Evaluation of an organ-based tube current modulation tool in pediatric CT examinations
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COMPUTED TOMOGRAPHY
Evaluation of an organ-based tube current modulation tool in pediatric CT examinations Antonios E. Papadakis 1 & John Damilakis 2 Received: 22 November 2019 / Revised: 16 March 2020 / Accepted: 10 April 2020 # The Author(s) 2020
Abstract Objectives To investigate the effect of an organ-based tube current modulation (OTCM) technique on organ absorbed dose and assess image quality in pediatric CT examinations. Methods Four physical anthropomorphic phantoms that represent the average individual as neonate, 1-year-old, 5-year-old, and 10-year-old were used. Standard head and thorax acquisitions were performed with automatic tube current modulation (ATCM) and ATCM+OTCM. Dose calculations were performed by means of Monte Carlo simulations. Radiation dose was measured for superficial and centrally located radiosensitive organs. The angular range of the OTCM exposure window was determined for different tube rotation times (t) by means of a solid-state detector. Image noise was measured as the standard deviation of the Hounsfield unit value in regions of interest drawn at selected anatomical sites. Results ATCM+OTCM resulted in a reduction of radiation dose to all radiosensitive organs. In head, eye lens dose was reduced by up to 13% in ATCM+OTCM compared with ATCM. In thorax, the corresponding reduction for breast dose was up to 10%. The angular range of the OTCM exposure window decreased with t. For t = 0.4 s, the angular range was limited to 74° in head and 135° for thorax. Image noise was significantly increased in ATCM+OTCM acquisitions across most examined phantoms (p < 0.05). Conclusions OTCM reduces radiation dose to exposed radiosensitive organs with the eye lens and breast buds exhibiting the highest dose reduction. The OTCM exposure window is narrowed at short t. An increase in noise is inevitable in images located within the OTCM-activated imaged volume. Key Points • In pediatric CT, organ-based tube current modulation reduces radiation dose to all major primarily exposed radiosensitive organs. • Image noise increases within the organ-based tube current modulation enabled imaged volume. • The angular range of the organ-based tube current modulation low exposure window is reduced with tube rotation time. Keywords Tomography, x-ray computed . Child . Radiation dosage . Monte Carlo method . Radiation protection
Abbreviations ASIR Adaptive statistical iterative reconstruction ATCM Automatic tube current modulation CTDIvol Volume computed tomography dose index DICOM Digital Imaging and Communications in Medicine MC Monte Carlo
OTCM PMMA ROI t
Organ-based tube current modulation Polymethyl methacrylate Region of interest Tube rotation time
Introduction * Antonios E. Papadakis [email protected] 1
Department of Medical Physics, University Hospital of Heraklion, Stavrakia, 71110 Heraklion, Crete, Greece
2
Department of Medical Physics, University of Crete, Medical School, Stavrakia, 71110 Heraklion, Crete, Greece
The lens of the eye and breast are considered among the most radiosensitive tis
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