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Beam monitor calibration in scanned light‐ion beams
Author(s) -
Palmans Hugo,
Vatnitsky Stanislav M.
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4963808
Subject(s) - ionization chamber , dosimetry , ionization , physics , calibration , beam (structure) , optics , formalism (music) , faraday cup , beam energy , atomic physics , computational physics , ion beam , ion , nuclear medicine , musical , quantum mechanics , visual arts , medicine , art
Purpose To propose a formalism for the reference dosimetry of scanned light‐ion beams consistent with IAEA TRS‐398 and Alfonso et al. [Med. Phys. 35 , 5179–5186 (2008)]. To identify machine‐specific reference ( msr ) fields and plan‐class specific reference ( pcsr ) fields consistent with the definitions given by Alfonso et al. To review the literature of beam monitor calibration in scanned beams using three different methods in terms of this common formalism. Methods Four types of msr fields are identified as those that are meant to calibrate the beam monitor for scanned beams with particular energies. Two types of pcsr fields are identified as those that are meant to apply one or more tuning factors to the entire delivery chain. Results The formalism establishes the energy‐dependent relation between the number of particles incident on the phantom surface and the beam monitor reading and distinguishes three routes to determine the beam monitor calibration function: (i) the use of a calibrated reference ionization chamber in a single‐layer scanned beam, (ii) the use of a cross‐calibrated large‐area parallel plate ionization chamber in a single‐energy beamlet, and (iii) the use of a calibrated reference ionization chamber in a box field to adjust a calibration curve obtained by a Faraday cup or an ionization chamber. Examples of all three methods and comparisons between them from the literature are analysed. Conclusions The formalism can form the basis of future dosimetry recommendations for scanned particle beams and the analysis of the literature data in terms of this formalism can form the basis of data compilations for the application of the dosimetry procedures.