Technical Note: A feasibility study of using the flat panel detector on linac for the kV x-ray generator test

Bin Cai, Steven Dolly, Gregory Kamal, Sridhar Yaddanapudi, Baozhou Sun, S. Murty Goddu, Sasa Mutic, Hua Li

Research output: Contribution to journalArticlepeer-review


Purpose: To investigate the feasibility of using kV flat panel detector on linac for consistency evaluations of kV x-ray generator performance. Methods: An in-house designed aluminum (Al) array phantom with six 9 × 9 cm2 square regions having various thickness was proposed and used in this study. Through XML script-driven image acquisition, kV images with various acquisition settings were obtained using the kV flat panel detector. Utilizing pre-established baseline curves, the consistency of x-ray tube output characteristics, including tube voltage accuracy, exposure accuracy and exposure linearity was assessed through image quality assessment metrics including ROI mean intensity, ROI standard deviation (SD), and noise power spectrums (NPS). The robustness of this method was tested on two linacs for a 3-month period. Results: With the proposed method, tube voltage accuracy can be verified through conscience check with a 2% tolerance and 2 kVp intervals for forty different kVp settings. The exposure accuracy can be tested with a 4% consistency tolerance for three mAs settings over forty kVp settings. The exposure linearity tested with 3 mAs settings achieved a coefficient of variation (CV) of 0.1. Conclusion: We proposed a novel approach that uses the kV flat panel detector available on linac for x-ray generator test. This approach eliminates the inefficiencies and variability associated with using third-party QA detectors while enabling an automated process.

Original languageEnglish
Pages (from-to)3305-3314
Number of pages10
JournalMedical physics
Issue number7
StatePublished - Jul 2018


  • on-board imager
  • quality assurance
  • x-ray generator


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