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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Georg D, Knöös T, McClean B. Current status and future perspective of flattening filter free photon beams. Med Phys. 2011;38:1280–93.
Lang S, Shrestha B, Graydon S, Cavelaars F, Linsenmeier C, Hrbacek J, Klöck S, Studer G, Riesterer O. Clinical application of flattening filter free beams for extracranial stereotactic radiotherapy. Radiother Oncol. 2013;106:255–9.
Japan Society of Medical Physics. Standard dosimetry of absorbed dose to water in external beam radiotherapy (standard dosimetry 12). Tokyo: Tsusho-Sangyo Kenkyu-Sha; 2012.
Stasi M, Baiotto B, Barboni G, Scielzo G. The behavior of several microionization chambers in small intensity modulated radiotherapy fields. Med Phys. 2004;31:2792–5.
Agostinelli S, Garelli S, Piergentili M, Foppiano F. Response to high-energy photons of PTW31014 PinPoint ion chamber with a central aluminum electrode. Med Phys. 2008;35:3293–301.
Shimono T, Koshida K, Nambu H, Matsubara K, Takahashi H, Okuda H. Polarity effect in commercial ionization chambers used in photon beams with small fields. Radiol Phys Technol. 2009;2:97–103.
McEwen MR. Measurement of ionization chamber absorbed dose k(Q) factors in megavoltage photon beams. Med Phys. 2010;37:2179–93.
Fu W, Dai J, Hu Y, Han D, Song Y. Delivery time comparison for intensity-modulated radiation therapy with/without flattening filter: a planning study. Phys Med Biol. 2004;49:1535–47.
Scorsetti M, Alongi F, Castiglioni S, Clivio A, Fogliata A, Lobefalo F, Mancosu P, Navarria P, Palumbo V, Pellegrini C, Pentimalli S, Reggiori G, Ascolese AM, Roggio A, Arcangeli S, Tozzi A, Vanetti E, Cozzi L. Feasibility and early clinical assessment of flattening filter free (FFF) based stereotactic body radiotherapy (SBRT) treatments. Radiat Oncol. 2011;6:113.
Glide-Hurst C, Bellon M, Foster R, Altunbas C, Speiser M, Altman M, Westerly D, Wen N, Zhao B, Miften M, Chetty IJ, Solberg T. Commissioning of the Varian TrueBeam linear accelerator: a multi-institutional study. Med Phys. 2013;40:031719.
Martens C, De Wagter C, De Neve W. The value of the PinPoint ion chamber for characterization of small field segments used in intensity-modulated radiotherapy. Phys Med Biol. 2000;45:2519–30.
McEwen M, DeWerd L, Ibbott G, Followill D, Rogers DW, Seltzer S, Seuntjens J. Addendum to the AAPM’s TG-51 protocol for clinical reference dosimetry of high-energy photon beams. Med Phys. 2014;41:041501.
Ramsey CR, Spencer KM, Oliver AL. Ionization chamber, electrometer, linear accelerator, field size, and energy dependence of the polarity effect in electron dosimetry. Med Phys. 1999;26:214–9.
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This work was supported by Grant-in-Aid for Scientific Research 15K19204 by the Japan Society for the Promotion of Science.
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Ogata, T., Uehara, K., Nakayama, M. et al. Polarity correction factor for flattening filter free photon beams in several cylindrical ionization chambers. Radiol Phys Technol 9, 187–192 (2016). https://doi.org/10.1007/s12194-016-0348-3
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DOI: https://doi.org/10.1007/s12194-016-0348-3