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Irradiator Commissioning and Dosimetry for Assessment of LQ α and β Parameters, Radiation Dosing Schema, and in vivo Dose Deposition
Published on: March 11, 2021
Polarity correction factor for flattening filter free photon beams in several cylindrical ionization chambers
Toshiyuki Ogata1, Kazuyuki Uehara2, Masao Nakayama2
1Division of Medical Technology Support, Kobe Minimally Invasive Cancer Center, 8-5-1, Minatojima-nakamachi, Chuo-ku, Kobe, 650-0046, Japan. ogata@k-mcc.net.
Abstract:
In this study, we aimed to compare the polarity correction factor in ionization chambers for flattening filter free (FFF) photon beams and flattening filter (FF) beams. Measurements were performed with both 6 and 10 MV FFF and FF beams. Five commercial ionization chambers were evaluated: PTW TN30013; IBA Dosimetry CC01, CC04, and CC13; and Exradin A12S. Except for the CC01 ionization chamber, the other four chambers showed less than a 0.3 % difference in the polarity effect between the FFF and the FF beams. The CC01 chamber showed a strong field-size-dependence, unlike the other chambers. The polarity effect for all chambers with FFF beams did not change with the dose rate. Except in the case of the CC01 chamber, the difference in the polarity effect between FFF and FF beams was not significant.
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