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Towards Efficient Automated LINAC Quality Assurance: A Feasibility Study

S Lim , R Kuo , L Happersett , L Hong , X Li , D Lovelock*, Memorial Sloan-Kettering Cancer Center, New York, NY


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: The increased complexity and geometric accuracy of radiation delivery required for SBRT and cranial SRS has increased the number of tests and the time required for monthly Linac quality assurance (QA). This study investigates the feasibility of a QA process to automate and expedite our current QA workflow.

Methods: In our clinic, machine performance check (MPC), an image-based automatic self-test tool integrated into TrueBeams (Varian, Palo Alto, CA), is run daily by therapists using the 6 MV beam. It provides quantitative information of collimator, gantry, couch pitch, roll, and yaw angles, and positions of couch, jaws, mlc leaves, MV-kV coincidence, and isocenter size. It is hypothesized that tests that are part of our current monthly QA (CQAW) which overlap with MPC can be eliminated. Additionally, portal dosimetry (PD) (Varian, Palo Alto, CA), which compares measured EPID and calculated fluence, can be used to replace all MLC related tests currently done with film and ionization chamber (IC). Tests are run in Treatment Mode. Only output is performed using the IC in Service Mode. The average QA times () used by four physicists performing the monthly QA in both workflows were compared.

Results: The for CQAW and NQAQ were found to be 5.1 and 2.4 hours respectively translating to 53% reduction in time. 40% of the reduction was attributed to test elimination due to MPC and 9% to increased efficiency of the PD replacements. The remaining 4% was attributed to error reduction and an efficient logistic using an Aria test patient.

Conclusion: The results are based on a small sample. More samples will be acquired to determine the reproducibility of the results. Significant improvement in efficiency is achievable.

Funding Support, Disclosures, and Conflict of Interest: This work was partially supported by the MSK Cancer Center Support Grant/Core Grant (P30 CA008748)


Quality Assurance, Linear Accelerator


TH- External beam- photons: Quality Assurance - Linear accelerator

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