Book

S785

Abstract book

ESTRO 2022

Conclusion Although a predictive model for TomoTherapy ® patient-specific QA is yet to come, the introduction of the newly developed complexity metrics and sinograms’ radiomics features reduces the gap towards its definition.

References [1] https://github.com/SamueleCavinato/TCoMX [2] Santos, T. et al . (2020), doi.org/10.1002/acm2.12895 [3] Cavinato, S. et al. (2021) to be submitted [4] Bettinelli, A. et al . (2019), doi.org/10.1002/mp.13956 [5] Miften, M. et al . (2018), doi.org/10.1002/mp.12810

PD-0893 Enhancing patient safety with log file analysis : perFRACTION® optimal gamma criteria for VMAT QA

F. itta 1 , G.M. Mistretta 1 , P. Ceroni 1 , V. Gutierrez 1 , F. Campanaro 1 , L. Morini 1 , F. Marino 1 , S. Koubegnery 2 , E. D'Angelo 3 , G. Guidi 1 1 University Hospital of Modena, Medical Physics Unit, Modena, Italy; 2 International Centre for Theoretical Physics & University of Trieste, Master in Medical Physics Student, Trieste, Italy; 3 University Hospital of Modena, Radiotherapy Unit– Oncology and Hematology department, Modena, Italy Purpose or Objective Introducing an automatic log file based analysis tool such as perFRACTION® into clinical practice could be a time-saving strategy for on-line patient specific VMAT QA enhancing patient safety and risk management. The perFRACTION® log-file based only (LFO) strategy has been investigated as an alternative method to phantom based (Matrixx®) patient specific VMAT QA. The purpose was to evaluate the optimal gamma criterion for the perFRACTION® LFO strategy to catch clinically relevant error scenarios. Materials and Methods By manipulating three gold standard (error free) VMAT plans optimized with the Raystation® TPS, a total of 33 error plans were generated by using a home made Python scripting procedure. Different magnitudes of errors were simulated in terms of multi-leaf collimator (MLC) position (MLC shift: [+1mm,+2mm], MLC misalignment: [+0.25mm,+0.5mm,+0.75mm]), collimator angle (angle rotation: [+2°,+4°]) and monitor unit (MU) delivery (MU :[±1%, ±2%]). All the error free and the corresponding error plans were delivered with an Elekta Versa HD and QA was performed simultaneously with both the perFRACTION ® (LFO) and Matrix® (phantom-based) systems for different gamma criteria (3%/3 mm/Global Th5%, 3%/2 mm/Global Th10%, 2%/2 mm/Global Th5%, 1.5%/1.5 mm/Global Th10%, 1.5%/1.5 mm/Global Th5%, 1%/1 mm/Global Th10%). The resulting gamma passing rates were analysed. Results The impact of gamma criteria on the error detection capability for both systems investigated is shown in the scatter plots in figure 1. Each scatter plot focus on a different gamma criterion. The x position of each data point corresponds to the gamma passing rate of an error scenario obtained with Matrixx and its y position to its perFRACTION value. All data points are normalized with respect their own error free plan gamma passing rate value. As data points below the diagonal line indicate a lower gamma passing rate value for perFRACTION (better error detection capability for the system), it results