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The Effects of Arm Speed for Quality Assurance and Commissioning Measurements in Rectangular and Cylindrical Scanners

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M Bakhtiari

M Bakhtiari*, J Schmitt , RadAmerica, LLC--MedStar Health, Baltimore, MD


SU-E-T-598 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: Cylindrical and rectangular scanning water tanks are examined with different scanning speeds to investigate the TG-106 criteria and the errors induced in the measurements.

Methods: Beam profiles were measured in a depth of R50 for a low-energy electron beam (6 MeV) using rectangular and cylindrical tanks. The speeds of the measurements (arm movement) were varied in different profile measurements. Each profile was measured with a certain speed to obtain the average and standard deviation as a parameter for investigating the reproducibility and errors.

Results: At arm speeds of ~0.8 mm/s the errors were as large as 2% and 1% with rectangular and cylindrical tanks, respectively. The errors for electron beams and for photon beams in other depths were within the TG-106 criteria of 1% for both tank shapes.

Conclusion: The measurements of low-energy electron beams in a depth of R50, as an extreme case scenario, are sensitive to the speed of the measurement arms for both rectangular and cylindrical tanks. The measurements in other depths, for electron beams and photon beams, with arm speeds of less than 1 cm/s are within the TG-106 criteria. An arm speed of 5 mm/s appeared to be optimal for fast and accurate measurements for both cylindrical and rectangular tanks.

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