Document Detail


CT dosimetry considerations in non typical conditions: The effect of scan field of view and table height selection.
MedLine Citation:
PMID:  21454113     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
PURPOSE: To experimentally investigate the effect of the scan field of view (SFOV) selection and table height settings on the Computed Tomography Dose Index (CTDI) and the implications concerning patient effective and skin dose. METHODS: Air-kerma length product (AKLP) measurements were carried out in a helical CT scanner using a pencil type dosimeter positioned in air and inside the holes of a head and a body phantom, using all available SFOV selections and different table height settings. Furthermore, using radiotherapy verification films placed on the CT table surface, the entrance surface air kerma (ESAK) profiles were derived with different SFOV and table height selections, both with and without a phantom on top of the films. RESULTS: The AKLP is strongly dependent on the SFOV selection and the table height settings. Different SFOV selections correspond to the selection of different bowtie filters that shape the X-ray beam intensity, resulting in different ESAK values at the isocenter and at the other points within the scanning plane. With the off-center positioning the calculated CTDI values within the center and the periphery of the phantom change also, as a result of the different intensity and width of the X-ray beam to which are exposed to. CONCLUSIONS: The existing protocols for calculating effective dose are limited to only two patient anatomy-SFOV combinations and cannot account for off-center positioning. Therefore, more work will be required to estimate the effective and skin dose for non-standard SFOV-patient anatomy combinations and off-center patient positioning.
Authors:
Ioannis A Tsalafoutas; Paraskevi Georgolopoulou; Ioannis Abatzoglou
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-3-29
Journal Detail:
Title:  Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB)     Volume:  -     ISSN:  1724-191X     ISO Abbreviation:  -     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-4-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9302888     Medline TA:  Phys Med     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011. Published by Elsevier Ltd.
Affiliation:
Medical Physics Department, Agios Savvas Hospital, 171 Alexandras Avenue, 115 22 Athens, Greece.
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