Resumo

MACHADO, Norman H  e  RESTREPO, Johans. _{^{kfclin,fmsrQclin,Qmrs}} CORRECTION FACTORS OF PLASTIC SCINTILLATORS AND OTHER STEREOTACTIC DETECTORS FOR SUB-CENTIMETER PHOTON FIELDS USING MONTE CARLO. Momento [online]. 2017, n.55, pp.1-25. ISSN 0121-4470.  https://doi.org/10.15446/mo.n55.66140.

The goals of this work are: (1) To evaluate a plastic scintillation detector and other stereotactic dosimeters for measuring output factors, dose profiles and percent depth dose curves of small and sub-centimeter radiation fields and (2) to obtain tables ofcorrection factors based on Monte Carlo simulations using codes BEAMnrc and DOSXYZnrc.

Tables of output ratios and dose profiles for radiation fields conformed by a micro-multileaf collimator were obtained for the stereotactic detectors: 1) Standard Imaging W1 Exradin Plastic Scintillation Detector with 1 mm diameter and 3 mm length, 2) PTW dosimetry diode E type 60017 with 1.13 mm diameter and 30 μm thickness and 3) PTW Pinpoint 31016 3D ionization chamber with 3.13 mm diameter.

Monte Carlo BEAMnrc simulations were performed for the 6 MeV energy of a Varian Clinac iX linear accelerator with the micro-multileaf collimator attached to its gantry. The DOSXYZnrc Monte Carlo code was used to calculate the output factorsand the dose profiles in a virtual water phantom by means of the phase space file obtained from the BEAMnrc simulation. Thefactor tables presented in this work show that for field sizes with radius larger than the range of secondary charged particles, the corrections for the set of detectors are lower than 7 % compared with Monte Carlo calculations. However, for sub-centimeter radiation fields, the corrections are about of 23 % for the PTW Pinpoint ionization chamber and up to 12 % for the rest of detectors.

Palavras-chave : Small field dosimetry; Monte Carlo BEAMnrc & DOSXYZnrc; field output factors; plastic scintillation detectors; stereotactic detectors.

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