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Novel Amorphous Silicon Detector Array for Linear Accelerator Electron Measurements

M Shaikh1*, J Burmeister2 , (1) Rochester General Hospital, Rochester, NY, (2) Wayne State university School of Medicine, Detroit, MI


(Sunday, 7/29/2018) 3:00 PM - 6:00 PM

Room: Exhibit Hall

Purpose: To validate and benchmark the QA StereoChecker (QASC), a novel high resolution (aSi) dosimeter, for clinical electron measurements using an ion chamber and gafchromic film.

Methods: The Standard Imaging proprietary software was used to characterize reproducibility of the detector for open field electron beams between 6 and 20 MeV at varying dose rates. The short term reproducibility of the detector was evaluated by making measurements over an 8 hour day, while the long term reproducibility characterizes detector response over two weeks; with an ion chamber being used to adjust for machine output variations. A subset of cone and cut out factors were cross-compared with an ion chamber for standard cone sizes of : 6, 10 and 15 cm. Additionally, we cross compared the electron profiles with Gafchromic film to evaluate field size measurements.

Results: For all electron energies, the detector readings demonstrated excellent short term reproducibility and dose rate independence, with the standard deviation less than 0.5%. Over a span of two weeks, the maximum discrepancy between the ion chamber and QASC calibrated reading was 0.75%. The maximum difference between QASC measured cone and cut out factors compared with an ion chamber is under 1%. Additionally, the inherent high resolution of 0.2 mm, allowed the QASC field size measurement to be consistent with film measurements.

Conclusion: The QASC was shown to be a stable platform for clinical electron measurements. It offers high resolution and comparable stability to an ion chamber for quality assurance measurements.


Not Applicable / None Entered.


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

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