| Radio frequency noise from an MLC: a feasibility study of the use of an MLC for linac-MR systems. | |
| | |
MedLine Citation:
|
PMID: 20090187 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
Currently several groups are actively researching the integration of a megavoltage teletherapy unit with magnetic resonance (MR) imaging for real-time image-guided radiotherapy. The use of a multileaf collimator (MLC) for intensity-modulated radiotherapy for linac-MR units must be investigated. The MLC itself will likely reside in the fringe field of the MR and the motors will produce radio frequency (RF) noise. The RF noise power spectral density from a Varian 52-leaf MLC motor, a Varian Millennium MLC motor and a brushless fan motor has been measured as a function of the applied magnetic field using a near field probe set. For the Varian 52-leaf MLC system, the RF noise produced by 13 of 52 motors is studied as a function of distance from the MLC. Data are reported in the frequency range suitable for 0.2-1.5 T linac-MR systems. Below 40 MHz the Millennium MLC motor tested showed more noise than the Varian 52-leaf motor or the brushless fan motor. The brushless motor showed a small dependence on the applied magnetic field. Images of a phantom were taken by the prototype linac-MR system with the MLC placed in close proximity to the magnet. Several orientations of the MLC in both shielded and non-shielded configurations were studied. For the case of a non-shielded MLC and associated cables, the signal-to-noise ratio (SNR) was reduced when 13 of 52 MLC leaves were moved during imaging. When the MLC and associated cables were shielded, the measured SNR of the images with 13 MLC leaves moving was experimentally the same as the SNR of the stationary MLC image. When the MLC and cables are shielded, subtraction images acquired with and without MLC motion contains no systematic signal. This study illustrates that the small RF noise produced by functioning MLC motors can be effectively shielded to avoid SNR degradation. A functioning MLC can be incorporated into a linac-MR unit. |
| | |
Authors:
|
M Lamey; J Yun; B Burke; S Rathee; B G Fallone |
Related Documents
:
|
17503917 - Wire tomography in the h-1nf heliac for investigation of fine structure of magnetic isl... 15556657 - Present and future magnetic resonance sources of exposure to static fields. 18040337 - Generation of achromatic and propagation-invariant spot arrays by use of continuously s... 3700437 - Porosity-geometry interaction in the conservation of bone strength. 7942997 - Is fragile x syndrome a pervasive developmental disability? cognitive ability and adapt... 3911747 - Ct stereotactic biopsy for optimizing the therapy of intracranial processes. |
Publication Detail:
|
Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-01-20 |
Journal Detail:
|
Title: Physics in medicine and biology Volume: 55 ISSN: 1361-6560 ISO Abbreviation: Phys Med Biol Publication Date: 2010 Feb |
Date Detail:
|
Created Date: 2010-02-03 Completed Date: 2010-04-23 Revised Date: 2010-09-27 |
Medline Journal Info:
|
Nlm Unique ID: 0401220 Medline TA: Phys Med Biol Country: England |
Other Details:
|
Languages: eng Pagination: 981-94 Citation Subset: IM |
Affiliation:
|
Department of Physics, University of Alberta, Alberta, T6G 2G7, Canada. mlamey@phys.ualberta.ca |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Algorithms Artifacts* Electromagnetic Fields Feasibility Studies Magnetic Resonance Imaging / instrumentation*, methods Phantoms, Imaging Radio Waves* Radiotherapy, Intensity-Modulated / instrumentation, methods |
| Grant Support | |
ID/Acronym/Agency:
|
93752//Canadian Institutes of Health Research |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Cardiac biplane strain imaging: initial in vivo experience.
Next Document: Numerical study of RF exposure and the resulting temperature rise in the foetus during a magnetic re...