Initial experiments with gel-water: towards MRI-linac dosimetry and imaging
In: urn:ISSN:0158-9938 ; urn:ISSN:1879-5447 ; Australasian Physical and Engineering Sciences in Medicine, 39, 2016
Online
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Zugriff:
Tracking the position of a moving radiation detector in time and space during data acquisition can replicate 4D image-guided radiotherapy (4DIGRT). Magnetic resonance imaging (MRI)-linacs need MRI-visible detectors to achieve this, however, imaging solid phantoms is an issue. Hence, gel-water, a material that provides signal for MRI-visibility, and which will in future work, replace solid water for an MRI-linac 4DIGRT quality assurance tool, is discussed. MR and CT images of gel-water were acquired for visualisation and electron density verification. Characterisation of gel-water at 0 T was compared to Gammex-RMI solid water, using MagicPlate-512 (M512) and RMI Attix chamber; this included percentage depth dose, tissue-phantom ratio (TPR20/10), tissue-maximum ratio (TMR), profiles, output factors, and a gamma analysis to investigate field penumbral differences. MR images of a non-powered detector in gel-water demonstrated detector visualisation. The CT-determined gel-water electron density agreed with the calculated value of 1.01. Gel-water depth dose data demonstrated a maximum deviation of 0.7% from solid water for M512 and 2.4% for the Attix chamber, and by 2.1% for TPR20/10 and 1.0% for TMR. FWHM and output factor differences between materials were ≤0.3 and ≤1.4%. M512 data passed gamma analysis with 100% within 2%, 2 mm tolerance for multileaf collimator defined fields. Gel-water was shown to be tissue-equivalent for dosimetry and a feasible option to replace solid water.
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Initial experiments with gel-water: towards MRI-linac dosimetry and imaging
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Autor/in / Beteiligte Person: | Alnaghy, SJ ; Gargett, M ; Liney, G ; Petasecca, M ; Begg, J ; Espinoza, A ; Newall, MK ; Duncan, M ; Holloway, L ; Lerch, MLF ; Lazea, M ; Rosenfeld, AB ; Metcalfe, P |
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Zeitschrift: | urn:ISSN:0158-9938 ; urn:ISSN:1879-5447 ; Australasian Physical and Engineering Sciences in Medicine, 39, 2016 |
Veröffentlichung: | Springer Nature, 2016 |
Medientyp: | academicJournal |
DOI: | 10.1007/s13246-016-0495-1 |
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