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Feasibility of a Low-Cost, In-House, and Real Time HDR Source Position Verification System

E Galhardo*, j Fang , G Narayanasamy , X Zhang , S Morrill , T Kim , University of Arkansas for Medical Sciences, Little Rock, AR


(Monday, 7/30/2018) 9:30 AM - 10:00 AM

Room: Exhibit Hall | Forum 4

Purpose: HDR daily real time source position verification using a generic webcam.

Methods: A generic webcam in conjunction with an in-house VBA (Microsoft Visual Studio 2015) program is used to implement a real time verification of the HDR source position for a daily QA test with option to capture the image and generate a report for documentation. A preliminary test with Gafchromic film was used to insure that the radiographic central core of the source matched the geometric center position (Nucletron uses this position as the nominal dwell position). A quick check with a wire of a known distance was used for consistency and system verification performance (parallax, image quality, live camera, and the quality of image captured). The programmed value and the visual position of the source center were entered manually in the form, and the pass/fail results were automatically displayed.

Results: The executable files are stored on our network, and doesn’t need Visual Studio installed on any computer. We tested the source position verification setup with our Nucletron HDR system. The good quality of image allowed us to quantify the source position displacement very easily, in terms of submillimeter, and the final results were in good agreement with the Gafchromic film (<0.5mm).

Conclusion: Our system allows extra flexibility compared to current available commercial test systems. It can be used to test any source/dummy position, the user can setup the pass/fail tolerance, is vendor independent, and it is a very useful tool for Nucletron (Elekta) or GammaMed (Varian) users that do not have vendor-supplied verification systems that can visualize, capture and record the position accuracy for the dummy and/or the HDR source. Our system can also be used for HDR service engineer to check the live dummy/source position during the source exchange process, and make the necessary adjustments.


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