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Monte Carlo-Based Patient Specific QA Procedure for Proteus One at UFHPTI

C Liu1,2, Z Li2, Y Song1,3, M Ho2, W Hsi2, J Park2, X Liang2, H Feng3*, (1) School of Physical Sciences, University of Science and Technology of China, Hefei,AH,CN, (2) Department of Radiation Oncology, University of Florida College of Medicine, Jacksonville, FL, USA, (3) Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei,AH,CN


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: IBA (Ion Beam Applications) single room compact proton therapy system (Proteus ONE) was installed and began patient treatments on December 10, 2019. The objective of this project is to develop patient specific QA (Quality Assurance) tool for Proteus ONE based on Monte Carlo software package TOPAS.

Methods: was first commissioned for Proteus-One using measured beam data in 33 energies and system-specific geometry parameters. An AutoMCQA software was developed to extract DICOM treatment plans from RayStation TPS to TOPAS input files and to convert TOPAS output to IBA myQA opg files. AutoMCQA future calculates gamma analysis results for storage in an in-house database.

Results: TOPAS beam model was able to calculate proton ranges to within 0.1 mm, and spot sizes to within 2% compared to measured values. Validation of the TOPAS model included gamma analysis of TOPAS-calculated vs. measured planar doses for treatment plans with cubic targets (3x3x3, 5x5x5, 7x7x7 cm3 and Isocenter at 5, 15, 25 cm depth, respectively) in water phantom. Excellent Gamma agreement rates (100% for 3mm/3%, and above 95% for 2mm/2%) for all measurement planes at the proximal, mid, and distal plane depths of these cubic targets. Gamma passing rates of TOPAS calculated doses for three patient plans, including head and neck, prostate and breast cancer, at depths selected for patient plan QA measurements, are above 98.6% (3mm /%3) and 92.5% (2mm/%2).

Conclusion: highly accurate TOPAS model has been established and validated. The AutoMCQA software developed to support commissioning of TOPAS greatly facilitated the validation process of our TOPAS beam model. Considering the calculation time in TOPAS is relatively long (hours), additional work is planned to reduce the currently excessive long calculation time of TOPAS, for example application of variance reduction techniques.

Funding Support, Disclosures, and Conflict of Interest: The support provided by China Scholarship Council (CSC) during a visit of Chunbo Liu to UFHPTI is acknowledged


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