Lourenco, A;
Wellock, N;
Thomas, R;
Homer, M;
Bouchard, H;
Kanai, T;
MacDougall, N;
... Palmans, H; + view all
(2016)
Theoretical and experimental characterization of novel water-equivalent plastics in clinical high-energy carbon-ion beams.
Physics in Medicine and Biology
, 61
(21)
pp. 7623-7638.
10.1088/0031-9155/61/21/7623.
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Ferreira De Almeida Lourenco_Lourenço_2016_Phys._Med._Biol._61_7623.pdf - Published Version Download (0B) |
Abstract
Water-equivalent plastics are frequently used in dosimetry for experimental simplicity. This work evaluates the water-equivalence of novel water-equivalent plastics specifically designed for light-ion beams, as well as commercially available plastics in a clinical high-energy carbon-ion beam. A plasticto- water conversion factor Hpl,w was established to derive absorbed dose to water in a water phantom from ionization chamber readings performed in a plastic phantom. Three trial plastic materials with varying atomic compositions were produced and experimentally characterized in a high-energy carbon-ion beam. Measurements were performed with a Roos ionization chamber, using a broad un-modulated beam of 11 × 11 cm2, to measure the plastic-to-water conversion factor for the novel materials. The experimental results were compared with Monte Carlo simulations. Commercially available plastics were also simulated for comparison with the plastics tested experimentally, with particular attention to the influence of nuclear interaction cross sections. The measured Hpl,w exp correction increased gradually from 0% at the surface to 0.7% at a depth near the Bragg peak for one of the plastics prepared in this work, while for the other two plastics a maximum correction of 0.8%– 1.3% was found. Average differences between experimental and numerical simulations were 0.2%. Monte Carlo results showed that for polyethylene, polystyrene, Rando phantom soft tissue and A-150, the correction increased from 0% to 2.5%–4.0% with depth, while for PMMA it increased to 2%. Water-equivalent plastics such as, Plastic Water, RMI-457, Gammex 457-CTG, WT1 and Virtual Water, gave similar results where maximum corrections were of the order of 2%. Considering the results from Monte Carlo simulations, one of the novel plastics was found to be superior in comparison with the plastic materials currently used in dosimetry, demonstrating that it is feasible to tailor plastic materials to be water-equivalent for carbon ions specifically.
| Type: | Article |
|---|---|
| Title: | Theoretical and experimental characterization of novel water-equivalent plastics in clinical high-energy carbon-ion beams |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1088/0031-9155/61/21/7623 |
| Publisher version: | http://dx.doi.org/10.1088/0031-9155/61/21/7623 |
| Language: | English |
| Additional information: | © 2016 Institute of Physics and Engineering in Medicine. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. |
| Keywords: | Science & Technology, Technology, Life Sciences & Biomedicine, Engineering, Biomedical, Radiology, Nuclear Medicine & Medical Imaging, Engineering, Carbon-Ion Radiotherapy, Water-Equivalent Plastics, Relative Dosimetry, Conversion Factors, Fluence Correction Factors, Stopping-Power Ratios, Proton-Beams, Monte-Carlo, Graphite Calorimetry, Particle Therapy, Phantom Material, Dosimetry, Radiotherapy, Distributions |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1524774 |
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