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Author Papadakis, Antonios E. ♦ Perisinakis, Kostas ♦ Damilakis, John
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword APPLIED LIFE SCIENCES ♦ RADIATION PROTECTION AND DOSIMETRY ♦ ABDOMEN ♦ CHEST ♦ COMPUTER CODES ♦ COMPUTERIZED TOMOGRAPHY ♦ DOSIMETRY ♦ EYES ♦ IMAGES ♦ KIDNEYS ♦ MONTE CARLO METHOD ♦ PATIENTS ♦ PEDIATRICS ♦ PELVIS ♦ PHANTOMS ♦ RADIATION DOSES ♦ REGRESSION ANALYSIS ♦ SIMULATION ♦ THYMUS
Abstract Purpose: To develop a method for estimating doses to primarily exposed organs in pediatric CT by taking into account patient size and automatic tube current modulation (ATCM). Methods: A Monte Carlo CT dosimetry software package, which creates patient-specific voxelized phantoms, accurately simulates CT exposures, and generates dose images depicting the energy imparted on the exposed volume, was used. Routine head, thorax, and abdomen/pelvis CT examinations in 92 pediatric patients, ranging from 1-month to 14-yr-old (49 boys and 43 girls), were simulated on a 64-slice CT scanner. Two sets of simulations were performed in each patient using (i) a fixed tube current (FTC) value over the entire examination length and (ii) the ATCM profile extracted from the DICOM header of the reconstructed images. Normalized to CTDI{sub vol} organ dose was derived for all primary irradiated radiosensitive organs. Normalized dose data were correlated to patient’s water equivalent diameter using log-transformed linear regression analysis. Results: The maximum percent difference in normalized organ dose between FTC and ATCM acquisitions was 10% for eyes in head, 26% for thymus in thorax, and 76% for kidneys in abdomen/pelvis. In most of the organs, the correlation between dose and water equivalent diameter was significantly improved in ATCM compared to FTC acquisitions (P < 0.001). Conclusions: The proposed method employs size specific CTDI{sub vol}-normalized organ dose coefficients for ATCM-activated and FTC acquisitions in pediatric CT. These coefficients are substantially different between ATCM and FTC modes of operation and enable a more accurate assessment of patient-specific organ dose in the clinical setting.
ISSN 00942405
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-05-15
Publisher Place United States
Journal Medical Physics
Volume Number 43
Issue Number 5


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