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Estimating radiation doses from multidetector CT using Monte Carlo simulations: Effects of different size voxelized patient models on magnitudes of organ and effective dose.
Phys. Med. Biol. 52, 2583-2597 (2007)
The purpose of this work is to examine the effects of patient size on radiation dose from CT scans. To perform these investigations, we used Monte Carlo simulation methods with detailed models of both patients and multidetector computed tomography (MDCT) scanners. A family of three-dimensional, voxelized patient models previously developed and validated by the GSF was implemented as input files using the Monte Carlo code MCNPX. These patient models represent a range of patient sizes and ages (8 weeks to 48 years) and have all radiosensitive organs previously identified and segmented, allowing the estimation of dose to any individual organ and calculation of patient effective dose. To estimate radiation dose, every voxel in each patient model was assigned both a specific organ index number and an elemental composition and mass density. Simulated CT scans of each voxelized patient model were performed using a previously developed MDCT source model that includes scanner specific spectra, including bowtie filter, scanner geometry and helical source path. The scan simulations in this work include a whole-body scan protocol and a thoracic CT scan protocol, each performed with fixed tube current. The whole-body scan simulation yielded a predictable decrease in effective dose as a function of increasing patient weight. Results from analysis of individual organs demonstrated similar trends, but with some individual variations. A comparison with a conventional dose estimation method using the ImPACT spreadsheet yielded an effective dose of 0.14 mSv mAs(-1) for the whole-body scan. This result is lower than the simulations on the voxelized model designated 'Irene' (0.15 mSv mAs(-1)) and higher than the models 'Donna' and 'Golem' (0.12 mSv mAs(-1)). For the thoracic scan protocol, the ImPACT spreadsheet estimates an effective dose of 0.037 mSv mAs(-1), which falls between the calculated values for Irene (0.042 mSv mAs(-1)) and Donna (0.031 mSv mAs(-1)) and is higher relative to Golem (0.025 mSv mAs(-1)). This work demonstrates the ability to estimate both individual organ and effective doses from any arbitrary CT scan protocol on individual patient-based models and to provide estimates of the effect of patient size on these dose metrics.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
multidetector CT; MDCT; patient size; voxel models; organ dose; effective dose; Monte Carlo simulation
Language
english
Publication Year
2007
HGF-reported in Year
2007
ISSN (print) / ISBN
0031-9155
e-ISSN
1361-6560
Journal
Physics in Medicine and Biology
Quellenangaben
Volume: 52,
Issue: 9,
Pages: 2583-2597
Publisher
Institute of Physics Publishing (IOP)
Publishing Place
Bristol
Reviewing status
Peer reviewed
Institute(s)
Institute of Radiation Protection (ISS)
POF-Topic(s)
30504 - Mechanisms of Genetic and Environmental Influences on Health and Disease
Research field(s)
Radiation Sciences
PSP Element(s)
G-501100-008
PubMed ID
17440254
WOS ID
000246172000017
Scopus ID
34249087431
Erfassungsdatum
2007-04-17