Ion recombination correction factor in scanned light-ion beams for absolute dose measurement using plane-parallel ionisation chambers

Physics in Medicine and Biology
S RossommeH Palmans

Abstract

Based on international reference dosimetry protocols for light-ion beams, a correction factor (k s) has to be applied to the response of a plane-parallel ionisation chamber, to account for recombination of negative and positive charges in its air cavity before these charges can be collected on the electrodes. In this work, k s for IBA PPC40 Roos-type chambers is investigated in four scanned light-ion beams (proton, helium, carbon and oxygen). To take into account the high dose-rates used with scanned beams and LET-values, experimental results are compared to a model combining two theories. One theory, developed by Jaffé, describes the variation of k s with the ionization density within the ion track (initial recombination) and the other theory, developed by Boag, describes the variation of k s with the dose rate (volume recombination). Excellent agreement is found between experimental and theoretical k s-values. All results confirm that k s cannot be neglected. The solution to minimise k s is to use the ionisation chamber at high voltage. However, one must be aware that charge multiplication may complicate the interpretation of the measurement. For the chamber tested, it was found that a voltage of 300 V can be used without fur...Continue Reading

References

Sep 2, 1998·Physics in Medicine and Biology·D T Burns, M R McEwen
Sep 2, 1998·Physics in Medicine and Biology·M Boutillon
Dec 30, 1998·Physics in Medicine and Biology·T KanaiY Futami
Oct 1, 1950·The British Journal of Radiology·J W BOAG
Feb 10, 2006·Physics in Medicine and Biology·Hugo PalmansAndrzej Kacperek
Jun 17, 2008·Physics in Medicine and Biology·Stefan LorinBengt Glimelius
Apr 5, 2015·Physica Medica : PM : an International Journal Devoted to the Applications of Physics to Medicine and Biology : Official Journal of the Italian Association of Biomedical Physics (AIFB)·Sandro Rossi
Jul 3, 2016·Medical Physics·S RossommeH Palmans

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Citations

Nov 14, 2018·Medical Physics·Simona Giordanengo, Hugo Palmans
Nov 30, 2019·The British Journal of Radiology·Gloria Vilches-FreixasGeert Bosmans
Aug 1, 2019·Physics in Medicine and Biology·S RossommeH Palmans
Feb 2, 2021·Frontiers in Oncology·Jérôme DoyenPierre-Yves Bondiau
Aug 5, 2020·Zeitschrift für medizinische Physik·Jhonnatan OsorioHugo Palmans

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