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Program Information

Keystroke Emulator Device for Automated Service Mode Driven QA Tests

J Bredfeldt

J Bredfeldt1*, S Hadley2 , K Lam3 , (1) Brigham and Women's Hospital, Boston, MA, (2) The University of Michigan, Ann Arbor, MI, (3) University of Michigan, Ann Arbor, MI


SU-I-GPD-T-226 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To validate a simple, low cost solution to improve automation of Varian C-series linac quality assurance (QA).

Methods: An Atmega328 microcontroller is used to emulate a PS2 keyboard such that keystrokes are programmatically sent to the console computer of a Varian C-series linac. An FT232RL integrated circuit allows a computer to interface with the Atmega328 over a virtual com port. Computer software was written to control the linac by sending serial commands to the Atmega328 which converts them to PS2 keystroke sequences and sends them to the console computer. This allows the computer software to, for example, turn on or turn off the beam. When keystrokes are not being sent by the control program, a digitally controlled switch routes the standard service mode keyboard to the console computer. The same computer software is also used to communicate with an electrometer allowing for automated ion-chamber reading and recording. We demonstrate feasibility by comparing the number of keystrokes required to perform 4 common QA tests (monthly outputs, energy checks, Scp checks, and output with gantry angle checks) with and without the device.

Results: The prototype hardware materials were purchased for $39.49, assembled and mounted in a small box. The hardware and software were demonstrated to operate as designed on a Varian C-series Linac during monthly and annual QA. The keystroke analysis demonstrated that 96% of the user’s keystrokes can be eliminated by the use of our system. The hardware design, bill of materials, source code, and a demonstration workbook are available online at https://github.com/Open-Source-Medical-Devices/LinacController.

Conclusion: A prototype linac controller and data acquisition system has been tested for improving QA efficiency by automating manual control of the linac and measurement transcription. The system is low cost, open source, and may be modified for a variety of applications.

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